Sampling rates higher than 44.1Khz? Options

[Grand Dizzy]

I recently met a musician who claims he can quite easily hear the difference between 44.1KHz and 96KHz.

This shocked me a little because I'd always been told that the human ear cannot hear any higher quality than CD (44.1KHz) quality.

So... was this guy just lying (or fooled by his senses), or was I being lied to when I was told the human ear cannot hear any higher quality than CD?

This post has been edited by Grand Dizzy: Feb 5 2006, 01:11

[Grand Dizzy]

This thread is fascinating! But most of it is too techy for me unfortunately.

Could anyone try again to explain how these byproduct tones/beats come about? And what is the low pass filter's involvement in this? (What is a low pass filter anyway?)

[ChiGung]

This thread is fascinating! But most of it is too techy for me unfortunately.
Could anyone try again to explain how these byproduct tones/beats come about? And what is the low pass filter's involvement in this? (What is a low pass filter anyway?)

Imagine two people walking side by side but with different length of steps. They can start pacing together on the same foot, but soon they will be out of step, and on different foots, some more steps later theyll get into pace again and some steps more -out of pace...the cycle will continue.
That cycle is the beating of the two different paces.
The PCM record is like noting down the gross foot position every click of a timer, so on clicks where both walkers feet are agreeing the gross foot position will be complimentry , when the walkers are directly out of step, each foot's position will counter the other and if directly out of step (and the feet are equal weight) their positions impression in the gross feet record will be zero.
In the record it looks like there is one foot moving at a similar rate but twice as much as each of the real feet, but coming in and out of existence in time with the beat period.

The question of how this beat period is generating an actual tone (other than the two tones related to the walkers paces) on playback of the record, is in contention in this thread.
Some believe that the beat period will be heard as a tone (walkers pace), or that the period will produced a tone in the air ~maybe a fluid dynamic phenomenon or something. It should be remembered that the beat isnt a tone though, its the periodic rising and falling in loudness of a tone.

The frequency of the tones being examined here is ultrasonic but playing their PCM record is producing an audible tone with the frequency of the beat period. This is suggesting to some people that beat periods are hearable as tones.
A lowpass filter cleans a pcm record of all mathematicaly apparent suggestions of sinusoidal oscillations above a certain frequency, (allows all the lower frequencies to pass).
When the ultrasonic test signal is lowpassed to remove theoreticaly inaudible frequencies from the record, the 'sound' of the beat frequency disappears as well.

The question is, is the 'sound' of the beat frequency something we would hear in real life or is it an error of the digital recording and playback process?

[LoKi128]

The question is, is the 'sound' of the beat frequency something we would hear in real life or is it an error of the digital recording and playback process?

The sound of the beat freq has nothing to do with the digital process. You could say it is a completly analog phenomenon. It will happen with a digital source as well as with some high-bandwidth analog tape or a vinyl deck or whatever. It is just the mix of two different signals.

[ChiGung]

The sound of the beat freq has nothing to do with the digital process. You could say it is a completly analog phenomenon. It will happen with a digital source as well as with some high-bandwidth analog tape or a vinyl deck or whatever. It is just the mix of two different signals.

I know a beat will happen whatever, but a sound is generated in some playback configurations and not others.

So you added two sine waves with an amplitude of -3dBFs? In that case the result will clip and that may explain the tone you heard..

No ones been listening to clipped test signals

It has been mentioned that in the real world very high frequencies like this may produce audible products, but with these test signals no post processing has been done to the sine waves to simulate possible real world phenomenon, the impression of two ultrasonic sines should be all that is present in the PCM record -no subtle air dynamic phenomon in this signal. But an unexplained noise is present on playback. Since, high quality lowpassing leaves no audible noise, it is consistent with the virtual sines not having generated any extra audible product.
So threre really appears to me to be a problem in the playback. Maybe this is lax internal resampling in the soundcard, or patterned rounding error, i can only guess.
Maybe try same experiment at 24 bits, or try playback through a ~XiFi