What SPL (dBz/flat) do you start to feel the subs?
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Topic: What SPL (dBz/flat) do you start to feel the subs?
Posted By: KaphaSound
Subject: What SPL (dBz/flat) do you start to feel the subs?
Date Posted: 14 April 2021 at 8:47pm
Crossposting from the soundsystem subreddit. I can't seem to find a good answer to this even though there are a couple threads on the topic. Assuming all things are equal (outside, no reflections etc..) what SPL do you start to really physically FEEL say around 30-80hz? I'm looking for flat/dBz measurements because any weighting seriously obscures the comparison of measurements at frequencies this low. At the Village at Shambhala pictured here the techs said they were measuring 130dBc at full tilt which I'm assuming is closer to 135-140dBz and this was at the console just beyond the edge of the photo not even front row.
Having experienced this I know that I don't need to compete with the giant 218 g-sub stack as it's about as physical as you'd really ever want it to be, but I do intend on throwing events where the focal point is still the physicality of the music (drumnbass, dub, dubstep, space bass etc...). Looking at the hornresp charts for the horn subs I'm planning I should be able to provide at least 130db continuous from about 33hz-80hz (+/- 3db) confidently, but all I really want to know is what's the threshold for a truly physical experience? Ideally I'm just looking for people's thoughts on a number here again in dBz as the other threads never really answered the question, and I’m guessing someone has taken measurements for this kind of thing?
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Replies:
Posted By: Tinnitus Rex
Date Posted: 14 April 2021 at 9:24pm
Volume vs Dynamics ..... Peoples ears are the only true measurement apparatus , the built in human compressor limiter everyone has will yeald different results .SPL vs Time is most important in not destroying the human apparatus.
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Posted By: Conanski
Date Posted: 14 April 2021 at 10:30pm
With a sufficient number of boxes subbass dynamics can be felt long before the average measured SPL gets very high, so an SPL number may be the wrong thing to be focusing on.
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Posted By: KaphaSound
Date Posted: 14 April 2021 at 10:50pm
Tinnitus Rex I believe there are sensory cells (parcinian corpuscles to be exact) in our skin that enable us to feel low frequencies (likely evolved due to predators/natural disasters etc) so the whole human body really encompasses the full sense of hearing. And with bass we’re talking pure sustained sine waves so continuous at 130dBc/135-140dBz on the rig above.
Conanski I want to agree with this but I can’t seem to find any solid physics behind why that would be the case. There have been interesting discussions on particle velocity in the near vs far field but ultimately I can’t imagine that it doesn’t come back down to SPL.
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Posted By: Conanski
Date Posted: 14 April 2021 at 11:33pm
I'm sure we could put SPL measurements on it, but as you are aware that tactile feel doesn't seem to coorelate well with those measurements and that is in no small part because those measurements are essentially ignoring the dynamics. Take car audio for example, a single 12 or 15" sub in the boot can produce bass you can feel at SPLs still low enough to talk over, so it's more to do with effective coupling of driver/s to airspace IMO. The same thing happens in home audio but it takes more and bigger drivers because the air volume is larger, a typical home theater sound system with say 5" sats and a single 8-10" sub just doesn't produce much of that tactile bass regardless how loud it is played, but a pair of monkey coffins with 15" woofers makes things on the coffee table dance despite the fact that they don't go as low as the dedicated sub.
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Posted By: Tinnitus Rex
Date Posted: 14 April 2021 at 11:50pm
Humans can only perceive the difference per second of an audio event, the attack of a bass note defines its apparent volume (like the G -force in an accelrating car) therefore the apparant volume is the differrence relative to silence. Thats what makes it exciting, continuous SPL is "dissatisfying" and fatiguing . There is also the Masking problem where having too mush sub means you can no longer get any deffinition in the whole sound spectrum as the air is too busy...... afterall air is the canvas that your painting in..depending on how the recorded music has had the dynamics pre mixed and limited, it is often not ideal to just scale up that sound to hi SPL unless it was mixed at that level with dynamics in mind, Some recordings try to sound loud when played quietly.. This sounds terrible when you actually play it loud. It can get like turning the contrast and colour full up on your TV. .........also check out the definition of Leq, it is very important.
------------- "couldn't we just like... use headphones?"
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Posted By: fatfreddiescat
Date Posted: 15 April 2021 at 12:16am
https://www.ted.com/talks/evelyn_glennie_how_to_truly_listen/up-next#t-2786" rel="nofollow - https://www.ted.com/talks/evelyn_glennie_how_to_truly_listen/up-next#t-2786
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Posted By: Conanski
Date Posted: 15 April 2021 at 12:31am
Tinnitus Rex wrote:
Some recordings try to sound loud when played quietly.. This sounds terrible when you actually play it loud. | Totally agree, the loudness wars have ruined popular music genres.
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Posted By: KaphaSound
Date Posted: 15 April 2021 at 12:36am
Will look into Leq and by no means am I saying that dynamics don’t add to the impact! I am saying though that if a bass note say 40hz is on or off you will definitely notice it, and at the SPLs like those at the Village in the picture above you literally physically cannot miss it as if your whole body is physically touching the moving driver. At this point yes dynamics will still add to the experience but a continuous vibration won’t stop physically shaking you back and forth so there must be a point in terms of SPL at which your body begins to start going from say 100% a perceived audible sensation to 50% of the stimulus feels tactile and 50% audible.
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Posted By: KaphaSound
Date Posted: 15 April 2021 at 12:44am
Conanski wrote:
I'm sure we could put SPL measurements on it, but as you are aware that tactile feel doesn't seem to coorelate well with those measurements and that is in no small part because those measurements are essentially ignoring the dynamics. Take car audio for example, a single 12 or 15" sub in the boot can produce bass you can feel at SPLs still low enough to talk over, so it's more to do with effective coupling of driver/s to airspace IMO. The same thing happens in home audio but it takes more and bigger drivers because the air volume is larger, a typical home theater sound system with say 5" sats and a single 8-10" sub just doesn't produce much of that tactile bass regardless how loud it is played, but a pair of monkey coffins with 15" woofers makes things on the coffee table dance despite the fact that they don't go as low as the dedicated sub. |
Imo the reason for the difference in sensation across these examples often has to do with other objects in the room also resonating. In a car your whole seat vibrates making it feel like a stronger tactile experience likely at lower SPLs. Same thing with the home theater setup except this could be your couch or surrounding furniture. I’m more specifically interested in standing on solid ground outdoors with nothing else other than the stack of subs (and you aren’t physically touching the cabinets, the shear air pressure changes make you physically feel it).
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Posted By: Conanski
Date Posted: 15 April 2021 at 1:11am
I'll agree there can be some structural transmission of vibrations in certain environments but that can happen without it being felt too and I know enough to be able to differentiate.
If you have a stack do an experiment, set it up outside on solid ground and test the SPL level where you just start to feel the dynamics in the air, it's going to be relative to distance from the stack but I bet you will find it's a lot lower spl than what you might think and the bigger the stack the less spl required to feel it.
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Posted By: Elliot Thompson
Date Posted: 15 April 2021 at 1:22am
KaphaSound wrote:
Having experienced this I know that I don't need to compete with the giant 218 g-sub stack as it's about as physical as you'd really ever want it to be, but I do intend on throwing events where the focal point is still the physicality of the music (drumnbass, dub, dubstep, space bass etc...). Looking at the hornresp charts for the horn subs I'm planning I should be able to provide at least 130db continuous from about 33hz-80hz (+/- 3db) confidently, but all I really want to know is what's the threshold for a truly physical experience? Ideally I'm just looking for people's thoughts on a number here again in dBz as the other threads never really answered the question, and I’m guessing someone has taken measurements for this kind of thing?
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Your question could be
answered if one was playing solely in a fixed location at all times.
We are in the Sound Reinforcement market where the saying “It
depends” determines the direction on what methods to take since, we
are playing at lots of locations.
If you are playing
indoors, you can always use corners to energize the bass to give the
punters a greater feeling. Outdoors is more to wards bringing more
boxes in addition to, amplifiers than you think you will need. There
is a learning process in which, you must endure to graduate at the
level of, looking at a location and knowing ____ amount of subs in
addition to, ____ amount of amplifiers will give the punters a
tremendous feeling from 40 Hz – down.
The harsh reality is
the bulk of the home made horns on the market cannot make it to 30
Hz. This is why, those who want get to 30 Hz will use reflex
cabinets. Theses home made horns that you see many are using on the
market are good to around 45 Hz and struggle to make it to 40 Hz (a
lot of cone excursion). Physically, the horns are just too small to
approach anything significant in terms of SPL under 50 Hz.
A significant amount of
50 Hz will give one the sensation in addition to, giving one the
perception that they are hearing very low bass. It is also easier to
calculate higher dB figures at 50 Hz than an octave below.
In the Sound
Reinforcement Market, guys who have enough don't worry about how much
SPL is reading on a dB meter. They will know soon enough once, the
Police stops by with a dozen or so noise complaints, due to the bass.
So it goes back to
where you stand under the given circumstances. How many boxes in
addition to, amplifiers you are willing to use, to give the punters a
tremendous feeling, when it comes to bass?
Bear in mind, Horn
Response, like all simulators estimates the SPL from a 1 meter
perspective. You will need to use the inverse square law to determine
what your design will do when catering for the masses.
Best Regards,
------------- Elliot Thompson
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Posted By: citizensc
Date Posted: 15 April 2021 at 1:25am
Could this be related to distortion?
Distortion obviously increases perceived volume without increasing SPL.
So if you have two stacks of subs that SOUND like they are at the EXACT same SPL
Stack A: A single 18inch reflex putting out 133dB - Distorting because its being pushed
Stack B: 4 x 18 inch reflex putting out 136dB - Not distorting because it has heaps of headroom
Stack B is going to have more of a physical feeling than stack A simply because its achieving higher SPL but as mentioned it doesn't sound louder.
------------- https://www.facebook.com/voyager.system
@voyager_soundsystem
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Posted By: KaphaSound
Date Posted: 15 April 2021 at 1:40am
Conanski wrote:
I'll agree there can be some structural transmission of vibrations in certain environments but that can happen without it being felt too and I know enough to be able to differentiate.
If you have a stack do an experiment, set it up outside on solid ground and test the SPL level where you just start to feel the dynamics in the air, it's going to be relative to distance from the stack but I bet you will find it's a lot lower spl than what you might think and the bigger the stack the less spl required to feel it. |
I don’t have a stack yet***, and my reason for asking this question is to know if what hornresp is telling me is enough for what I’m trying to get out of it. That is the exact kind of measurement though that I was hoping others may have done, or just in general what people’s best guess is as to a number for a satisfying level of physicality.
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Posted By: KaphaSound
Date Posted: 15 April 2021 at 1:46am
Elliot I appreciate the depth of your comment there’s seemingly a lot to unpack when it comes to the physicality of bass. I am mostly still curious though as to a rough number that is to say if you are standing in a place outside where you are receiving a satisfactory level of physical bass, what might the SPL meter read in dBz?
Citizensc I definitely agree distortion will have a lot to do with why big stacks sound better and likely why they are more physical. Distortion definitely masks the fundamental, but as to how our bodies actual perceive this is a great question i.e if the distortion is somehow reducing the power of the fundamental not just masking it.
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Posted By: Conanski
Date Posted: 15 April 2021 at 2:50am
citizensc wrote:
Could this be related to distortion? |
That affects apparent SPL(more distortion sounds louder) but it doesn't translate to tactile feel. Take your example of a single sub and 4 subs, run them both at a measured 120dB@1m which is well withun the capabilities of even the single. The 4 sub stack will produce quite a bit more tactile feel because that cluster of drivers are a much more effective interface with the immediate air volume in front of them.
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Posted By: Elliot Thompson
Date Posted: 15 April 2021 at 2:56am
KaphaSound wrote:
Elliot I appreciate the depth of your comment there’s seemingly a lot to unpack when it comes to the physicality of bass. I am mostly still curious though as to a rough number that is to say if you are standing in a place outside where you are receiving a satisfactory level of physical bass, what might the SPL meter read in dBz? |
dB Meters read all
frequency's total level. Unless you turn off the tops (Note: An array
of tops will offer bass frequencies as well as they are full-range
cabinets), you cannot estimate the dB Level solely on the subs. You
can get 130 dB read from a SPL meter a few inches away from one sub.
You can also achieve 130 dB at front of the house with the tops
playing alone and, with the tops & subs playing.
dB meters will not tell
you what is satisfactory for bass from a physical standpoint. That is
human perception. All Sound men use their own judgement on what they
feel is satisfactory when applying bass. There is no set rule.
Think of it as
competition car sound systems owners. The SPL can be measured using a
dB meter. However, it is the overall reaction from the spectators,
that matters the most to the car sound system owner, when the
spectator(s) embark the bass.
Best Regards,
------------- Elliot Thompson
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Posted By: citizensc
Date Posted: 15 April 2021 at 3:08am
Conanski wrote:
citizensc wrote:
Could this be related to distortion? |
That affects apparent SPL(more distortion sounds louder) but it doesn't translate to tactile feel. Take your example of a single sub and 4 subs, run them both at a measured 120dB@1m which is well withun the capabilities of even the single. The 4 sub stack will produce quite a bit more tactile feel because that cluster of drivers are a much more effective interface with the immediate air volume in front of them. |
Has anyone actually tried this? Has anyone set up an SPL meter and compared the physicality of a single sub and multiple subs at the same SPL in a scientific way? The reason I am talking about apparent SPL is I suspect people are using their ears to compare loudness between systems and then using the term 'SPL' to describe this loudness but are being mislead by psycho acoustic effects. They are then saying 'x system sounded really loud but wasn't very physical, but y system wasn't that loud but I could really feel it' when in reality Y system was achieving higher SPL.
------------- https://www.facebook.com/voyager.system
@voyager_soundsystem
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Posted By: KaphaSound
Date Posted: 15 April 2021 at 3:24am
Elliot Thompson wrote:
dB Meters read all
frequency's total level. Unless you turn off the tops (Note: An array
of tops will offer bass frequencies as well as they are full-range
cabinets), you cannot estimate the dB Level solely on the subs. You
can get 130 dB read from a SPL meter a few inches away from one sub.
You can also achieve 130 dB at front of the house with the tops
playing alone and, with the tops & subs playing.
dB meters will not tell
you what is satisfactory for bass from a physical standpoint. That is
human perception. All Sound men use their own judgement on what they
feel is satisfactory when applying bass. |
I was actually not aware that spl meters factor in all frequencies at once I genuinely thought it read the loudest frequency at any given point in time but I’m glad if that is the case! Having said that though the kinds of levels that I’m aiming for would have the bass up anywhere from +20-30dBz compared to the tops, at which point surely the tops aren’t adding very much to the total spl level? Even so to the point about turning off the tops entirely that would be even better to compare to the hornresp sims!
Also citizensc I follow your logic but I would think that the tactile sensation would add far more to perceived total loudness than distortion. In fact I can pretty much guarantee that to be the case as I use a Subpac for my daily listening and I have noticeably turned the mains volume down by as much as 10db compared to what I used to listen at. Whenever someone tries it that hasn’t before with headphones on they end up screaming when they talk because they’ve completely lost the reference for what normal volume is.
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Posted By: Elliot Thompson
Date Posted: 15 April 2021 at 3:26am
citizensc wrote:
Conanski wrote:
citizensc wrote:
Could this be related to distortion? |
That affects apparent SPL(more distortion sounds louder) but it doesn't translate to tactile feel. Take your example of a single sub and 4 subs, run them both at a measured 120dB@1m which is well withun the capabilities of even the single. The 4 sub stack will produce quite a bit more tactile feel because that cluster of drivers are a much more effective interface with the immediate air volume in front of them. |
Has anyone actually tried this? Has anyone set up an SPL meter and compared the physicality of a single sub and multiple subs at the same SPL in a scientific way? The reason I am talking about apparent SPL is I suspect people are using their ears to compare loudness between systems and then using the term 'SPL' to describe this loudness but are being mislead by psycho acoustic effects. They are then saying 'x system sounded really loud but wasn't very physical, but y system wasn't that loud but I could really feel it' when in reality Y system was achieving higher SPL.
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I did that decades ago. It is the reason why, I only use double drivers per enclosure and not a single driver in each enclosure. The majority however, wants to extract every bit of SPL from the least amount of boxes as possible.
If one just wants more harmonic distortion, inserting a piece of gear that is known to offer distortion in the chain, will solve the issue.
Best Regards,
------------- Elliot Thompson
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Posted By: Elliot Thompson
Date Posted: 15 April 2021 at 3:34am
KaphaSound wrote:
Elliot Thompson wrote:
dB Meters read all
frequency's total level. Unless you turn off the tops (Note: An array
of tops will offer bass frequencies as well as they are full-range
cabinets), you cannot estimate the dB Level solely on the subs. You
can get 130 dB read from a SPL meter a few inches away from one sub.
You can also achieve 130 dB at front of the house with the tops
playing alone and, with the tops & subs playing.
dB meters will not tell
you what is satisfactory for bass from a physical standpoint. That is
human perception. All Sound men use their own judgement on what they
feel is satisfactory when applying bass. |
I was actually not aware that spl meters factor in all frequencies at once I genuinely thought it read the loudest frequency at any given point in time but I’m glad that is the case! Having said that though the kinds of levels that I’m aiming for would have the bass up anywhere from +20-30dBz compared to the tops, at which point surely the tops aren’t adding very much to the total spl level? Even so to the point about turning off the tops entirely that would be even better to compare to the hornresp sims!
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So you are pretty much going to have do some lengthy math on amplifier wattage and loudspeaker wattage to attain a + 20 dB to +30 dB of gain of bass over the tops.
Best Regards,
------------- Elliot Thompson
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Posted By: Conanski
Date Posted: 15 April 2021 at 5:31am
citizensc wrote:
Has anyone actually tried this? Has anyone set up an SPL meter and compared the physicality of a single sub and multiple subs at the same SPL in a scientific way? | I'm not aware of a specific example at the moment but this is based on transducer physics. The efficiency of a loudspeakers is a measure of it's ability to turn electrical impulses into acoustic impulses, this is quite a small number for direct radiators... about 4% for a driver with 98db sensitivity. That means only 4% of the electrical energy sent to the driver produces sound, the other 96% is wasted in heat. But every time the number of drivers is doubled you get a 3dB increase in sensitivity and a doubling of efficiency.Air is not very dense and low frequency wavelengths are hugh so the effective radiating area of a speaker system is the most significant factor for low frequencies, more direct radiating drivers or the use of acoustic couplers(horns) always produces better results than fewer speakers driven harder. We experience sound in two distinct ways.. as vibrations of the air and as pressure impulses, the two are related of course but require different approaches. Just about any size device can produce vibrations that are audible at higher frequencies but effective production of short term low frequency pressure impulses requires a radiating surface that is large relative to the listening space. Indoors this is easier to do but outdoors with no boundaries to contain the air the impulse decays quickly, so system requirements go way up.
citizensc wrote:
The reason I am talking about apparent SPL is I suspect people are using their ears to compare loudness between systems and then using the term 'SPL' to describe this loudness but are being mislead by psycho acoustic effects. They are then saying 'x system sounded really loud but wasn't very physical, but y system wasn't that loud but I could really feel it' when in reality Y system was achieving higher SPL.
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Yes that is a thing... happens all the time, a significant portion of listeners(and even DJs) are of the opinion that "it's not LOUD until it's distorting".
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Posted By: martinsson
Date Posted: 15 April 2021 at 8:59am
What is the relation between sound intensity (W/m2) and SPL (dB) and how do these couple to the physical sensation? I have been given to understand (told) that these are equal and follow eachother, but I cannot recall it being explained to me, the reason I mention this is a suspicion that they might differ and that this may explain why a greater coupling area (apart from directivity aspects) may render a more physical experience earlier on the SPL scale.
------------- Swedish Pro-fi diy-nerd - http://www.martinsson.cc/blog/" rel="nofollow - http://www.martinsson.cc/blog/
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Posted By: Elliot Thompson
Date Posted: 15 April 2021 at 4:58pm
martinsson wrote:
What is the relation between sound intensity (W/m2) and SPL (dB) and how do these couple to the physical sensation? I have been given to understand (told) that these are equal and follow eachother, but I cannot recall it being explained to me, the reason I mention this is a suspicion that they might differ and that this may explain why a greater coupling area (apart from directivity aspects) may render a more physical experience earlier on the SPL scale.
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How much experience you
have being exposed to high sound pressure levels will determine the
amount of tolerance you can handle under a given scenario. The person
with the least amount of experience, will be easily amazed by the air
pressure propagating from a single large woofer. Such individuals
have a lower threshold of expectations for bass. Those who have
experienced multiple large woofers playing at high sound pressure
levels, will have a higher expectation to reach their level of
satisfaction.
The above is not
limited to bass. It applies to everything in a human's life.
Best Regards,
------------- Elliot Thompson
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Posted By: Sonic the hedge
Date Posted: 15 April 2021 at 7:02pm
Elliot Thompson wrote:
How much experience you
have being exposed to high sound pressure levels will determine the
amount of tolerance you can handle under a given scenario. The person
with the least amount of experience, will be easily amazed by the air
pressure propagating from a single large woofer. Such individuals
have a lower threshold of expectations for bass. Those who have
experienced multiple large woofers playing at high sound pressure
levels, will have a higher expectation to reach their level of
satisfactionThe above is not
limited to bass. It applies to everything in a human's life
|
I don't fully agree - if you pardon the pun - as KaphaSound mentioned, there are base things that trigger a visceral response in humans. These are basic evolutionary instincts so are not in any way related to experience. Since it's essentially genetic there may however be variation in how it's felt between individuals.
KaphaSound wrote:
Tinnitus Rex I believe there are sensory cells (parcinian corpuscles to be exact) in our skin that enable us to feel low frequencies (likely evolved due to predators/natural disasters etc) so the whole human body really encompasses the full sense of hearing.
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In nature loud rumbles typically always signify danger e.g. earthquake, thunderstorm, stampede etc. As such human survival instincts that have evolved over millennia subconsciously trigger an increased state of alertness and perception. This is why loud bass sounds exciting and provokes an emotional response. This response does not diminish with repeated exposure.
While repeated exposure may develop an increased perception of tolerance for loud sounds I don't believe that the underlying reaction changes; only our conscious response to it.
In my experience a certain relatively fixed level of Bass will always provoke the same response, it's not like a drug addiction where more and more is needed due to desensitisation. IMO It's really just the level at which your skin and other body parts start to resonate. Below that point your skin doesn't pick anything up; much beyond that point additional levels have minimal effect and may actually simply become irritating, particularly if accompanied by excessive levels of midrange and HF.
loud sound also triggers tympanic reflex which protects the eardrum from overload. This response is relatively slow - again probably because the ear damaging sound levels that exist in nature are all low in frequency, so our ears are evolved to protect against such sounds. But it does mean that the ear self-regulates in the presence of loud bass, which also reduces the level of higher frequencies reaching the eardrum incidentally.
Just my opinion/experience. Of course everyone's senses are slightly different so each individual will have a different experience. Sound is an inherently subjective experience so it important not to generalise or make assumptions about what's 'correct', IMO.
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Posted By: KaphaSound
Date Posted: 15 April 2021 at 9:19pm
Couldn’t agree more that bass heads will have a much higher tolerance for their insides being rattled than opera connoisseurs. Completely agree as well with what Sonic is saying that there is a fixed level at which point your skin starts to really resonate and vibrate, and although you can acclimatize to that sensation it is very obviously noticeable if it’s there or not, as if someone is literally hitting you with a pillow for example 40 times a second. I’ve also been trying to go down the rabbit hole of converting spl to force and then trying to find a list of examples of forces to see if for example 120db equals being hit by a paperclip, but this has not been fruitful understandably because it is very dependent on high vs low frequencies.
I would still think though that many members here have taken many SPL measurements without crazy distortion levels as citizensc pointed out and have a fairly consistent idea of what they consider a satisfactory level of tactile sensation. I know this will differ from person to person but I’m really still just curious what everyone’s personal satisfactory levels are.
So far between Reddit and this thread there have been north of 70 comments and only 1 comment gave a number: 100dBc “at 6' with a D2 (about 70hz) note will rattle you but a D1 (about 37 hz) is def better feeling”. So that’s at most 105-110dBz. I’ve heard in this forum before that 115dBz isn’t really all that impressive, so my guess is minimum 115+ might be closer to what I’d like to be able to provide for maybe 50-200 people, with the real speaker freakers at the front getting a good bass bath. I definitely intend on taking this kind of measurement when I do have a stack and no noise restrictions, but until then the idea is to make sure I’ll be able to provide enough so any other thoughts on a rough number would be greatly appreciated!
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Posted By: Tinnitus Rex
Date Posted: 15 April 2021 at 9:30pm
Perhaps I could sell a very expensive box with two LEDs on it one RED that means "insufficient" and one GREEN that means "sufficient".( this would really confuse DJs).. Remenber ,"no gain without pain".
------------- "couldn't we just like... use headphones?"
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Posted By: toastyghost
Date Posted: 15 April 2021 at 9:37pm
martinsson wrote:
What is the relation between sound intensity (W/m2) and SPL (dB) and how do these couple to the physical sensation? I have been given to understand (told) that these are equal and follow eachother, but I cannot recall it being explained to me, the reason I mention this is a suspicion that they might differ and that this may explain why a greater coupling area (apart from directivity aspects) may render a more physical experience earlier on the SPL scale.
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Efficiency is a metric of acoustic power output, which translates to sound intensity. The acoustic sound power of a loudspeaker is given for a spherical field - it has no directional component. Sensitivity is taken on-axis, and is subject to directivity. A less efficient loudspeaker may have a larger sensitivity value on the spec sheet because of the directivity.
You can’t really talk about output without understanding both, and you can convert between the two once you do.
Larger stacks of subs will radiate differently than smaller ones. There’s a change in directivity, but also a change in acoustic impedance.
I forget who asked about studies but the short answer is yes, a fair few tests along those lines and plenty of others. If you don’t want to hit up Google Scholar, then I’d suggest getting some of those things called books. They might not be cool, but this is a field of science and as such there’s quite a lot of stuff written down and looking at some equations and graphs will do a lot more for your understanding than the occasional inebriated subjective assessment of apples and oranges.
The one place that research has lacked in somewhat is large scale low frequency noise propagation for music, at gig levels. The most comprehensive investigation into whole body vibration belongs to NASA, and can be easily found online. It’s a bit of a monster but there are some fun experiments contained within.
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Posted By: Elliot Thompson
Date Posted: 15 April 2021 at 9:58pm
Sonic the hedge wrote:
Elliot Thompson wrote:
How much experience you
have being exposed to high sound pressure levels will determine the
amount of tolerance you can handle under a given scenario. The person
with the least amount of experience, will be easily amazed by the air
pressure propagating from a single large woofer. Such individuals
have a lower threshold of expectations for bass. Those who have
experienced multiple large woofers playing at high sound pressure
levels, will have a higher expectation to reach their level of
satisfactionThe above is not
limited to bass. It applies to everything in a human's life
|
I don't fully agree, if you pardon the pun as KaphaSound mentioned there are base levels that trigger a visceral response in humans. These are basic evolutionary instincts so are not in any way related to experience. Since it's essentially genetic there may however be variation in how it's felt between individuals.
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The keyword is Tolerance. The level of tolerance varies from one's personal experience.
Best Regards,
------------- Elliot Thompson
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Posted By: martinsson
Date Posted: 16 April 2021 at 9:08am
Toastyghost, you are right, and there has been a couple of books on my desk over the years, mostly before internet though to be honest, and mainly on the topic of how to design boxes from t/s parameters.
But for sure there still is alot left to learn from books, take Leo. L. Beraneks acoustics for example, I actually have given it a try but it was a bit to heavy for me at the time, perhaps I should give it try again now that a bit more time has passed.
Sorry for drifting of topic, I think maybe my previous experiences are clouding my judgment here, my experience tells me more boxes (greater coupling area) even if at subjectively the same levels as half the number boxes does give another sensation physically in favour of the first case, but the keyword here is subjectively, chanses are the the levels differed alot and the lack of distortion or increase in range or both may have fooled me into thinking levels where similar.
This is a very old memory, standard 2241 218 br, we upped the number of boxes per side from two to four but keept the rest of the system intact, and made sure we stayed on the right side on the levels in both cases, it sounded very different in the low end, more solid and more in the chest/stomach.
------------- Swedish Pro-fi diy-nerd - http://www.martinsson.cc/blog/" rel="nofollow - http://www.martinsson.cc/blog/
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Posted By: bob4
Date Posted: 18 April 2021 at 9:43pm
martinsson wrote:
This is a very old memory, standard 2241 218 br, we upped the number of boxes per side from two to four but keept the rest of the system intact, and made sure we stayed on the right side on the levels in both cases, it sounded very different in the low end, more solid and more in the chest/stomach.
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The first time ever that bass made me want to move and dance was a similar setup. Outdoors, four jbl double 18" reflex bins stacked per side, powered by a bunch of CA18. It could be felt from half a mile away... ....
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Posted By: toastyghost
Date Posted: 19 April 2021 at 11:32am
This paper answers your question, for both dBZ SPL (at the listener) in 1/3rd octave bands, and how that translates to physical acceleration for those same frequencies.
https://www.aes.org/e-lib/browse.cfm?elib=20383" rel="nofollow - https://www.aes.org/e-lib/browse.cfm?elib=20383
The terms you need to use are Whole Body Vibration; it’s different for each person as we all have an individual Body Related Transfer Function. It doesn’t seem to matter if you’re fat or not.
I noticed you mentioned trying to convert sound pressure to physical measurements. That’s not difficult, sound is often measured or calculated in Pascals and converted.
They had 28 test subjects who were fitted with six accelerometers, at key points for conduction like the chest and shoulders. It’s a bloody good paper, frankly. They only used a single dual 18” French sub but that’s absolutely fine in the test environment used.
Here are the juicy bits:
Be aware these are taken out of context before you throw judgement! If you haven’t read the methodology and prior research, then you may find it hard to put aside your subconscious bias.
I won’t share the full paper, but if you’re really serious about answering these sorts of questions then the AES journals are a damn good place to start looking. Even if you don’t get everything that’s being discussed, you then have jumping off points for more research and reading, or to ask more specific questions. It isn’t ‘cheap’ but I found I got my money’s worth very quickly. Not just on journal access, but the several meets and education sessions every month.
As an aside I’m often quite shocked how many supposedly professional ‘engineers’ don’t seem to want to spend the very reasonable annual AES membership fee. I guess it doesn’t fit with the stereotype of repeating the same old waffle in a grumpy manner? 😅
If you’re a student, it’s damn cheap and takes 5 years to hit full price. Take advantage of that situation if you can!
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Posted By: madboffin
Date Posted: 19 April 2021 at 5:41pm
What's dBz?
All the sound measuring equipment I have used over the last 50 years has been fitted with various combinations of A, B, C, Lin (and sometimes D) scales.
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Posted By: toastyghost
Date Posted: 19 April 2021 at 6:41pm
madboffin wrote:
What's dBz?
All the sound measuring equipment I have used over the last 50 years has been fitted with various combinations of A, B, C, Lin (and sometimes D) scales.
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You could probably have googled it in the time it took to post that...
Z Weighting
[Z-weighting is a flat frequency response of 10Hz to 20kHz ±1.5dB. This response replaces the older "Linear" or "Unweighted" responses as these did not define the frequency range over which the meter would be linear.
Z-weighted measurements are expressed as dBZ or dB(Z). |
From noisemeters.com
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Posted By: KaphaSound
Date Posted: 20 April 2021 at 3:05am
Wow thank you toastyghost! This is exactly the kind of thing I’m looking for and to top it all off it’s even in dBz by frequency. I know AES have tons of papers but this one strikes me as one of the more interesting (alteast personally). I have actually done some research into body resonances which show some interesting results as far as where you may predominantly feel certain frequencies and how your build may affect this, but the threshold was never particularly clear.
From the abstract: “ Perceptual tests identified a frequency dependent threshold of 94-107dBZ required to induce a perceivable whole-body vibration.” I don’t think the answer gets more clear than that so again thank you! Just a few follow up questions: I’m assuming the black lines in the grey bars are the variations between subjective results? So what is the black line graph since it doesn’t look like an average of the grey bar trend? And is the acceleration measurement a result of both frequency and spl (apologies if this is a basic question)?
My guess based on this info is that ~130dbz should be enough for a physical experience over a space big enough for 50-200 people or so. I am hoping these horns will actually be able to hit 140 continuous down to about 32hz in groups of 4, but I’ll have to take measurements to confirm.
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Posted By: imageoven
Date Posted: 20 April 2021 at 9:30am
toastyghost wrote:
madboffin wrote:
What's dBz?
All the sound measuring equipment I have used over the last 50 years has been fitted with various combinations of A, B, C, Lin (and sometimes D) scales.
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You could probably have googled it in the time it took to post that...
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I'm glad he did ask, I was assuming dBz was street slang...
------------- Keep pushing on, things are gonna get better.
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Posted By: toastyghost
Date Posted: 20 April 2021 at 10:46am
KaphaSound wrote:
Wow thank you toastyghost! This is exactly the kind of thing I’m looking for and to top it all off it’s even in dBz by frequency. I know AES have tons of papers but this one strikes me as one of the more interesting (alteast personally). I have actually done some research into body resonances which show some interesting results as far as where you may predominantly feel certain frequencies and how your build may affect this, but the threshold was never particularly clear.
From the abstract: “<span style="caret-color: rgb77, 77, 77; color: rgb77, 77, 77; font-family: "Roboto Condensed", sans-serif; font-size: 17px; -webkit-tap-highlight-color: rgba0, 0, 0, 0; -webkit-text-size-adjust: 100%;"> Perceptual tests identified a frequency dependent threshold of 94-107dBZ required to induce a perceivable whole-body vibration.</span>” I don’t think the answer gets more clear than that so again thank you! Just a few follow up questions: I’m assuming the black lines in the grey bars are the variations between subjective results? So what is the black line graph since it doesn’t look like an average of the grey bar trend? And is the acceleration measurement a result of both frequency and spl (apologies if this is a basic question)?
My guess based on this info is that ~130dbz should be enough for a physical experience over a space big enough for 50-200 people or so. I am hoping these horns will actually be able to hit 140 continuous down to about 32hz in groups of 4, but I’ll have to take measurements to confirm.
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No worries, but if you can't find other interesting things on there, you aren't trying hard enough
You might like this one, for example... https://www.aes.org/e-lib/browse.cfm?elib=19179
The black line on the first graph is for the right axis, which is the vibration threshold, the whiskers belong to that to show the range of data points in that 'bin'. The bars are for the left axis.
You might be surprised what real-world continuous output is for subs, especially with modern music. You're going to be thermally limited with a FLH. Consider the temperature rise. MEASURE IT if you can. Look up the toaster test.
This is one of those places where the old school don't really seem to 'get' how modern subs using low tunings/big ports with high BL drivers and Class D amps work in tandem to produce much more consistent results at low and high drive levels.
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Posted By: martinsson
Date Posted: 20 April 2021 at 3:57pm
True, yet somehow I can't let go of my perception (note the wording) that your average large format linearray with the standard ~30Hz tuned 218 BR sub complement just does not seem to have the same impact in the 80-120Hz range, sure there is sub, loads of it even, but I perceive it to lack kick and definition bass range compared to "old school" flh and horn setups, stay turbosound flashlight for example.
Some of this is down to frequency content but not all I believe.
------------- Swedish Pro-fi diy-nerd - http://www.martinsson.cc/blog/" rel="nofollow - http://www.martinsson.cc/blog/
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Posted By: fatfreddiescat
Date Posted: 20 April 2021 at 5:26pm
martinsson wrote:
True, yet somehow I can't let go of my perception (note the wording) that your average large format linearray with the standard ~30Hz tuned 218 BR sub complement just does not seem to have the same impact in the 80-120Hz range, sure there is sub, loads of it even, but I perceive it to lack kick and definition bass range compared to "old school" flh and horn setups, stay turbosound flashlight for example.
Some of this is down to frequency content but not all I believe. |
Possibly due to the 80Hz area being the typical crossover region, usually using 4th order slopes and non linear phase due to the delay that would be incurred if using linear phase filters. A 4th order filter would mean the lows are a full cycle behind the high's and likely a non perfect cancellation of the filters 'ringing'?
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Posted By: KaphaSound
Date Posted: 20 April 2021 at 5:29pm
Thermal limitations are definitely a concern of mine with a FLH considering no ventilation for the rear chamber, however in all the sims I’ve run I’m hitting xmax/xvar at about a 1/4 of the driver’s peak power rating, meaning I’d be running continuous at even less than that (200-400watts into 8ohm) so I’m hoping the sheer efficiency essentially prevents thermal compression from having a big influence on output.
That second paper is also very interesting and backs the idea that more bass could actually reduce the preferred total dBa volume level. I certainly intend on trying to push the limits here as far as running the mid tops low say ~90-95 and the subs closer to 120-130. Thanks again toastyghost!
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Posted By: toastyghost
Date Posted: 20 April 2021 at 9:52pm
fatfreddiescat wrote:
True, yet somehow I can't let go of my perception (note the wording) that your average large format linearray with the standard ~30Hz tuned 218 BR sub complement just does not seem to have the same impact in the 80-120Hz range, sure there is sub, loads of it even, but I perceive it to lack kick and definition bass range compared to "old school" flh and horn setups, stay turbosound flashlight for example.
Some of this is down to frequency content but not all I believe. |
There are many more significant factors to tonal quality than frequency response. Horns are acoustic impedance matching devices. All of them, to varying degrees. Start your investigation there - warning, maths ahead.
martinsson wrote:
Possibly due to the 80Hz area being the typical crossover region, usually using 4th order slopes and non linear phase due to the delay that would be incurred if using linear phase filters. A 4th order filter would mean the lows are a full cycle behind the high's and likely a non perfect cancellation of the filters 'ringing'? | That’s a non-issue, even if your intuition was correct. Delay is commonplace, as are allpass filters. If your subs are a lap behind, then you fire your system tech. Although I see that far more often than I would like. Another area where I’m fairly sure this comes down to people repeating what they’ve seen someone else do, rather than doing some maths and checking things over.
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Posted By: Elliot Thompson
Date Posted: 20 April 2021 at 10:09pm
martinsson wrote:
True, yet somehow I can't let go of my perception (note the wording) that your average large format linearray with the standard ~30Hz tuned 218 BR sub complement just does not seem to have the same impact in the 80-120Hz range, sure there is sub, loads of it even, but I perceive it to lack kick and definition bass range compared to "old school" flh and horn setups, stay turbosound flashlight for example.
Some of this is down to frequency content but not all I believe. |
There are lots of
reasons behind this. Here are few. Folded Horns of that era were bass
bins in which, were good to around 60 Hz. Also, drivers were more
efficient when you compare woofers designed solely for horn-loading
from that era to today.
In the Philippines,
Cerwin Vega copies are in abundance. Their set-ups offer a very
strong punchy/impactful Bass (Nothing below 60 Hz). The video below
shows what you can achieve playing 60 Hz - 180 Hz from a large stack of
horn-loaded Bass Bins.
The Sound Systems in
the Philippines generally build their own amplifiers in addition to,
design their own woofers.
Having a good understanding of your music content will steer you in the direction of Horns or Reflex.
Best Regards,
------------- Elliot Thompson
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Posted By: fatfreddiescat
Date Posted: 20 April 2021 at 11:32pm
toastyghost wrote:
fatfreddiescat wrote:
True, yet somehow I can't let go of my perception (note the wording) that your average large format linearray with the standard ~30Hz tuned 218 BR sub complement just does not seem to have the same impact in the 80-120Hz range, sure there is sub, loads of it even, but I perceive it to lack kick and definition bass range compared to "old school" flh and horn setups, stay turbosound flashlight for example.
Some of this is down to frequency content but not all I believe. |
There are many more significant factors to tonal quality than frequency response. Horns are acoustic impedance matching devices. All of them, to varying degrees. Start your investigation there - warning, maths ahead.
martinsson wrote:
Possibly due to the 80Hz area being the typical crossover region, usually using 4th order slopes and non linear phase due to the delay that would be incurred if using linear phase filters. A 4th order filter would mean the lows are a full cycle behind the high's and likely a non perfect cancellation of the filters 'ringing'? | That’s a non-issue, even if your intuition was correct. Delay is commonplace, as are allpass filters. If your subs are a lap behind, then you fire your system tech. Although I see that far more often than I would like. Another area where I’m fairly sure this comes down to people repeating what they’ve seen someone else do, rather than doing some maths and checking things over. |
Somehow the quotes are back to front! Re 360 degree lag for the lows, for 4th order it is a 12.5ms delay to adjust for, fine if that is acceptable to add to the system latency, then I agree that allpass and delay would work, there are other IIR alternatives as I'm sure your aware. There have been many discussions about the difference between how horn loaded systems thump like nothing else, other than roll off slopes and the use of crossovers in the 'kick' area is that power factor in acoustical terms may play a part? Bummer that Bowlers didn't come off last Feb as I was booked for one of the other rooms and was hoping to hook up.
Edit: also meant to mention transient response.
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Posted By: carlosdelondres
Date Posted: 11 May 2021 at 1:52pm
Interesting thread :)
Any thoughts on the pulse quickeing effect of certain alignments?
I've
spent most time listening to boxes I've owned/build, and from
terrahorns, SS15 tapped horns, 2x18 BPH and others, a pair of dual 5"
(really) PPSL ported plenum 6th order bandpass boxes have a definite
pulse racing effect, even though they don't go much below 50hz or over
about 110dB.
It's quite an 'exciting'
effect, though those boxes are maybe a little fatiguing on the ear after
an hour or two. Almost heart racing stage fright type anxiety. Not the
same as kick chest compression, more a psycho acoustic effect I
thought especially given the low level of the output.
Any thoughts on this and how it might contribute to the urgency/physicality of bass reproduction?
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Posted By: Andylaser
Date Posted: 12 May 2021 at 1:28am
fatfreddiescat wrote:
https://www.ted.com/talks/evelyn_glennie_how_to_truly_listen/up-next#t-2786" rel="nofollow - https://www.ted.com/talks/evelyn_glennie_how_to_truly_listen/up-next#t-2786
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Thats excellent. Thanks.
------------- "music so loud, that if we move in next door to you; your lawn will die" - Lemmy
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Posted By: KaphaSound
Date Posted: 12 May 2021 at 3:24am
carlosdelondres wrote:
I've
spent most time listening to boxes I've owned/build, and from
terrahorns, SS15 tapped horns, 2x18 BPH and others, a pair of dual 5"
(really) PPSL ported plenum 6th order bandpass boxes have a definite
pulse racing effect, even though they don't go much below 50hz or over
about 110dB.
It's quite an 'exciting'
effect, though those boxes are maybe a little fatiguing on the ear after
an hour or two. Almost heart racing stage fright type anxiety. Not the
same as kick chest compression, more a psycho acoustic effect I
thought especially given the low level of the output.
Any thoughts on this and how it might contribute to the urgency/physicality of bass reproduction?
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I believe this comes down to group delay. Sealed/open baffle will always be the fastest from what I gather but that’s not usually going to efficiently get loud enough for an intense physical sensation. Ported seemingly always has a fair bit of group delay at tuning, and horns seem to be the most variable with group delay also gradually increasing around tuning. More group delay gives you a more sluggish response which I believe is what you mean by the pulse effect, but there is certainly a debate around how much is perceptible especially in the 30hz range and below.
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Posted By: fat_brstd
Date Posted: 12 May 2021 at 4:49am
toastyghost wrote:
This paper answers your question, for both dBZ SPL (at the listener) in 1/3rd octave bands, and how that translates to physical acceleration for those same frequencies.
https://www.aes.org/e-lib/browse.cfm?elib=20383" rel="nofollow - https://www.aes.org/e-lib/browse.cfm?elib=20383
The terms you need to use are Whole Body Vibration; it’s different for each person as we all have an individual Body Related Transfer Function. It doesn’t seem to matter if you’re fat or not.
I noticed you mentioned trying to convert sound pressure to physical measurements. That’s not difficult, sound is often measured or calculated in Pascals and converted.
They had 28 test subjects who were fitted with six accelerometers, at key points for conduction like the chest and shoulders. It’s a bloody good paper, frankly. They only used a single dual 18” French sub but that’s absolutely fine in the test environment used.
Here are the juicy bits:
Be aware these are taken out of context before you throw judgement! If you haven’t read the methodology and prior research, then you may find it hard to put aside your subconscious bias.
I won’t share the full paper, but if you’re really serious about answering these sorts of questions then the AES journals are a damn good place to start looking. Even if you don’t get everything that’s being discussed, you then have jumping off points for more research and reading, or to ask more specific questions. It isn’t ‘cheap’ but I found I got my money’s worth very quickly. Not just on journal access, but the several meets and education sessions every month.
As an aside I’m often quite shocked how many supposedly professional ‘engineers’ don’t seem to want to spend the very reasonable annual AES membership fee. I guess it doesn’t fit with the stereotype of repeating the same old waffle in a grumpy manner? 😅
If you’re a student, it’s damn cheap and takes 5 years to hit full price. Take advantage of that situation if you can! |
So 63hz-75hz is really where the sweet spot is in terms on shaking the audience, no wonder the reggae boys love the scoops so much
------------- Adrians Wall Sound System Melbournes Rootical Warrior Roots - Dub - Steppers
http://www.facebook.com/adrians.wall" rel="nofollow - facebook page
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Posted By: 0krizia
Date Posted: 13 May 2021 at 4:47pm
The lower the frequency, the more physical the sound is. correct me if im wrong... Most sound engineers tend to aim for a sound signature with a gradual increase in spl the lower the frequency is in the bass region. I have spoken to multiple sound engineers on concerts I have been on and most in Norway tend to aim for an average of 100db above 100hz at their location during the concert. Add the typical 10-15db boost at the lowest frequencies many engineers apply and we are at 110 -115 db, by being 4 times closer to the stage than the sound engineer, the spl increase with an additional 12 db, add an additional 6db for dynamic range and the level is 128-133 in the bass and sub region. At this level, it can definitly be felt. The challenge is to achive this level of soundpresure between 30-38hz, it demands a serious system.
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