Although jitter is an important step in mastering the production process, knowing how to use it, when to use it and why to use it can improve your recording and final audio file.

1. What is jitter?

Jitter is low volume noise, which will introduce digital audio when switching from high level to low level.

The process of reducing bit depth will lead to quantization error, also known as truncation distortion, which will sound very unpleasant if it is not prevented.

In order to understand this better, we must understand the bit depth.

2. What is bit depth?

In the field of digital audio, bit depth defines the number of measurements used to describe the amplitude of a single audio sample. Each significant bit represents a dynamic range of 6db.

For example, the dynamic range of recorded audio made in 24 bits is 144db. (See the figure below 1-2).

Figure 1

Figure 2

3. Truncation distortion

For example, when you reduce the bit depth from 24 bits to 16 bits, you are reducing the number of values available for measurement, that is, the amplitude of any given sample. In other words, you can now use fewer values to describe the dynamic range of audio.

(See Figure 3-4 below)

Figure 3

Figure 4

Therefore, some values that no longer exist will be forced to round to the next closest value.

This truncation leads to a loss of very low signal level and produces auditory distortion when the value is rounded, which makes the waveform correct. (See Figure 5-6 below)

This is a 16-bit audio file with a line drawn in the middle, indicating the position of the audio before it is converted from 24 bits. (Figure 5)

This illustrates truncation distortion, in which audio is forced to bend to the nearest bit. (Figure 6)

4. How can jitter prevent this?

If you apply jitter to a muted audio file and turn up the volume, you can hear it alone.

If you add EQ at the end, even if there is no audio in the speaker, you will see the noise moving around, and you can even see this intuitively.

Introducing this subtle noise into the audio file before reducing the bit depth can eliminate truncation distortion, which is actually dealing with noise distortion.

Based on this information, one can determine that it is ineffective to use jitter on 24-bit audio and derive it at a bit depth of 24 bits or more, because nothing is replaced by noise, which is only needed when down-converting to a lower bit depth.

5. Computer screen metaphor

To better understand jitter, I use your computer monitor as an analogy. How to understand this? First, put your hand on the computer monitor.

Please note that you can see the computer monitor perfectly except the part covered by your hand.

Now, if you quickly wave your hand back and forth from left to right on the screen (simulating jitter), you can see the whole screen, including the part covered by your hand.

6. Why are you shaking?

Now that you have a better understanding of what jitter is, you may ask yourself, why jitter? "If you can keep 24-bit audio files, you can completely avoid jitter.

The answer is simple, because many audio files are 16 bits. Although 24-bit has higher quality and more audio details, which completely eliminates truncation distortion, in fact, 90% of the playback devices are 44 100/ 16 bits.

This means that if you try to play a 24-bit audio file through one of the 16-bit playback devices, it will sound very uncomfortable.

In this regard, you should keep the bit depth consistent throughout the production process.

If you use 24-bit production and the playback setting is 16-bit, then you should use the jitter tool in the production process.

If you record and make with 16 bits, and the playback is set to 16 bits, there is no need for jitter.

If you make it with 16 bits and the playback is set to 24 bits, there is no need for jitter.

What are your current settings? What is the current bit depth of your audio file? What is the bit depth setting of your playback device? These are all things to know when making tracks.

Note: If you intend to control your songs, it is best to set the project settings to the same or higher bit depth when exporting. For example, if you make it with 16 bits, make sure to export it with 16 bits or higher.

If your project setting is 24 bits, and you output with 16 bits without jitter, your audio file will be damaged before entering the master production.

7. Types and shaping options of dithering algorithm

Many perturbation options provide noise shaping. Noise shaping allows you to add an equalization curve to jitter noise, which helps to move the noise energy to areas in the spectrum that are not easy to hear, thus achieving better results.

Here are some common types of jitter. (I will use the jitter option of Ableton, but it is a very similar option in all programs) (see Figure 7 below).

Figure 7

● Triangle ULA: By default, the triangle is selected. If other processing can be performed on the file, this is the safest mode.

● Rectangular: Rectangular mode introduces less jitter noise, but at the cost of additional quantization error.

●Pow-r 1-3 (three Pow-r modes): Three Pow-r modes provide continuously higher jitter, but the noise is beyond the audible range.

8. Image analogy

Image dithering works in exactly the same way as audio dithering. Here are four pictures.

From left to right, the first one is an 8-bit image with full resolution, the second one is the same image reduced to 1 bit without jitter, the third one is a 1 bit image with jitter, and the last one is a 1 bit image with jitter and noise shaping options. (See Figure 8 below).

Figure 8

9. Conclusion and conclusion

Note that dithering is a process that is applied only once to any given audio sample. If you plan to further process the rendered audio samples, you'd better render them to 32 bits to avoid jitter at this stage.

Finally, you just want to render the audio jitter before playing. If it is sent to others for mastery, or it is not mastered, then don't shake it.

As to which mode is the best, it's best to spend some time studying the results with your ears.