My name is Dylan, I’m an engineer at New Alliance East, and I’ll be writing a series of posts about working with audio. Some of these will read a bit like a textbook/glossary entry or of the “tips and tricks” sort, and will mostly be written from the viewpoint of a mastering or mixing engineer.
Eventually I plan to include anecdotal posts about interesting scenarios and the hardware/software that made things work.
The first term I’d like to discuss is Sample Rate. A “sample” of sound is the sonic equivalent of a video frame. In other words, it’s the smallest discrete section of a piece of audio. The number of those samples contained within the span of a second is determined by the sample rate. For CDs, with a standard sample rate of 44.1kHz, each sample is “1/44,100th” of a second.
That number isn’t random, it’s derived from the Nyquist Sampling theorem. Put simply, the theorem states that since sound is an oscillation between two amplitudes, to accurately represent that sound you must have at least two samples per oscillation. In other words, one sample for each amplitude.
There are other standards when it comes to different mediums from CD. In film, 48kHz is used instead of 44.1kHz. When recording an orchestra, some engineers like to record at as high as a 192kHz sample rate, because the harmonics created by instruments, such as those in an orchestra, go much higher than 22hz, and they interact with lower frequencies we can hear.
In a more empirical context, sample rate is also the medium through which all interfaces sync together. If your interfaces are set to different clock speeds, or sample rates, or they are different from your project’s internal sample rate, you will run into various problems.
Playback can sound too fast or too slow, bit-crushed, downsampled, otherwise digitally distorted, or even just refuse to play.
You generally want to keep track of what sample rate all your bounces/exports/projects/etc are running at, so you don’t end up taking more time troubleshooting a sample rate issue than actually getting some art done. Additionally, in this day and age, with computers as powerful as they are, only work in 44.1 if you’re forced to for some reason. Even 48k is a big step up in quality.
In conclusion, this is a relatively basic audio term, but a thorough understanding can help prevent some nasty hiccups along the way.