When it comes to critical audio concepts, dithering is one that confuses many. It doesn't get the focus it deserves, but it can make or break the fidelity of an audio file render. Let's run down what dithering is, how it works, and why it's important in electronic music production.
What is Dithering?
Dithering in audio is when low level noise is intentionally applied to an audio file rendered at a lower bit depth. This addresses quantization distortion that’s introduced during the process. So…what does that mean?
When analog audio is recorded to a digital medium it’s sampled through analog-to-digital conversion (ADC). The bit depth determines how accurately the amplitude of the sound wave is represented. Ultimately, the bit depth determines the total number of potential amplitude values that can be accurately captured and represented—and when the incoming sound's amplitude doesn't align perfectly with those discrete values, it winds up being "snapped" to the closest value. This phenomenon is known as quantization. Sample rate determines how many times per second the converter measures amplitude level.
Higher bit depth and sample rate translates to better resolution and audio quality and more dynamic range. But when bit depth is reduced later in the process, it is quantized again. Some information is lost which leads to a phenomenon called a "quantization error." Because audio is typically recorded at 24-bit or 32-bit and later converted to 16-bit for CDs or streaming, accounting for quantization error is an important step in the process.
How Dithering Works
The issue with quantizing audio again when rendering is there are only a limited number of vertical steps to capture the waveform. Quantization in this case is the process of averaging the waveform to each nearest step. This inevitably happens when recording sound—converting a sound from its analog, continuous state to a digital format inherently requires this type of quantization.
The term dithering comes up most frequently when bouncing a song out of a DAW to a stereo file. When a DAW exports a file at a lower bit depth, it gets quantized again—but in this instance there are usually even fewer values to work with (because again, it's common to record at 24-bit or 32-bit and bounce down to 16-bit).
When this happens, the values of individual samples get rounded up or down. The lower the export bit depth, the more severe the rounding. This is what produces quantization errors and distortion. Dithering adds very subtle random noise variations throughout the audio, which reduces the auditory perception of the quantization error effects. Some are still present—they’re just not as audible.
Dithering is usually the final step in the mastering or track finalization process after all processing and production decisions are made. It should always be applied when reducing the bit depth of the output file and rendering to a lossless audio format like .WAV or .FLAC.
When and When Not to Dither
Deciding when and when not to apply dither depends on the situation. When you’re still working with an audio file in the mixing or mastering stage, you want to be working at the highest bit depth and sample rates possible—ideally, the settings in which the audio was captured.
Generally, you'll want to apply dithering when reducing bit depth. If you’re exporting a file at the same bit depth, dither is unnecessary. Likewise if you’re rendering to a lossy file like .MP3. They don’t have a bit depth and no amount of dithering will make them sound better! Happily, this process is generally part of your DAW's exporting workflow, and generally speaking, dithering options will be pre-selected unless you've opted for one reason or another not to apply dithering. The default assumption is usually that you do want to apply dithering.
When it comes to mastering, if you’re sending a mix file out to get professionally mastered, you can generally expect the mastering house to apply dithering since they are providing the final stereo file—but of course, you should contact them to make sure that your files are in line with their preferred workflows.
Electronic music production comes with its own set of rules. Dithering is still an important concept to understand considering the proliferation of home and project studios. This is especially true if you handle every production phase yourself and are new to the idea.
Dithering becomes a concern when you are rendering your audio files at a reduced bit depth. It does more harm than good if you’re bouncing to compressed formats like .MP3. Final masters in electronic music tend to be heavily compressed, and if you don’t apply dithering appropriately, quantization distortion errors might be even more noticeable.
Conclusion
Dithering is an important concept in the process of creating the best-sounding tracks. It uses noise to negate the quantization distortion error effects of bit depth reduction. It’s a vital step when rendering an audio file to a lower bit depth, but there are no positive effects when rendering to lossy files like .MP3 or .AAC.
This simple, often overlooked step is crucial in ensuring every track is ideally represented in its final output format.
Brandon Stoner is a lifelong musician and audio engineer who owns more guitars than anyone needs. As a lover of all things writing and music technology, he crafts every piece with his dog Max on his lap.