On Sun, 02 Feb 2014 19:26:19 -0800, Salmon Egg
wrote:
>In article <9g6re9dshlal5edblj2hapmsu1dea1df43@4ax.com>, krw@attt.bizz
>wrote:
>
>> >Although sound although sound is a longitudinal (scalar) pressure wave
>> >in the air, the theory has much similarity to that of antennas. I have
>> >never heard talk of multipath problems with hearing aids. I do not
>> >understand how two small microphones space a small fraction of a
>> >wavelength apart can be processed to give directional patterns. U can
>> >understand that spacing BETWEEN ears can give rise to interferometric
>> >cues. When I asked if the two aids exchange audio information, the
>> >answer was no.
>>
>> We've been working with phased microphone arrays recently. It was
>> amazing to see that the recommended spacing for one solution was 11mm.
>> You're right, it doesn't make much sense, given common knowledge of
>> antennas.
>
>You would think that it would depend upon the frequency. I would be very
>surprised if there were no experiments listed in the literature that
>looked into how well the stereo effect was sensed as a function of
>frequency.
Yes, frequency dependence seems natural. These are audio frequency
microphones, 20-20K, so we're talking about a *lot* less than a
wavelength.
>Becaus sound is longitudinal. could it be that hearing aids process
>amplitude rather than phase for directional discrimination? I can
>picture two microphones angled with respect to each other with a
>difference of transduced amplitude because one is hit normally by the
>sound while the other is hit obliquely. It is sort of like the
>dependence of illumination of a surface being affected by the angle of
>incidence. Think Lambert's law.
Nope. These microphones are coplanar.
--- SoupGate-Win32 v1.05
* Origin: you cannot sedate... all the things you hate (1:229/2)
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