Audio bit depth refers to the number of amplitude levels an analog-to-digital converter measures when capturing each sample of an audio signal.
This definition may be confusing if you’re new to audio production.
We’ll explain everything you need to know to understand bit depth in the following paragraphs.
Understanding audio bit depth is essential – it significantly impacts the quality of your final product.
In this post, we’ll explore bit depth in more detail, from how it works and why it matters in digital audio production.
What is Audio Bit Depth?
Bit Depth Analogy
Let’s start with an analogy that’ll help you understand audio bit depth.
Imagine you’re a painter.
Now imagine you have a paint palette with many colors on it.
The more colors on your paint palette, the more detailed and nuanced you can make your painting.
In contrast, painting with a limited number of colors can make your painting look flat and uninteresting.
This painting analogy relates to the effect that bit depth has on audio quality.
Bit Depth and Audio Recording
Take singing into a microphone for example.
We refer to the sound entering a microphone (your voice) as a sound wave.
Microphones convert sound waves into analog audio signals.
An audio interface receives audio signals and creates digital representations that a computer can understand.
By sampling or taking “snapshots” of the audio signal at certain intervals.
The sampling rate determines the number of snapshots or samples an audio interface takes per second.
The bit depth determines the amount of information it captures in each sample.
As mentioned before, an audio interface – more specifically its analog-to-digital converter (ADC) – uses these samples to recreate a digital version of an audio signal.
The digital audio signal consists of binary values (1s and 0s) that computers can use to process and store digital audio for recording, mixing, and playback.
What is a Bit?
A bit is the smallest unit of data in a computer’s system.
A higher bit depths allow an ADC to use a greater number of bits to represent each sample.
Using more bits helps the converter produce a more accurate representation of the original audio signal.
To go back to our analogy, a higher bit depth gives your ADC more colors to paint with.
Having more colors – or in this case a higher bit depth – allows your interface to reproduce a more detailed version of your voice or instrument in digital form.
How Bit Depth Works
Pulse Code Modulation and Quantization
As mentioned before, in the recording process we typically use an audio interface to convert audio signals into digital data.
An audio interface has an analog-to-digital converter (ADC) that does this job through a process called Pulse Code Modulation (PCM).
An ADC measures an audio signal’s amplitude, or loudness, at different points.
Then, it assigns a numerical value to these amplitude measurements, which is known as quantization.
What your computer receives is a numerical representation of an analog audio signal. This representation is what we refer to as a digital audio signal.
Your computer processes and stores digital signals as data, allowing you to record and manipulate them in your DAW.
Bit Depth and Amplitude Measurements
The bit depth determines the maximum number of possible amplitude levels that an interface can represent in each digital audio sample.
For example, a bit depth of 16 means that there are 2^16 or 65,536 possible amplitude levels your system can represent in each sample.
Similarly, a 24-bit bit depth represents 2^24 or 16,777,216 possible amplitude levels.
Since bit depth is a measurement of amplitude levels, it’s directly related to dynamic range.
Bit Depth and Dynamic Range: How Do They Relate?
Dynamic range is the ratio between the loudest and softest sounds an audio device can record and playback.
A higher bit depth means your audio interface can capture more amplitude levels per sample.
Therefore, a device with a higher bit depth will have a wider dynamic range.
How Does a Higher Bit Depth and Wider Dynamic Range Improve Audio Quality
With a wider dynamic range, you’ll be able to record louder signals without distortion. Plus, your recordings will have less noise (lower noise floor).
A wider dynamic range provides more distance between an audio device’s noise floor and the maximum recording level.
Therefore, your audio interface will be able to capture quieter sounds more clearly, and louder ones with less clipping or distortion.
In other words, a broader dynamic range allows your system to capture and reproduce cleaner audio signals.
It also provides more flexibility in the post-processing stage.
You can boost the volume of a quiet section in your recording without introducing as much noise as you would with a lower bit depth.
Likewise, you’re less likely to add distortion when enhancing louder sections.
Bit Depth Conversion and Quantization Errors
In PCM, quantization is the process of converting a continuous range of amplitude measurements into a set of discrete digital values.
The bit depth determines the number of possible digital values your interface uses to measure the amplitude at each point.
Quantization errors tend to occur when you reduce the sample rate and bit depth of a digital audio file – also known as downsampling.
For instance, downsampling from 24 bits to 16 bits reduces the number of values your interface can use to quantify the amplitude of an audio signal at a given point.
When converting to a lower bit depth, your system quantizes (or rounds off) the amplitude measurement at a given point to the nearest binary value (1 or 0).
The difference between the actual value and the quantized value is what causes quantization errors.
Quantization errors introduce a small amount of white noise (or background noise) into digital audio signals.
We refer to this noise as quantization noise.
You can use a technique called dithering during the mastering stage to reduce quantization noise
Audio engineers tend to use this technique when converting audio from a high-resolution format to a lower-resolution one.
Dithering consists of adding a small amount of random noise to a digital audio signal.
While this method sounds counterintuitive, it makes quantization noise less noticeable by spreading it over a wider range of frequencies.
You can dither your audio through a mastering plugin like Izotope’s Ozone.
Bit Depths Comparison: 16-bit or 24-bit?
At 24 bits, there are 16,777,216 possible amplitude values that your ADC can measure compared to 65,536 at 16-bit.
In other words, 24-bits provides a greater range of possible amplitude values for each audio signal, resulting in a more accurate and detailed representation of the original analog audio source.
As mentioned before, 24-bits also offers a wider dynamic range.
With a wider dynamic range, you’ll have more room to work with between the loudest peaks of your audio and the point where your audio starts distorting.
In audio production, we describe having more space between the loudest undistorted level and the maximum level that your system can handle as having more headroom.
Additional headroom allows you to add more effects in post-production without distorting your audio as easily as you would with less headroom.
Additionally, 24-bit recordings have a lower noise floor.
Therefore, background noise at 24-bits will be less noticeable even when recording quieter sound sources.
While a 24-bit recording uses more space on your hard drive, it enhances your audio resolution and widens dynamic range.
Is There a Noticeable Difference Between 24 and 32-Bit Audio
No, most people agree that there isn’t a noticeable difference between 24 and 32-bit audio.
In theory, a 24-bit audio file can represent 16,777,216 different amplitude levels, while a 32-bit file can represent 4,294,967,296.
Therefore, 32-bit audio has a greater dynamic range and can capture more nuanced and subtle variations in sound than a 24-bit audio file.
However, this difference is inaudible to the human ear.
24-bits offers plenty of headroom and a wide enough dynamic range for most recording situations.
Takeaway: What Is Bit Depth? Does a Higher Bit Depth Mean Better Quality?
To summarize, bit depth is similar to the number of colors a painter has in his paint set.
A painter with more colors in his paint set can create a more detailed and accurate picture.
Likewise, a digital audio file with a higher bit depth will more accurately reflect the original sound source.
Think of 24-bits as having more shades of color to choose from.
Conversely, 8-bits gives you a few basic colors.
The bit depth determines the total number times of an ADC can possibly measure the amplitude of an audio signal.
The higher the bit depth, the more amplitude levels can be represented – allowing for a wider dynamic range.
24-bits is considered the best bit depth to record at because it offers a wider dynamic range, more headroom, and a lower noise floor than 16-bits.
As a result, you’ll capture cleaner recordings and have more wiggle room for mixing and mastering before your audio starts to sound distorted.