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Miniature Speaker Selection

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JoshuaGates View Drop Down
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    Posted: 24 June 2016 at 4:56am
Hi Everyone,

Just working on a new project with a probe that will be inserted into a void space (maybe defined as a 2m cube).
The probe will be inserted through a 35mm hole so that is the definition of miniature speaker I am going for.
The operator will be able to use a microphone from their laptop which will be outputted to the miniature speaker in the void which I will probably just hook up to a 3.5mm audio jack.

The question then becomes how do I select the miniature speaker?
I was looking on RS Components for speakers within the size requirement with the highest rated power (1.5W best I could find)
however the frequency range is then limited to 7kHz and I understand audible sound goes to 20kHz. I'm trying to avoid obtaining sound similar to that of earbuds on max where it's too quiet so more toward like a cellphone on speaker phone hence was looking at the rated power. Any advice on this project would be brilliant.

Trying to google my queries just brings about links to do with public speaking so thought making a more detailed post in the right environment could help me out.
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imageoven View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote imageoven Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2016 at 9:58am
What are you trying to achieve?

What sort of probe are you talking about?

Do you want to produce a flat frequency of sound inside a sealed space? does the volume matter?
Keep pushing on, things are gonna get better.
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JoshuaGates View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JoshuaGates Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2016 at 12:32pm
Trying to achieve transmission of human voice into the void space to talk to potential injured persons.
Designing a probe kind of mechanism that one inserts into the void and transmits the speech.
Want to produce the operators voice through the speaker so it's loud enough to hear within the space and it is audible.

Hope this information helps. Thanks
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studio45 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2016 at 5:21pm
Without resorting to - as you say - using hard-to-get OEM parts from phones, tablets or laptops, you might have more success with a "speaking tube" type of device: ie, coupling a conventionally-sized loudspeaker to a somewhat flexible but internally hard-surfaced tube and inserting that into the hole. 
This should not give you insurmountable issues with frequency response, the speech frequencies are commonly defined as 300 to 3000Hz so as long as you can achieve that you should be able to transmit intelligible speech. Something that could get to 7kHz would sound positively hi-fi! 
If you can get clever with a DSP unit, you might even be able to "equalise" the speaker/tube combination to help cancel out reflections and resonances. 
Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA
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mini-mad View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mini-mad Quote  Post ReplyReply Direct Link To This Post Posted: 24 June 2016 at 6:10pm
so you ONLY want to able to play the vocal range then as suggested use the idea of a larger speaker driver and just using a 35mm throat to play it down... the same sort of way a compression with a 3inch coild plays through a 2inch throat into a horn. yours will just be a long throat with no horn at the end!

as long as you not playing full range music down it you should be ok... may be a bit directional too.

If it sounds like a gorilla is trying to escape, turn it down.
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JoshuaGates View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JoshuaGates Quote  Post ReplyReply Direct Link To This Post Posted: 26 June 2016 at 2:01am
Hey have considered a speaking tube with the larger conventional speaker but am more looking toward having the system integrated in the probe but thanks for the idea. So the way I sort of want to achieve this has the speaker inserted through a 35mm hole so diameter must be less than that. 

Have looked into my options a bit and have selected this speaker with this amplifier (links below). I chose the amplifier due to its size and being pre-built and providing up to 1.4W and the speaker due to its 28mm diameter and 1.5W rated power. Are these valid thoughts behind the selection of the above two components?

https://www.sparkfun.com/products/11044

http://nz.rs-online.com/web/p/miniature-speakers/7564618/

Would the incoming signal from the laptop microphone port just be sent using an audio jack with open connections to attach to the amplifier board? Or could I achieve the same thing with an off the shelf microphone, cut off the audio jack connection and then attach that to the amplifier board? I'd want to make it press to talk so I could either do that via software or a button depending on the option I choose above correct?

Sorry for all these questions but am rather new to all these concepts and if the questions don't make sense or you need more information just let me know as I realise it makes sense to me when I ask but I might not convey that all too well. Also sorry if I am not allowed to post those links but just wanted to give reference as to what I was describing.

Thanks
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