Re: High-frequency hearing in humans

["Maher, Rob" <rmaher@xxxxxxxxxxxxxxx>]

Although the DSP portion of an oversampled system has precisely defined
performance characteristics, I remain highly skeptical that the
transducers and analog electronics available to most users have ever
been evaluated in any meaningful way outside the 20-22kHz bandwidth.  I
encourage everyone to be cautious about drawing cause and effect
conclusions for anecdotal reports.  It may well be that your colleague
is hearing something, but the "how" and "what" is not likely to be
revealed by introspection alone.

Rob

-----Original Message-----
From: AUDITORY - Research in Auditory Perception
[mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Kevin Austin
Sent: Thursday, February 03, 2011 9:09 PM
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: Re: High-frequency hearing in humans

There may be other kinds of anecdotal evidence that get lost in the
mists of time.

The "breaking twig" was mentioned. There is a difference in sound
between a twig being broken under the step of a 3 kg animal, and under
the step of a 43 kg animal, and I think this difference might be
represented in the >8kHz range.

Anecdotally, I know someone who can 'hear a difference' between a 96kHz
and 192kHz recording. He's not sure "what" the difference is, but he
hears it. [He's one of the few people whose hearing I really trust.]
This implies [somehow] that there are / were people who had this 'extra'
advantage of extremely wide frequency response.

A colleague of mine has been working on clicks in an electroacoustics
aural perception course. He discovered that a 48kHz sampling rate was
"too crude", and that working at 96kHz (or higher), the differences
between clicks over 8kHz were noticeable. This is not quite what
sampling theory seems to say. At 44.1kHz, a single sample click
represents 22kHz, and a two sample click represents 11kHz. How does one
represent a 16kHz click with a 44.1kHz sampling rate?

This can be done at 192kHz, and an 11kHz click sounds different from a
16kHz click. Transients from a dry twig snapping or other tiny [very
high] sounds, could have provided an ever so slight evolutionary
advantage, but carried out over 10,000 generations, even a very small
advantage can be important.

It is my understanding that the smallest angle of discrimination 'head
on' is something under 5 degrees. This would make for a very short
inter-aural delay. If this distance is taken as a wave length, what
frequency is being represented?

Kevin




On 2011, Feb 3, at 2:48 PM, Bernard Mont-Reynaud wrote:

> Good points Jose and Kevin; a few cm is the distance between the ears
> and it makes evolutionary sense to be able to resolve inter-aural
delays
> that are critical in source localization, separation and
identification.
> 
>> ...
>> 
>> On 2011, Feb 2, at 2:14 PM, Piotr Majdak wrote:
>> 
>> Dear list,
>> 
>> thank you all for the many responses. Below I try to sort and
summarize the
>> information:
>> 
>> Reasons why extended (>8 kHz) high-frequency hearing may be important
>> (besides sound localization!) :
>> 
>> 
>> Piotr Majdak wrote:
>> 
>> Dear list,
>> 
>> I'm looking for the reasons for the good high-frequency* hearing  in
humans.
>> 
>> The reasons I have until now are actually the obvious ones:
>> * Pinna localization cues
>> * Interaural level cues (ILD, they actually start to work from around
2 kHz)
>> 
>> What do you think: if there were no need for the ILD and pinna cues,
would
>> there be any other reasons?
>> 
>> Thanks,
>> 
>> Piotr
>> *) say, above 8 kHz
>> 
>> 
>> 
>> --
>> Piotr Majdak
>> Psychoacoustics and Experimental Audiology
>> Acoustics Research Institute
>> Austrian Academy of Sciences
>> Wohllebengasse 12-14, 1040 Vienna, Austria
>> Tel.: +43 1 51581-2511
>> Fax: +43 1 51581-2530
>> 
>>