32-Bit Float Recording and Why It Is Amazing

Portable digital audio recorders are essential tools for oral historians, filmmakers, journalists, folklorists, documentary and podcast producers, and sound designers, and when recording high-quality professional sounding audio, the capabilities of the recording equipment matter. Once affordable audio recorders had high quality preamps and recorded at 24-bit/96 kHz , I feel there was only incremental innovation going into the portable digital recorders.

But the exciting recent incorporation of 32-bit float recording is revolutionizing how we approach audio recording. Compared to older 16-bit or 24-bit systems, 32-bit float technology offers unparalleled quality, precision, and simplicity. This post explores why 32-bit float recording is a game-changer for recording interviews or conducting any kind of field recording.

Understanding Bit Depth in Audio Recording

To most appreciate the potential impact of 32-bit float recording, it helps first to understand sample rate and bit depth, the fundamental measurements of digital audio quality.

Sample Rate

In digital audio, the sample rate represents the number of samples per second used to represent a waveform. The greater the number of samples used per second, the higher the sample rate. Kilohertz (kHz) is used to measure the sample rate; CD quality utilizes 44.1kHz, or 44,100 samples per second, and studio quality audio typically utilizes 96 kHz or 96,000 samples per second.

Bit Depth

The bit-depth measurement of digital audio refers to the amount of data (bits) used to represent each sample. The higher the bit-depth setting, the greater the amplitude values used to store each sample and, thus, the greater the dynamic range of the recording: the difference between the quietest input levels and loudest signals that can be recorded and reproduced by a particular system.

Higher bit depth directly correlates with the overall resolution of recorded audio. Until recently, the highest bit-depth capability of a portable digital audio recorder topped out at 24-bit, which is incredibly high quality. 

• 16-bit audio: This is the standard for CDs, and it offers a wide dynamic range of approximately 96 dB. 
• 24-bit audio: This format is standard in professional audio studio settings and more contemporary portable recorders, and it extends the dynamic range to about 144 dB.

For the past few years, manufacturers Zoom, Tascam, and Sound Devices have released a new generation of portable audio recorders that use 32-bit float format. Unlike fixed-point bit depths (16 or 24), 32-bit float dynamically adjusts its range, offering the theoretical dynamic headroom of 1,500 dB.

Remember, a jet engine comes in at about 120 dB, and a gunshot, fireworks, or other extremely loud sounds are measured up to 140 dB. 32-bit float has a theoretical dynamic range simply because 1,500 dB exceeds all theoretical possibilities. So, how is 32-bit float advantageous for recording interviews or conducting field recordings and why should you use it? 

Preventing Clipping and Preserving Detail

One of the most frustrating challenges when recording dynamic sound, such as the spoken word during interviews, is the ever present potential of clipping. Clipping occurs when the input gain or sound levels exceed the peak maximum level the recorder can handle, which results in a loss of information, causing distortion. I have a post and a video tutorial on optimizing your interview recording levels and avoiding distortion when using 16-bit or 24-bit capable recorders. However, 32-bit recording potentially changes everything. 

Imagine pouring a Guinness or root beer into a pint glass with 16-bit or 24-bit systems; if you pour too much, the pint glass overflows, and you lose the excess drink. In audio terms, clipping will cause irreparable distortion to the recorded audio signal.

With 32-bit float recording, you have more db of dynamic range. Despite the rising foam, the 32-bit float pint glass magically expands to hold as much Guinness or root beer as you want to pour.

No matter how loud the speaker shouts or laughs, 32-bit float ensures plenty of headroom, and the recorder dynamically adjusts to capture every detail without distortion. This capability makes 32-bit float recording particularly valuable for interviews, where the volume of a speaker’s voice can fluctuate unexpectedly and sometimes dramatically. This is especially helpful for recording live music as well.

Similarly, when recording soft sounds like a whisper or a shy narrator or interviewee’s voice, 16-bit and 24-bit systems will struggle with background noise (the audio equivalent of graininess in a photo) when later boosting levels after the interview. In contrast, 32-bit float excels at capturing even the faintest details, ensuring the highest possible sound quality. 

It Becomes Much Harder to Fail

Conducting field recordings or interviews involves unpredictable conversations or performances and variable recording conditions. Maximizing the gain of your recording will often pose an increasing risk of clipping, which can sometimes feel like walking a tightrope.

On one hand, I feel like 32-bit float recording is like having a safety net beneath that tightrope, but more accurately, 32-bit float is like a safety harness that won’t even allow you to fall in the first place.

It eliminates the need for precise gain adjustments in the moment of recording, capturing the entirety of the dynamic range (including the highest levels) without distortion or noise. You could record with the gain levels set too high or too low, and the recording will still be perfectly salvageable during post-production. 

32-bit float technology ensures that all the nuances of the sound are recorded, allowing for comprehensive adjustments in post-production. For instance, the damage is permanent if an interviewee or narrator unexpectedly breaks out in loud laughter, exceeding the peak maximum levels of the recorder, causing distortion in a 16-bit or 24-bit recording.

With a 32-bit float file, you can lower the loud noise levels in your editing software to reveal pristine laughter without clipping, as if the moment had been recorded initially at the perfect level. This flexibility is particularly beneficial for oral historians, journalists, or podcast producers who often work in less-than-ideal environments and will not have the luxury of re-recording interviews.

For interviewers, this means eliminating the guesswork involved when setting initial gain levels prior to recording the interview and focusing on the conversation rather than constantly worrying about your recording levels.

The Downsides: The Need to Fix it in Post and File Sizes

32-bit float recording is not the same as automatic level control. Even though you may be using a recorder set to 32-bit float, you may still need intervention to create the perfect recording.

32-bit float recording means that following the end of your recording session, you can lower or raise your levels without consequences when you adjust your audio levels using digital audio software such as Adobe Audition, Audacity, Logic Pro X, or Pro Tools on your digital audio workstation (DAW), or if you are a filmmaker using Adobe Premiere Pro, DaVinci Resolve, or Apple’s Final Cut Pro.

If you needed to raise the gain on an initially quiet 16-bit recording, you would significantly increase the noise floor or introduce more noise. Since clipping is, theoretically, no longer possible with 32-bit recording, the most common intervention I am anticipating will be raising the levels of quieter recordings. 

Despite the assurances of 32-bit float recording, your recording quality will still greatly depend on the quality of your preamps and your microphone. See my post Microphones, Oral History, and that “Radio” Sound in the Field about Microphones, Oral History, and that “Radio” Sound in the Field.

Gain Knobs and Limiters

Personally, when I am working with audio equipment in the studio or out in the field, I like turning knobs. The higher-end 32-bit float recorders, such as the Sound Devices MixPre 3 II or the Mix Pre 6 II and the Tascam Portacapture X6 or the X8 indeed, still utilize traditional gain knobs for adjusting the levels in the field.

However, some 32-bit float recorders, such as the Zoom F3 or the Tascam FR-AV2, are designed for portability and simplicity and do not have a physical gain knob or dial. Additionally, some recorders remove limiters when recording in 32-bit, as the notion of infinite headroom eliminates the limiter’s raison d’etre.

Not being able to adjust the gain during the original interview assumes that if the levels are not ideal, it doesn’t matter; you can fix it in post-production later on the computer. Although the fix (to lower or raise audio levels) will not have the traditional consequence of increasing noise or risking distortion, you may still have to fix your audio in post to achieve optimal audio.

Suppose you could easily raise or lower the recording levels on the recorder using the gain knob during the interview, you save yourself the extra step of having to use the software later to optimize the recording levels of the audio file. Nevertheless, with 32-bit float recording, you could conduct a recording session without adjusting gain levels whatsoever. 

Fair warning: 32-bit audio files have a data footprint that is 33% larger than 24-bit files. Modern storage solutions (such as high-capacity SD and Micro SC cards), faster computer processors, and more robust digital audio software solutions make this concern (potentially) less significant. Transferring 32-bit float audio recordings from the original recording media to the computer will take longer in a real-world archival or production scenario.

Despite its advantages, if 32-bit float recording is not for you, the new recorders will allow you to change the recorder settings down to 24-bit, offering flexibility for different projects and specific needs. Recording in 16-bit is still pretty good for spoken word; Recording in 24-bit is still considered professional and in line with best practices. Some skeptics argue that 24-bit recordings will suffice to capture the dynamic range of 99% of use-case scenarios.

Call it technical determinism, but I assume that 32-bit float will supersede 16-bit and 24-bit recording. As audio technology advances, adopting 32-bit float recording will also ensure that you are ahead of the curve and your recordings remain compatible with future standards. Just as audio professionals transitioned from 16-bit to 24-bit, I am confident that 32-bit float will emerge as the new baseline for recording interviews and best practices. 

Conclusion

This past year, I have been recording using 32-bit float audio (recorded as uncompressed WAV files) for all of the interviews I am conducting and, for that matter, any field recording adventures I embark on. I have personally used the Sound Devices MixPre 3 II, the Tascam FR-AV2, the Tascam Portacapture X6, and Zoom F3 to record 32-bit float audio.

Indeed, there have been times when I recorded in 32-bit float and still had to load the audio file into Adobe Audition to make some mild changes to the audio levels, and the resulting audio quality has been incredible. I am old school, so I still really like turning gain knobs (thank you Sound Devices) and I also really still like the comfort and security (maybe it is just the perception of security) of having limiters on my digital audio recorders.

I firmly believe that the introduction of 32-bit float recording will be a transformational moment for portable audio recording and audio production. By eliminating the risks of clipping and additional noise, simplifying gain adjustments, and offering unparalleled flexibility in post-production, this technology empowers interviewers and field recordists to focus on their subjects rather than their equipment.

Whether you’re an oral historian preserving life stories, a journalist capturing the quote, the folklorist or ethnomusicologist recording a song or performance, or a podcaster producer recording stories for future broadcast, 32-bit float recording will make it much easier to ensure that every recording will be recorded to its full potential and that the entirety of your root beer float or Guinness beer, despite the rising foam, will remain in the pint glass and be fully enjoyed. 

Just to be clear, apart from the 32-bit float analogy, the proper Guinness pour is an art form that requires much practice. As for your root beer float, the overflow is part of the fun, so enjoy!