Sample rate, why it it so fixed rate ?

[Jiewen Z]

Hi，
If we look at the sample rate for CDs, it is always 44.1KHZ, and we can see many other sample rate in this field like 32K, 48K,192K.

My question is(for CD as an example) why it is 44.1K but 44KHZ as 44K is also a pretty good enough rate to sample audio signal, what is the deep consideration behand this number？

silimarly, what is the consideration for 32K,48K,192K, etc.

[Simon]

First question: why is CD audio at 44.1kHz and not 44kHz (please note: kHz, not KHZ or K) ? The reason is historical and not important and dates back to the early days of digital audio and compatibility with video frame rates.

Second question: why are there so many other “standard” sampling rates? The main alternatives are 48kHz, 96kHz, 192kHz and (rarely) 384kHz. Each one is double the lower rate, which is convenient when converting between sampling rates (especially when downsampling).

You probably have a sound card built into your computer that will handle 44.1kHz and 48kHz. If you’ve got a more expensive model, it may also handle 96kHz. Only professional equipment (e.g. in recording studios) uses 192kHz and above.

None of this really matters for speech. 16kHz sounds OK, 48kHz sounds better, and there is little point going higher than that.

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