Exploring Bit Depth: How It Shapes Digital Audio Quality

Mar 28

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Bit depth determines the richness and detail of the audio you hear. But exactly what is bit depth, and why is it crucial for audio quality?


In simple terms, bit depth refers to the number of bits used to represent each audio sample, a factor that defines how accurately a sound can be captured and reproduced digitally. This guide provides a straightforward look at bit depth, explaining how it affects sound quality and influences your audio experience in both professional setups and everyday listening.

Key Takeaways

  • Bit depth is crucial in defining the precision of digital audio samples, with higher bit depths providing greater dynamic range and lower noise floor, enhancing audio quality.

  • Increased bit depth results in larger audio file sizes and requires a balance between sound fidelity, storage requirements, and processing capabilities, particularly in professional audio production environments.

  • While higher bit depths can offer improved audio resolution and dynamics, the actual perceivable difference to the human ear in typical listening conditions may be negligible, making 16-bit audio suitable for most scenarios.


Unveiling Bit Depth in Digital Audio

Illustration of digital audio waveforms and dynamic range

Bit depth in digital audio is a concept that often gets overlooked, yet it’s a significant determinant of sound quality.

In the realm of digital audio, bit depth refers to the number of bits in each sample, marking the resolution of each sample and defining the precision of amplitude values. It’s the magic behind how those 0s and 1s transform into the music that floods your ears.

Long story short: the audio resolution, represented by the unique values a sample can hold, significantly increases with bit depth. Imagine having 65,536 unique values at 16 bits, then seeing it exponentially rise to a staggering 16,777,216 at 24 bits. This corresponding increase in dynamic range, from 96 dB to 144 dB, is a testament to how bit depth shapes the integrity and finesse of sound reproduction.


Wanna know more? Let’s delve deeper and explore the essence of bits in sound reproduction.

The Essence of Bits in Sound Reproduction and Sound Quality

In the world of digital audio, a bit is a binary digit that can hold one of two values: 1 or 0. It’s like a tiny container, a minuscule vault of information about the amplitude values of sound waves. This treasure trove of bits is what digital audio uses to reproduce sound waves, capturing more subtle fluctuations in the waveform as bit depth increases.

But how does bit depth affect the number of possible amplitude values?


It’s a matter of math. The number of possible amplitude values can be calculated using 2 raised to the power of the bit depth (2^n). That’s a lot of potential for variation and precision, which leads us to our next point: how bit depth determines dynamic range.

in a  digital signal more bit equal to a wider dynamic range

Bit Depth Determines Dynamic Range

Bit depth in digital audio is like a painter’s palette.

The more bits, the more colors you can paint with, or in this case, the broader the dynamic range. The dynamic range represents the difference between the loudest and quietest sounds that can be recorded or reproduced. Just as a painter can create more nuanced and detailed art with more colors, an audio engineer can record and reproduce more detailed sound with a higher bit depth.

The Dynamic range in both analog audio and digital audio. In a Digital Converter, Higher Capacity means a higher dynamic range

In theory, a 16-bit digital audio system provides a dynamic range of about 96 dB, while a 24-bit system can achieve a maximum dynamic range as high as 144 dB. However, real-world constraints typically restrict the maximum to around 120 dB in 24-bit audio interfaces due to limitations in converter technology.


Higher bit depths are essential in professional audio production, providing greater accuracy and headroom, which reduces the risk of clipping and noise in recordings.

But how does bit depth influence the digital noise floor?

The noise introduced by electronics components during the signal processing

Bit Depth and the Digital Noise Floor

The digital noise floor is the backdrop against which all sounds in a digital audio recording are set.

It’s the amplitude of the noise floor that determines the bottom of the possible dynamic range in digital audio. Think of it as the canvas on which the sounds are painted. The smoother and cleaner the canvas, the clearer and more vivid the painted sounds will be.

Higher bit depths reduce the noise floor, just as using a high-quality canvas reduces imperfections. This allows for a greater dynamic range in digital audio recordings.

An enhanced signal-to-noise ratio is crucial for achieving precise, noise-free audio, especially important for quieter recordings or detailed post-processing.

In analog and digital music, quiet sounds may suffer much more of the noise floor rather than higer level sounds

However, the human ear may not notice the difference between 16-bit and higher bit depths in typical listening conditions, as the noise floor of 16-bit audio is already very low.

Now, let’s examine the relationship between the number of bits (or capacity), the audio file size, and quality.

Bit Depth's Impact on Audio File Size and Quality

Illustration of different audio file formats, quantization noise and sampling frequency.

A higher audio bit depth doesn’t just mean a closer approximation to the original analog waveform; it also means larger file sizes.

Just as a higher-resolution image requires more storage space, so too does higher-resolution audio. An increase in bit depth results in a higher bitrate, which in turn means larger file sizes, especially for uncompressed audio files that contain the most data.

However, the world of digital audio is not confined to one format. Different digital formats and streaming services use varied bit depths. For instance, CDs have a consistent bitrate of 1,411 Kbps, while MP3s and streaming services like Spotify offer a range with lower average bitrates. But how does one balance file size with sound fidelity?

Learn why sample rate determines how many samples per second are taken

Balancing File Size with Sound Fidelity

When it comes to music production, deciding on the optimal bit depth involves a delicate balancing act.

You need to consider the desired quality, the file size you can manage, and the processing power you have available. Just as a filmmaker has to balance image quality with the demands of storage and processing, so too does an audio engineer have to balance audio resolution with the demands of file storage.


For instance, choosing a higher resolution like 192 kHz over 96 kHz would double the amount of hard-drive space needed. As with most things in life, achieving optimal audio quality involves trade-offs, in this case between audio resolution and file storage requirements. Moreover, professional audio equipment and software must support the high processing power and increased storage space demands associated with higher bit depths.

Speaking of professional audio production, how do high bit depths play out in professional recording equipment? Let's understand something more...

Audio sample and background noise in a pcm signal sound data depending on bit and file size

High Bit Depths in Professional Recording Equipment

In the realm of professional audio production, quality is king.


To achieve maximum audio quality and a broad dynamic range, a high bit depth such as 24-bit or 32-bit is recommended. High-end digital audio converters, commonly found in professional recording equipment, offer dynamic ranges up to 120 dB with 24-bit audio, which is at the upper end of industry standards (with the exception of some 32-bit sound cards)

Despite the theoretical maximum of 144 dB for 24-bit audio and 192 dB for 32-bit, real-world constraints typically restrict the maximum to around 130 dB due to sensor and microphone limitations. Yet, higher bit depths in audio interfaces provide increased headroom and a buffer against distortion, particularly valuable during the mixing and editing stages of the production process


OK! Now that we’ve explored the role of bit depth in audio production, let’s consider how our ears perceive bit depth.


The Human Ear and Bit Depth Perception

Illustration of human ear and sound perception

The magic of digital audio lies not just in the technology but in how our ears perceive it.

The bit depth of an audio recording determines the range of amplitude values that can be captured for each sample, ultimately influencing the resolution and quality of the audio. A higher bit depth allows for more precise audio signal representation. Higher bit depths increase the signal-to-noise ratio (SNR), allowing for louder recordings before noise becomes obvious.

What we perceive as higher resolution audio can provide a clearer and more detailed sound. Yet, perception is a tricky thing. Experienced engineers might distinguish differences between sample rates, but this becomes more challenging with technological advancements in digital audio. Moreover, for the final bounce of a project, a 16-bit system is often sufficient, as the difference between 65,536 (16-bit) and 4,294,967,296 (32-bit) amplitude levels is indistinguishable due to a very low noise floor.

Now the question is: can we actually hear frequencies affected by bit depth?

Can We Hear Frequencies Affected by Bit Depth?

Our ears are fine-tuned instruments, capable of detecting a wide range of frequencies. But how does bit depth influence what we hear? Noise shaping is a technique that can reduce the auditory perception of noise by moving it away from the mid-range frequencies, where human hearing has the highest sensitivity. It’s like a sound engineer tweaking the equalizer to make the music sound just right.


By employing a perceptual filter within a noise shaping system, the noise within the critical mid-range frequencies can be lowered. This has the effect of reducing the perceived noise floor for the listener. It’s a subtle art, shaping the noise to enhance the music. But is a higher audio bit depth always noticeable?

Is Higher Audio Bit Depth Always Noticeable?

In typical listening environments, the noise floor introduced by digital recording and playback equipment or the environment itself often limits the dynamic range of audio rather than the digital format’s bit depth. It’s like trying to appreciate a painting in a poor lighting room; the subtleties of the artwork are lost amidst the shadows.

For most music production scenarios, using a 48 kHz sample rate and an adequate audio interface delivers high-quality audio samples, which calls into question the noticeable benefits of increasing bit depth. It seems then that the true value of higher bit depths lies in the realm of professional audio production rather than casual listening.

But what happens when things don’t quite go as planned? Let’s explore the concept of quantization error and its effect on audio signals.

Quantization Error and Its Effect on Audio Signals

Illustration of quantization error in digital audio signals

Even in the precise world of digital audio, errors can occur.


One such error is quantization error, which refers to the discrepancy between the original analog signal and the nearest available digital value that represents it after sampling. It’s as if you’re trying to squeeze a round peg into a square hole; it might fit, but it’s not a perfect match.

This error manifests as noise, specifically as a digital noise floor, which is a type of low-level white noise inherent to digital audio. At each level of bit depth, the least significant bit is rounded to either 0 or 1, influencing the precision of the digital representation and affecting the quantization error.

But what does this error signal look like in digital systems?

An error that may occur in the digital realm

Understanding the Error Signal in Digital Systems

Quantization error arises due to the requirement of representing analog signals with a finite number of bits during the analog to digital conversion process.


It’s like trying to describe a sunset with a limited vocabulary; you can get the basic idea across, but some of the subtleties and nuances may be lost. This error manifests as noise, specifically as a digital noise floor, a type of low-level white noise inherent to digital audio.

The signal-to-noise ratio (SNR), which measures the ratio of the desired signal’s level over the level of this background noise, is affected by quantization error.


For every additional bit
added to the bit depth in a digital audio system, the signal-to-noise ratio improves by approximately 6 dB.


But can we mitigate this error and improve the signal quality?
The answer is YES!
We Can.


Some expert ears can even notice that in modern music. Do you know how many bits your music library has? Do you have high resolution audio?

Dithering - Mitigating Quantization Noise through Technology

Imagine you’re painting a picture, but you can only use whole numbers of paint drops.

Dithering is a technique that randomizes the rounding of the last bit during quantization, preventing patterns in the quantization error and introducing more randomized ‘uncorrelated noise’. It’s like adding half a drop of paint to achieve the perfect shade.

The introduced white noise from dithering helps to:

  • randomize the distortion spectrum caused by quantization error, reducing the perception of harmonic distortion

  • improve the overall signal quality when combined with noise shaping

  • subjectively improve audio resolution equivalent to an increase of two to three bits

  • produce cost-effective digital audio hardware without compromising, and in some cases improving, performance and audio quality



Ok, let’s now consider bit depth across different digital realms.

Bit Depth Considerations Across Different Digital Realms

Illustration of different digital audio realms

The world of digital audio isn’t confined to the recording studio or the concert hall. It permeates our everyday lives, from the music we stream on our phones to the sound effects in our favorite video games. To better understand this world, it’s essential to learn about digital audio basics. Different digital realms have different bit depth considerations, from the 16-bit audio used by most streaming services to the higher bit depths used by high-fidelity services and professional equipment. By exploring the digital sound wave, we can gain a deeper understanding of the intricacies of digital audio.

Archival audio, which seeks to preserve the fidelity of recordings over time, typically uses sample rates of 96 kHz or 192 kHz and may require higher bit depths. But how does one choose the right sample rate and bit for their needs?

Choosing the Right Bit Depth for Your Needs

Choosing the right bit depth is like choosing the right tool for the job. For home listening environments, 16-bit audio is often sufficient, offering a dynamic range that can exceed the ambient noise level in most cases. But for professional recording and critical listening, 24-bit audio offers a greater dynamic range and lower noise floor, increasing sound quality and flexibility in editing.


Audiophiles and virtual instrument users may prefer 24-bit audio to capture subtle nuances in the music and to achieve a more realistic and responsive instrument feel. However, it’s important to not only consider audio quality but also ensure compatibility with playback hardware and accessibility across different devices.


Now, what about the rate and bit depth in the age of streaming?

Bit Depth in the Age of Streaming

As technology advances, streaming services may trend towards offering higher bit depths. Currently, most streaming services deliver audio in 16-bit format, while some high-fidelity services offer 24-bit audio streams to cater to audiophiles. High-resolution audio is commonly considered to be 24-bit, 96 kHz, although this definition is likely to evolve with future technological advances.


There’s an ongoing debate about whether most listeners can distinguish between 16-bit and 24-bit audio on streaming platforms, which may be influenced by environmental noise. As technology continues to improve, a trend towards offering higher bit depths such as 24-bit could become more prevalent among streaming services.

However, to fully appreciate the quality of streaming audio, especially in higher resolutions, listeners must use high-quality equipment.

Summary

Digital audio is a fascinating realm and bit depth is a key factor that shapes it.


From determining the dynamic range to influencing file size and quality, bit depth plays a crucial role. It affects not only the quality of audio production but also our perception of sound. We’ve explored how bit depth works in digital audio, its impact on file size and quality, how our ears perceive it, and how it varies across different digital realms.

The world of digital audio is complex, but understanding concepts such as bit depth can deepen our appreciation for the music and sounds that enrich our lives. So the next time you listen to your favorite song or watch a movie, remember the role of bit depth in shaping your audio experience.

Frequently Asked Questions

Is 16-bit or 24-bit audio better?

For better recording, mixing, and mastering in the digital domain, 24-bit audio is significantly better than 16-bit due to having more to work with during processing and when doing destructive tasks.

What is a good bit depth?

A bit depth of 16 bits is suitable for consumer applications, while 24 bits is better for professional use like recording, mixing, and mastering. Choose the bit depth based on your specific use case.

What does 32-bit depth mean?

A 32-bit depth indicates that each audio sample is represented by 32 bits. This affords a more expansive dynamic range during the digital-to-analog conversion process, ensuring a more faithful preservation of the sound's dynamic range compared to lower bit depths.

What is bit depth 8 vs 12?

The distinction between 8-bit and 12-bit bit depths is found in the granularity of the digital-to-analog conversion process. An 8-bit system can differentiate among 256 distinct levels, whereas a 12-bit system can discern 4,096 levels. Classic samplers like the Akai S900, which are 12-bit, remain highly regarded for their drum sample texture even in contemporary music production.

How does bit depth affect file size and quality?

Higher bit depth increases file size and enhances audio quality by providing higher resolution and bitrate. This is particularly noticeable in uncompressed audio files.

About the Author

Max Porcelli

Steinberg Certified Trainer, DJ, and Producer with 29 years of experience. He owns 989 Records, an Electronic Music Label based in Italy. Every Saturday he hosts an exciting Radio Show called 989 Records Radio Show on air on Patchouli Deep Radio, London. 
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