Re: High-frequency hearing in humans

[Kevin Austin <kevin.austin@xxxxxxxxxxxx>]

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
>> 
>>