Bit depth ultimately determines a characteristic in recording called dynamic range. In short dynamic range is the distance between the loudest and quietest sound that can end up in your final recording.
Low bit depths can result in low quality, incomplete or even static-sounding recordings. It’s important to use a bit depth that will capture everything in your recording.
So let’s start by understanding the role bit depth plays in the recording process, then we’ll discuss how that can affect the quality of the recording file that you end up with.
Recap of Bit Depth
I’ve explained bit depth in detail in another article, but let’s quickly run through it again.
In home recording, we go through a multiple step process of turning normal sound waves (in the air) into a file saved on our computer. Here are the most important steps in that process:
- A sound is produced, which creates sound waves in the air
- Those sound waves are funneled into a recording device (usually a microphone)
- The recording device turns the sound waves into an electrical signal
- Another device (usually an audio interface) measures the electrical signal at various points in time
- Those measurements are transferred into computer language (1’s and 0’s)
- A long list of the measurements are saved in an audio file
Obviously, we glossed over some of the details, but we don’t need all those details in order to fully understand how bit depth and audio recording quality are related.
Steps 4 and 5 (where bit depth matters)
The only part of the process where bit depth matters is when the electrical signal from the microphone is being converted to computer language.
As the electrical signal flows into the audio interface, the interface will take samples, or snapshots of the electrical signal.
These samples are taken in very quick succession, and the speed with which they are taken is determined by the sample rate (often 44,100 samples per second).
These samples are recorded as 1’s and 0’s, where each 1 or 0 is called a bit.
Each sample is recorded as a specified number of bits, and the number of bits is equal to the bit depth.
So if your bit depth is set to 8, for example, then each sample will have 8 bits. An 8 bit sample might look like any one of these values:
- 01101001
- 10010010
- 00011100
- 11011100
Or any other combination of eight 1’s and 0’s. These samples represent (more or less) the strength of the electrical signal at a point in time.
And if the bit depth is 4, then those sample values will only have four 1’s and 0’s, like this:
- 1010
- 1100
- 0111
- 0001
Obviously, 8 bits has far more combinations and thus can contain more information than 4 bits.
How Bit Depth Affects Recording Accuracy
Now that we’ve revisited the crash course, let’s talk about how bit depth influences the final recording that we hear.
The two things we need to connect are:
- A sample measures the strength/amplitude of the electrical signal at a point in time
- Bit depth influences how accurately we can record that measurement
Basically, a higher bit depths means more bits in each sample, which means a more accurate reading.
Let’s look at an example to better understand what’s happening here:
A bit depth analogy/example
Note: This analogy is imperfect. It doesn’t perfectly equate to audio recording, but it does help us understand what’s happening during the recording process.
Let’s imagine that we have 100 humans lined up in a really long line. It’s our job to walk past each of them and measure how tall they are.
We’re asked to do this twice.
The first time we are given a measure that only has meters labeled. We are asked to take a measurement in meters.
As we walk past each person, we are essentially writing down one of two values (1 meter or 2 meters). Obviously there are more than two heights in this line of 100 people, so these measurements are very inaccurate.
The second time we are given a measure with centimeters labeled. We are asked to take a measurement in centimeters.
This time we write down many values ranging between 110 centimeters and 200 centimeters. These measurements are significantly more accurate.
This is much like how bit depth works. Low bit depths are like trying to measure in meters and higher bit depths are like trying to measure in centimeters.
How Bit Depth Affects Sound Quality
OK, we get it. Higher bit depths mean more accurate, more precise measurements of the electrical signal.
But how does this actually affect the recording quality?
Bit depth determines dynamic range
As I mentioned earlier, these are the two items that we need to understand together:
- A sample measures the strength/amplitude of the electrical signal at a point in time
- Bit depth influences how accurately we can record that measurement
We understand the 2nd item now. But let’s apply this understanding to the 1st item.
The sample measures the amplitude of the electrical signal.
So bit depth determines how accurately we can measure the amplitude of the electrical signal.
And the amplitude of the electrical signal is a representation of how loud the original sound was.
This is the key connection.
Dynamic range is a term that describes how many different sound intensities are available in a recording. Higher bit depths result in recordings with larger dynamic ranges and vice versa.
What is dynamic range?
Dynamic range is the distance, in decibels, between the loudest sound and quietest sound that we are able to record.
| Bit Depth | Dynamic Range |
| 4 | 24 dB |
| 8 | 48 dB |
| 16 | 96 dB |
| 24 | 144 dB |
| 32 | 192 dB |
Recording with a bit depth of 4 bits results in a dynamic range of only 24 decibels.
In practice, this means that the recording can only pick up sounds that fall within a certain intensity range. And that range is only 24 decibels wide.
For reference, normal conversation is about 60 decibels and loud singing is about 90 decibels. That’s already larger than the 24 decibel range.
So recording at a bit depth of 4 will not be able to capture a lot of the sound that should be recorded.
Higher bit depths allow dynamic recording ranges significantly higher than this.
What Bit Depth Should I Record At?
It is normally recommended that you record with a bit depth of either 16 or 24.
Mainstream music distribution saves music with a bit depth of 16 and thus playing the music back only allows for a dynamic range in accordance with a 16 bit depth.
However, when editing and mixing your recordings, it can often offer you more flexibility and control if your recordings have been done with a bit depth of 24.
Either of these two values will be sufficient in the vast majority of scenarios.
But one small thing to keep in mind is that higher bit depths use up more storage space, and can put a greater load on your computer (and audio interface) during the recording.
Most computers can handle higher bit depths, but if you ever find your computer slowing down/freezing during recordings, you can always try lowering bit depth (or sample rate) and see if the problem resolves itself.
Conclusion
Bit depth determines the dynamic range of a recording. If your bit depth is too low, then your recording can have static (at worst) or simply miss some loud or quiet parts of the original sound being recorded.
If you want best results in your home recording sessions, it’s best to use a bit depth of 16 or 24.
