If you’re recording music with a digital recorder, you’ve probably come across the terms sample rate and bit depth. These are the two main factors that determine the level of detail in the sound. The sample rate determines the frequency range of your recording and the bit depth determines the dynamic range. Read on to find out which settings are the best to use for your productions.
Bit depth example in colors
Sample rate in bit-depth
Sample rate: audio pixels
You can compare the sampling frequency of a digital signal with the number of pixels in a digital photo. As with digital photos, digital sound is divided into very small parts. With photos, those pieces are called pixels and with sound samples. The sampling frequency is expressed in kilohertz (KHz). The standard sampling frequency for CD is, for example, 44.1 kHz. That means that every second of your recording consists of 44,100 samples. Unlike photos, you will not hear any “blocks” at very low sample rates. The sound becomes mainly muffled.
Why 44.1 kHz?
In the late 1970s, Sony and Philips decided to choose 44.1 KHz as the default sample rate for their digital audio devices. That number may seem random, but there is definitely an idea behind it. The sample rate must be at least twice the highest rate you want to capture. If the sample rate is lower, the converters may misinterpret the super high frequencies. This phenomenon is called “aliasing.” Since, in theory, the human ear can detect frequencies from 20 Hz to 20 kHz, the sampling frequency should be at least 40 kHz. The additional 4.1 kHz is intended as a kind of buffer for the low-pass filter that is used to prevent aliasing above 20 kHz.
Why higher than 44.1 kHz?
Audio interfaces and DAWs often offer the ability to record at much higher sample rates, sometimes up to 192 kHz. This has several advantages. For example, the low pass filter mentioned above can be set much more gradually. Also, with the extension of time and the change of pitch, the noise will disturb you less. Keep in mind that the higher the sample rate, the larger your audio files will be. Plug-ins also require a lot more computing power from your computer at higher sample rates.
Hit my parts
So the sample rate tells us how many pieces the recording is made of. But how many different pieces can we choose from? In other words: in how many steps do we go from the softest sample to the hardest sample? We determine this with the bit depth. With most DAW and audio interfaces, you can choose between 16-bit or 24-bit. If you make very smooth recordings at a low bit depth, you have the possibility that the softer passages will disappear in the noise and you may even get distortion.
99 problems but a little is not one
The standard bit depth for CDs is 16 bits, which gives us a dynamic range of 96 dB. That’s a considerable improvement compared to say tape (+/- 80 dB), but in the studio world, 24-bit is generally chosen. With the 144 dB that we have then in dynamic range, we hardly really have to worry about the noise that the digital medium adds to the signal. In fact, it’s better to record and mix a little too low than too high.
