The term “audio artifact” is probably something you’ve come across if you’re a music producer. Either in your own recordings or other peoples recordings.
This post will discuss what audio artifacts are and how they arise in relation to audio production.
With that said, What are Audio Artifacts?
In audio, sound or music production an audio artifact is an unwanted sound or noise such as hum, buzz and electronic noises that may be picked up during recording, from the recording process itself and from editing and processing.
Audio artifacts can sometimes be temporal and spectral and other times they can be occlusion which is accidental (like when somebody accidentally blocks the microphone while recording).
Sometimes audio artifacts can be used intentionally in audio production to achieve a desired goal but for the most part they occur unintentionally which could cause problems for audio engineers.
Therefore having a deep understanding into this topic will help have better context about this subject.
With that said let’s get into how audio artifacts can occur in audio and what they may be caused by.
Sources of Audio Artifacts
Sometimes, in the process of gain reduction, compressors can likely cause audible artifacts. In such a situation this can alter the timbre of sound thereby creating something unwanted. In other situations it may be intentional and may be done to contribute to the overall meaning of the sound recording.
The fact is that, with the use of a compressor to control dynamic range, you may run into audio artifacts being generated in your audio. Therefore the engineer has to be careful in ensuring that the peaks are well controlled to avoid the overall flow of sound from being disrupted. This takes some good ear training because some of the artifacts that may be created can be very difficult to actually hear.
Clicks are another type of audio artifact, they are basically short duration transient sounds that contain significant high-frequency energy.
They may occur and originate from malfunctioning equipment. This could be from the act of connecting and disconnecting analog signals from a patch bay or from digital synchronization errors in interconnection.
Clicks that result from malfunctioning equipment are usually random, making it difficult to find their exact source. In such a situation, a meter can be very helpful to indicate which audio channel contains the click.
When it comes to clicks that result from digital connections from equipment with digital connections between, it is important to ensure that sampling rates are identical across all interconnected equipment and that clock sources are pretty much consistent.
Without properly selected clock sources in digital audio, clicks are almost inevitable and will likely occur at some regular interval, usually spaced by several seconds.
Clicks that originate from improper clock sources are often pretty much subtle, and they require a good ear to identify them naturally.
Depending on the digital interconnections in a studio, the clock source for each device needs to be either internal, digital input, or world clock.
Pops are another type of artifact, they are basically transient sounds that have a thump-like sound.
They are usually a result of plosives that are consonant sounds. Pronouncing the letters p, b, and d, in which a burst of air is produced during the creation of the sounds.
A burst of air resulting from the production of a plosive arriving at a microphone capsule produces a low-frequency, thump-like sound.
Usually engineers will try to counter pops during the process of vocal recording by placing a pop filter in front of a vocal microphone.
Pop filters are usually made of thin fabric stretched across a circular frame.
Pops are not something heard from a singer when listening acoustically in the same space as the singer. The pop artifact is purely a result of a microphone close to a vocalist’s mouth, responding to a burst of air.
Pops can easily distract listeners from a vocal performance because they are not expecting to hear a low-frequency thump from a singer.
Usually engineers can filter out a pop with a high-pass filter inserted only during the brief moment while a pop is sounding.
Hum and Buzz
When analog circuits are not grounded properly as well as signal chains they can cause noise in the form of hum or buzz in analog audio signals.
Both are related to the frequency of electrical alternating current (AC) power sources, which is referred to as mains frequency in some places.
The frequency of a power source can either be 50Hz or 60Hz depending on geographic location and the power source being used.
Power distribution in North America is 60Hz, in Europe it is 50Hz, in Japan it will be either 50 or 60Hz depending on the specific location within the country, in most other countries it is 50Hz.
When there a ground problem present, a hum or buzz will be generated with a frequency equal to the AC frequency with added harmonics above the fundamental.
Hum and buzz are another type of audio artifact that you’ll run into in audio production.
Distortion can be used intentionally but it can also result unintentionally. It is also another type of audio artifact.
Whether or not distortion is intentional, an engineer should be able to identify its presence and either shape it for artistic effect or remove it, according to what is appropriate for a given recording.
With any form of recording there always exist technical restrictions in the way sounds can be captured, sonic errors will usually occur.
These terms are what we refer to as Audio Artifacts in audio engineering and production. They aren’t pleasing to the human ear which is why most audio engineers will use a variety of techniques to root them out and eliminate them altogether.
A sonic artifact can sometimes be a digital artifact and in other times can result from data compression.
A simple definition of data compression is that it is the process of encoding information using fewer bits than the original representation.
Other times audio artifacts are deliberately produced to sort of alter the timbre of the original audio to either create context or perpetuate a stylistic motive.
For example, A well known intentional way in which audio artifacts may be created are by overdriving an electric guitar or bass.
Other times sonic artifacts can also be intentionally added by introducing clicks and pops into audio. The obvious example in this scenario would be introducing vinyl crackle to create a sort of vintage feel.