16-Bit vs 24-Bit vs 32-Bit Audio
Bit depth refers to the number of bits recorded for each sample in a digital audio file. It determines the possible dynamic range that can be represented in the audio. Higher bit depths allow for a greater dynamic range, resulting in higher audio quality and resolution.
The three most common bit depths for digital audio are 16-bit, 24-bit, and 32-bit. 16-bit is the standard bit depth used for CDs, MP3s and streaming audio. 24-bit is higher resolution and used in Blu-Ray, HD downloads, and some streaming services. 32-bit is the highest bit depth commonly available today.
The higher the bit depth, the more detailed and nuanced the audio can be. This article will examine the key differences between 16-bit, 24-bit and 32-bit audio in terms of dynamic range, file size, audibility, and use cases.
What is Bit Depth?
Bit depth refers to the number of bits used to represent the amplitude of a digital audio sample. It determines the range of values that can be used to represent the amplitude at each moment in time of an audio signal. With more bits, a wider range of amplitudes can be represented.
For example, 16-bit audio has a bit depth of 16 bits per sample. This means there are 2^16 (65,536) possible values to encode the amplitude at each moment in time. 24-bit audio uses 24 bits per sample, allowing for 2^24 (over 16 million) possible amplitude values. The greater bit depth allows for a more accurate reproduction of the original analog waveform when it was digitized.
A higher bit depth results in greater dynamic range, which is the difference between the loudest and softest sounds that can be represented. It allows subtle details and nuances in the audio to be captured instead of lost when digitized at a lower bit depth. This is why higher bit depths like 24-bit are favored for high fidelity recording and production.
16-Bit Audio
16-bit audio has a bit depth of 16 bits per sample and a dynamic range of 96dB. It has become the standard format for audio CDs and MP3 files. 16-bit audio is commonly used for music playback and distribution due to its reasonable audio quality and small file sizes.
The main benefits of 16-bit audio are:
- Small file sizes – About 10MB per minute of stereo audio.
- Compatible with most audio playback devices like CD players, smartphones, computers, etc.
- Sufficient dynamic range for most listening environments.
The main limitations are:
- Limited dynamic range compared to 24/32-bit formats which can capture more detail.
- Higher noise floor which can result in audible hiss in quiet sections.
- Less headroom for editing before clipping occurs.
While 16-bit audio is acceptable for most playback uses, the limited dynamic range means that some nuances in the original recording may be lost. For professional audio work where the finest details matter, 16-bit is less suitable compared to 24-bit or 32-bit.
24-Bit Audio
24-bit audio has a resolution of 24 bits per sample, giving it a dynamic range of 144 dB compared to 96 dB for 16-bit audio (Source). This greater bit depth allows 24-bit audio to capture a wider range of volumes and nuances than 16-bit.
24-bit audio is commonly used in music production and audio engineering. It provides more headroom for editing audio without introducing quantization noise or distortion. Many audio interfaces, digital audio workstations (DAWs), and recording devices now use 24-bit resolution.
The advantages of 24-bit audio include:
– Wider dynamic range
– Lower noise floor
– Greater precision in capturing and editing audio
– Less quantization distortion
The downsides are:
– Larger file sizes compared to 16-bit
– Playback requires compatible hardware/software
– Debatable whether benefits are audible in final output
While 24-bit audio is common in production workflows, the final distribution format is often 16-bit CD quality or compressed formats like MP3. However, some services like Tidal now offer 24-bit streaming for audiophiles. Overall, 24-bit audio provides more flexibility in recording and editing, even if the audible differences in final playback may be subtle. (Source)
32-Bit Audio
32-bit audio has a bit depth of 32 bits, allowing for an extremely wide dynamic range and virtually noise-free audio quality. With 32 bits, the theoretical dynamic range is 1,520dB, which is far beyond the human hearing range of 140dB (source: https://www.wired.com/story/32-bit-float-audio-explained/).
The primary advantage of 32-bit audio is its ability to capture an enormous dynamic range without noise or distortion. This makes it ideal for audio production and editing workflows where effects and volume adjustments are applied repeatedly. Having all that headroom prevents clipping or distortion. 32-bit float point encoding also avoids any quantization errors that can occur in fixed point bit depths.
However, for final distribution and playback, 32-bit audio is overkill. The human ear cannot perceive anything beyond 24-bit, and the large file sizes are not practical. 32-bit is also not well supported across consumer devices. So while recording and editing in 32-bit is beneficial, the audio should be converted to 16-bit or 24-bit for the end listener.
Audio Dynamic Range
Bit depth affects the dynamic range of the audio signal, which is the difference between the loudest and quietest sounds captured. With a higher bit depth, there is more resolution for capturing quiet sounds before they are drowned out by louder sounds. This results in a wider dynamic range.
Each additional bit doubles the number of possible values that can be used to represent the sampled audio waveform. For example, 16-bit audio has 65,536 possible values, while 24-bit audio has over 16 million values. Having more possible values provides more precision for capturing subtle details in the recording across a wider dynamic range.
According to Wikipedia, 16-bit audio has a theoretical maximum dynamic range of 96 decibels (dB), while 24-bit audio has a potential dynamic range of 144 dB [1]. This means that 24-bit audio can capture sounds 48 dB quieter than 16-bit audio before they are lost in the noise floor.
Higher bit depths allow for much quieter sounds to be reliably encoded and decoded during the digital recording process. This prevents loss of detail for very quiet sounds and allows a wider range of loudness to be represented in the final recording.
Audio File Size
Higher bit depth audio results in much larger file sizes. Each additional bit doubles the amount of data stored for each audio sample. For example, 16-bit audio stores 65,536 possible values per sample, while 24-bit audio stores over 16 million values per sample. This means that a 24-bit file will be 50% larger than the same length 16-bit file, and a 32-bit file will be 100% larger than the equivalent 16-bit file.
For an audio file of the same sampling rate and duration, the size difference can be calculated accurately by looking at the increase in bit depth. Doubling the bit depth doubles the data stored per sample, and therefore doubles the file size. Going from 16-bits to 24-bits is a 50% increase in file size, while going from 16-bits to 32-bits is a 100% increase in file size for that identical audio clip. So higher bit depths lead to much larger file sizes and storage requirements.
According to Wikipedia, “Examples of bit depth include Compact Disc Digital Audio, which uses 16 bits per sample, and DVD-Audio and Blu-ray Disc, which can support up to 24 bits per sample.” (https://en.wikipedia.org/wiki/Audio_bit_depth).
Audibility of Difference
Overview research on whether the differences between 16/24/32-bit audio are audible show mixed results. Some studies have found that in controlled tests, trained listeners can barely tell the difference between 16-bit and 24-bit audio (1). However, other research has shown that 24-bit audio provides a larger dynamic range and lower noise floor, allowing subtle details to emerge that may get lost in 16-bit audio (2). It seems the audibility of differences depends on the listening environment, audio equipment, and discerning ears of the listener. For most consumer use cases, 16-bit is likely sufficient, while 24-bit may provide advantages for audio engineers and discerning audiophiles.
(1) https://www.reddit.com/r/audiophile/comments/ahqn23/is_there_an_audible_difference_between_16bit_and/
(2) https://www.soundguys.com/audio-bit-depth-explained-23706/
Use Cases
16-bit audio is sufficient for most everyday listening situations like streaming music or playing video games. The additional dynamic range and reduced noise floor offered by 24-bit and 32-bit audio is generally not noticeable without specialized equipment in these scenarios.
However, the benefits of higher bit depth audio become more apparent in certain professional use cases like audio engineering, recording, and production. For example, according to MakeUseOf, 24-bit audio is recommended when editing and mixing audio in a studio setting. The increased headroom allows more flexibility and precision when processing audio signals.
Mastering engineers also often prefer working with 24-bit or 32-bit files over 16-bit. The greater bit depth preserves more detail when applying dynamics processing and avoids additional rounding errors and quantization noise that can accumulate during mastering. This results in a smoother, more natural sound.
Audio professionals working with a wide dynamic range also benefit from 32-bit float audio. With its immense headroom, 32-bit float can handle transient peaks over 120dB without clipping, making it very useful for field recordings and live music.
In summary, while 16-bit is fine for playback in most consumer use cases, professional audio workflows can gain an advantage from the benefits of 24-bit or 32-bit audio.
Conclusion
In summary, the key differences between 16-bit, 24-bit and 32-bit audio are the bit depth, dynamic range, and file size.
16-bit audio has a bit depth of 16 bits, a dynamic range of 96dB, and smaller file sizes. It is commonly used for CD audio and MP3 files. 24-bit audio has a bit depth of 24 bits, a dynamic range of 144dB, and larger file sizes. It is used for high-resolution audio like FLAC files. 32-bit audio has an extremely high bit depth of 32 bits but its practical dynamic range limit is around 144-150dB. File sizes are very large.
For most consumer use cases, 16-bit audio is sufficient. 24-bit audio provides higher quality for audiophiles, recording engineers, and other pro users. 32-bit audio is overkill for most purposes except certain niche professional applications.
The differences between 16-bit, 24-bit and 32-bit audio may not be detectable by casual listeners on consumer equipment. Discerning audiophiles with high-end systems are more likely to appreciate 24-bit over 16-bit. However, the benefits diminish as bit depth increases and are negligible beyond 24-bit for most practical uses.
The best recommendation is to use 16-bit audio for typical music listening, 24-bit for high quality and archival purposes, and 32-bit only for specific professional studio applications that require the highest dynamic range.
