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"sometime in the late 80's after I' d published an article on the comparative anatomy of the cochlea and audition, I noticed that "Action Ear, Inc." had come out with percussive-sound inhibiting ear muffs for shooters. The ear muff had a little microphone build in which cut-off at the high decibel level of a gun shot, but remained functional for conversation and other ambient sound (such as echos) at lower decibel levels. I knew at that moment that I would at last be able to hear the close object echos that bats can hear, but we can't. Because of the "precedence effect" - or "law of the first wave front"- by which a nearby sound - like a shout or clapped hands - inhibits the perception of its' reflected echo for a short period of time, essentially making it impossible to hear an echo in anything under 20 feet or so. One of the ways bats get around this, I am told, is by tightening their tympanic membrane (or spadial muscle?) when they cry at echo-locating frequencies thus partially deafening themselves for just long enough to overcome this effect and allow the perception of an echo from a nearby object. Sure enough, it worked. The shooter's muffs functioned the same way. It was great fun. I could now hear echos of loud claps or clicks in a closed room as could anyone else who tried on the shooters muffs. When I demonstrate this to a patent attorney, I told him to clap you hands three times, getting louder each time. With the first two claps he registered nothing, but at number three he exclaimed" It came from my secretary's office!". I thought at the time this might be useful for the blind, and, indeed, felt myself more secure walking around a room with my eyes shut when I had them on and was making clicks with a clicker, but that's as far as I took it."
Very cool information DirectorX, appreciate the repost. And yeah what Thomas said about being able to do it all from a computer should work great, especially for testing various variables before intergrating the final bits into a smaller chip.
You can source some what are called "binaural mics" for not too much, they will have great quality compared to any cheap mic you might otherwise use, and most decent(read:over 20 dollar) speakers will be able to reproduce this well enough to show 3d space. And you are going to want to go with some mics and drivers that go up to at least 20k, even though you might not hear above that a driver can go up to 30k will perform far more accurately at 20 than those that only go to 20. The high ranges would be very important to 3d hearing as high pitches are more directional. Though i'm sure you already know most if not all of this.
But yeah youll probably want to do a lot of studying on acoustics as well as binaural audio as proper binaural mic technique will be important for getting really exact hearing when passing though mic and driver.
As a side note hear is a holophonic recording ive done(wrote binaural but realized later it is technically holophonic) as well as a really good example of how accurate things can get.
Director glad you found my information useful. I believe I have a decent amount of knowledge in acoustics,sound, hearing, audio and the like so if you have anymore question ask away.
You can get audacity for free audio editing.
Okay i'm now wondering how much of the precedence effect is mental and how much is physical.
Mostly i'm wondering about how phasing effects this and if we could make our devices much smaller by just making use of phase. Ill get to the application after I explain my theory.
So talking in a large room vs a small one, first, obviously in the large you would hear echos while the small you wouldn't, the precedence effect claims this is all mental, but i'm not so sure. Now the second difference in talking in a small vs large room is the volume of your voice, to both you and others. Whats happening obviously is the waves are bouncing off the walls and reinforcing your voice. At the first bounce they align in phase with the original soundwaves, but the echos you hear have traveled and bounced long enough that they are somewhat out of phase with the original sound. This creates a sound which does not reinforce the original sound but rather comes to your ears as a sound of its own. So the phase of sound would change if your ears "listen" the sound or not. Lenth of time in air and bouncing affects the phase of the sound.
So I was thinking about a very very simple device which would be a microphone, amp, and small speaker where the amplifier would be made to flip the polarity of the sound, which could be done simply with a balanced circuit that has it's wires flipped somewhere or I think most op amps have a built in section if you'd want to do this. The sound the speaker produced would be directly out of phase with the sound the microphone picks up. These would go over your ears like headphones. Though i'm starting to doubt myself as I write this, this might just act like a noise canceling headphone. Or maybe if we could design a circuit that didn't just flip the phase but moved it half way out of alignment. This wouldn't necessarily cancel out the sound and it also wouldn't reinforce the sound. In theory this would allow room sound to become unique rather than just adding to the original sound. So the room could be heard separately and almost immediately.