Comment by Joeboy
14 years ago
> Digitally recording a triangle is the best example of why 48kHz is very limiting
The article's about distribution, not recording. I don't think anybody disputes the usefulness of higher sampling rates when recording.
> In theory, it's true that the human hear can't hear above ~18kHz, but it can hear the influence of the very high pitch harmonics on a lower frequency.
...and 48kHz audio contains those lower frequencies.
Stripping frequencies above 20kHz negates the effect on the lower frequencies since those lower frequencies are not "modified" by the higher ones. The human hear can actually hear the very high harmonics when they're combined with a lower fundamental frequency.
For example, the human hear will hear a 30kHz frequency if it's fundamental is 10kHz. If it's played at 44.1kHz, the 30kHz frequency is gone and all you'll hear is 10kHz, not a "different sounding" 10kHz.
For example, the human hear will hear a 30kHz frequency if it's fundamental is 10kHz
You are going to have to provide me with a citation to back that up because that goes against everything I've learned and experience in 17 years of working in acoustics.
Here is a Wikipedia article on the subject: http://en.wikipedia.org/wiki/Sound_from_ultrasound
Basically, if you produce two ultrasonic frequencies, they will create an interference pattern at a much lower frequency than either of the individual frequencies. Modulate a signal on the difference between two signals, and you can create a directional speaker, since ultrasonic sounds tend to be highly directional (so long as the diameter of the transducer is greater than 1/2 wavelength, which is almost guaranteed with ultrasonic signals). This is how the "sound cannons" that are being deployed for crowd control work.
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It's definitely possible for two sounds to be indistinguishable when played separately, but when played together it is revealed that they are in fact different (see link below). Whether this applies for sounds with frequencies above 20kHz I don't know. I'd like to see a citation as well. Doesn't seem like it would be the hardest experiment to set up either.
http://en.wikipedia.org/wiki/Cent_(music)#Sound_files
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Humans will hear the impact > 20kHz frequency has on the lower frequencies, not the 30kHz frequency itself. That's been proven a million times.
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Are they talking about "beat frequency" type effects?
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> For example, the human hear will hear a 30kHz frequency if it's fundamental is 10kHz.
No. It won't.
I think you're referring to this: http://en.wikipedia.org/wiki/Missing_fundamental
Which, since it's a psychoacoustic phenomenon, wouldn't hold true when the partials involved are above the audible spectrum.
I know where you're going with this I think, and I'm not disagreeing outright, but wouldn't this be captured during the high-bitrate (or good analog?) recording and mixing phase if the recording/mixing/mastering engineer were doing things right? At least, as well as possible?
> The article's about distribution, not recording. I don't think anybody disputes the usefulness of higher sampling rates when recording.
Didn't read the article, so commenting out of context, however it needs to be said that in sample-based music genres the distributed music gets used as if it were a recording. Maybe then it could be argued that higher sampling/bit rates should be available, if only for those who are sampling.