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Wide bandwidth = necessary?

Hi folks, there is one paradigm that bothers me a bit: many experts and audiophiles are stating that Red Book technology is outdated because of it's bandwidth limited function. I've read the human ear is capable of perception of frequencies beyond the normal human hearing, up to 40kHz. But this is only with live music! When listening to recorded music there is a restricted bandwidth because many microphones can only pick up frequencies up to 20kHz. So why the need for more and more bandwidth with regard to digital sound reproduction technology? What is not present in the recording can't be heard either, even with very wide bandwidth music reproduction gear.
What is also laughable is that many vinyl adepts say that phono playback gear can reproduce tones as high as 40kHz and that is one of the reasons phono playback sounds more "natural" than digital playback. This is a bit of a contradictio in terminis because most LP's are very band limited (30Hz to 16kHz is quite common). Your comments please.

Chris
dazzdax

Showing 3 responses by shadorne

shadorne's avatar
shadorne
7,477 posts
 
I've read the human ear is capable of perception of
frequencies beyond the normal human hearing, up to 40kHz.

Where have you read this? Was it in a reputable science journal or someone who
just bought a supertweeter?

The ear drum is filter - I don't think anything much above 20 Khz gets through.
shadorne's avatar
shadorne
7,477 posts
 
I found out that I could hear the introduction/removal of a low pass filter at a frequency well above the frequency at which I became stone-deaf to a sine wave (the usual test signal).

That is quite normal from many sharp low pass or brick wall filters which will introduce a ripple on what passes through - you can indeed hear the ripple. Essentially any box function applied to a signal will introduce ripple within the band. There are phase effects to. You don't have to resort to the idea that we can hear ultrasonics (like a bat) to believe that a filter can be audible.

Here is an example of a chebyshev filter
shadorne's avatar
shadorne
7,477 posts
 
Possibly, I don't know how high you are talking. For example, an analog filter with a low slope is going to have a large knee with an effect on frequencies over about a decade. (so a simple analog RC low pass filter with a 3db point way up there at 40KHz would still audibly attenuate frequencies down to about 8,000 Hz - it would be subtle though)
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