Topic: Looking for a high quality Omni?

[wbrisette]

I have no dout that the Sanken CO-100 K microphone is a wonderful microphone, but nor hearing phisiology nor psychoacoustics support that the extended frequency range 20.000-100.000 Hz) is responsible of it. You have guessed well, this microphone is not for me, perhaps for nature recordists interested in bat ultrasounds.

I think they are going after the classical music audience with this mic. If I recorded more of that market, I would certainly be going after a pair of these myself. But, they simply don't have the SPL that I need when I use omnis for amplified music, and for the few times a year I do classicial and acoustical shows, I can't see spending $4K.

Wayne

[WiFiJeff]

That said, the upper frequency limit of hearing is not somewhat arbitrary, but a scientific data totally stablished through neurophysiological recordings. There is no sound perceived  beyond, lets say, 20.000 Hz, as there is no vision in absolute darkness.

This little theoretical tract would be to the point if all we were listening to were monophonic sine waves.  Then the 20 kH hearing limit (probably even lower than that for most of us) would be indisputable.  But lots of what the ear does is inconveniently non-linear.  Also, we want to reproduce a stereo sound stage, and arrival times at left and right ear are an important cue.  Tests have shown that the ear can differentiate very short differences in arrival time, and I have seen it suggested that recording at 192 kH is actually warrented to preserve these cues, even if we can't hear 96 kH sine waves. 

Jeff

[Von Recklinhausen]

This little theoretical tract would be to the point if all we were listening to were monophonic sine waves.  Then the 20 kH hearing limit (probably even lower than that for most of us) would be indisputable.  But lots of what the ear does is inconveniently non-linear.

I have been too naïve thinking that it could be better explained considering a simple sinusoidal wave. But we can dive deeper.

Over 100 years ago, the physicist Georg Ohm, the same who gave his name to Ohm's law, recognized the basic principle governing the function of the ear. He proposed that complex sounds are broken down into simple and discrete vibrations for subsequent analysis by the brain. In effect, Ohm suggested the ear performs a type of analysis described several years earlier by the french mathematician Jean Fourier. According to Fourier, even the most complex waveforms can be described by the sum of many simpler sine waves and cosine waves of appropriate phases and amplitudes. The results of modern research have confirmed Ohm's original idea that the auditory system performs a Fourier analysis of air-borne sounds by breaking them down into basis frequency components of different phases and amplitudes.

  Also, we want to reproduce a stereo sound stage, and arrival times at left and right ear are an important cue.  Tests have shown that the ear can differentiate very short differences in arrival time, and I have seen it suggested that recording at 192 kH is actually warrented to preserve these cues, even if we can't hear 96 kH sine waves. 

Jeff

To localize the position of a sound source, the auditory cortex utilizes the cues of interaural differences in the time of sound arrival (a few tenths of a millisecond) and interaural differences in sound intensity only, in spite of can have been suggested.


I think that the mechanism used by the ear to transform incoming sounds -the Fourier analysis- and the means by which complex sounds are received by the ear and interpreted by the brain are out of the scope of this forum.

Yours, Von (but not James Bond).

[d5]

Wow! Sanken has some really cool mics!! that stereo mic with the two card caps looks great.  +t for the link

just don't mount it upside down...

 

[Gutbucket]

To localize the position of a sound source, the auditory cortex utilizes the cues of interaural differences in the time of sound arrival (a few tenths of a millisecond) and interaural differences in sound intensity only, in spite of can have been suggested.

Time arrival and intensitly cues are the mechanisms most often used in stereo sound recording and reproduction, but they are not the only cues used by the auditory cortex.  There is a third mechanism as well: spectral modification of the signal due to the effect the outer ear has on signals arriving from various angles. 

This is why true binaural recordings work best when played back for the person who made the recording (using their own outer ears) and can fail to work so well for someone with a dramaticaly different ear shape.  The time of arrival and intensity cues are pretty much the same for different individuals.  Ear spacing, head size and shape (affecting time & intensity cues) vary much less than ear shape (effecting eq from differing angles).

This mechanism is used for true HRTF modeling done by NASA and other research labs.  It is very expensive to record the HRTF for a single individual across a full 3-d sphere and computationaly intensive to use the data to modify binaral reproduction, but has been done for fighter pilots and military air traffic controllers who need to keep spatial track of multiple sources of information while doing various tasks (really fast). HRTF data is available for the Kemar dummy head with various interchangable ears and labs have been working to try and find good average fits to general populations with differing ear shapes.

-rambling on a minor point. OK, back to work!