The importance and effect to and above 20kHz...


Hi Everyone -

I was wondering if anyone would care to elaborate on the importance of system frequency playback as the frequency range approaches and passes 20kHz. What effect does 15kHz have on music, for instance, and why is it important to keep the upper frequencies as linear as possible? How about 18kHz, or 20kHz, or 25kHz? What effect can these specific frequency regions have on the overall performance, and why should I keep them linear?

Let me clarify, I used those particular frequencies as examples, but if they can be expounded upon, then go ahead. I'm hoping everyone understands what I'm trying to get at. What effect can the upper treble frequencies have and why is linearity in these regions so important? Same goes for above 20kHz, say in the 22-30kHz region.

Can anyone explain?

Thanks for you help.
cdwallace

Showing 2 responses by shadorne

I am not aware of any evidence that frequencies beyond audibility (around 15 KHz for most of us) have any relevance at all. The basilar membrane is a band limited device and can't resonate enough above 20 KHz to generate any neural discharges to the brain.
For example, 20hkz and a 22khz interacting together would create a 2khz beat freq. Whether or not there is enough energy in this signal that could affect the hearing would be difficuilt to say

Good point. Not many people are aware that we can't even hear proper waveforms above 4 KHz....the ear's nerve bundles fire too slowly! In order to hear above 4 KHz the brain relies on two things; beat frequencies and differences in timing of what arrives at one ear versus the other.

However, very low signal amplitude because the basilar membrane does not vibrate enough to transfer energy to the inner ear at higher frequencies impies that you can't even hear beat frequencies for signals with frequency content higher than 20 Khz (or 15 Khz for most of the older folks).