There seem to be a lot of different sample rates in digital audio. I would like to know how to choose which sample rate to record at.
The sampling rate of digital audio must be at least twice the highest audio frequency you want to record.
So because the highest generally accepted audio frequency is 20 kHz (20,000 Hz), the lowest feasible sampling rate would be 40 kHz.
In fact, because of the filters that have to be used to prevent a nasty effect known as aliasing, there has to be an additional 'safety margin'.
So in the early days of digital audio, two sampling rates became common - 44.1 kHz and 48 kHz.
44.1 kHz was chosen because it worked well for the early digital recorders that were made using adapted video recorders.
48 kHz was also common because it was easy to convert to the 32 kHz rate that was commonly used in telecommunications.
Eventually 44.1 kHz became the standard for CD; 48 kHz became the standard for anything to do with video.
These days, it is easy to convert from 44.1 to 48, and vice versa, with almost no quality loss, so it doesn't matter that much which rate you choose. In theory 48 kHz ought to be capable of a slightly better frequency response, but it is only a small difference that is extremely hard to hear.
As technology developed, it became possible to handle and record audio at a sampling rate of 96 kHz. 88.2 kHz is also possible, but the nice round number of 96 kHz seems to have won that particular battle.
96 kHz is a huge advance providing two benefits...
- High frequency response can be improved
- Filtering can be more gentle, which is a good thing
There are occasions however where it is possible to record at 96 kHz, but not necessarily desirable.
One key area is multitrack recording using a DAW.
Recordings made using 96 kHz require twice as much processing than recordings made at the lower rates.
It follows then that the computer will have to work a lot harder to process high sample rate audio.
This results in a lower track count and fewer plug-ins before your computer runs out of steam.
For many recordists, a 96 kHz sample rate imposes too many restrictions, so they choose to record at a lower rate.
In time this will change, as computers get faster and more powerful. Eventually there will be no reason to record at anything less than 96 kHz.
For now it is worth bearing in mind however that very few people can actually hear the difference between 96 kHz and 44.1 or 48. The sampling rate you choose is very unlikely to have an effect on the marketability of your work.
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