Perceptual audio coding is ubiquitous and perceptual audio codecs like MP3 and AAC are widely known. It has fundamentally revolutionized the way how we transmit, store and consume music, fueling applications like Internet streaming and downloading of music. Perceptual audio coding combines elements from digital signal processing, coding theory, and psychoacoustics into one system. It is, however, mostly the use of psychoacoustic noise shaping techniques that frequently leads to questions from non-experts (“Is this signal really intact?”) and sometimes is even perceived as some kind of “black magic” within the coder.
To educate users and listeners, the AES Technical Committee on Coding of Audio Signals (TC-CAS) has created educational material on “Perceptual Audio Codecs – What to Listen for”. It comprises tutorial information on the principles and limitations of perceptual audio coding technologies, as well as curated listening examples to educate and train listeners to identify possible audio coding artifacts.
Originally published as a CD-ROM in 2001, the material has been updated in content and functionality and been released as “The Second / Web Edition” for its 20th Anniversary in 2021. After the Web Edition has initially been exclusively available as an AES membership benefit, it is available free of charge to the general public since February 2023 for the 75th Anniversary of the AES, by courtesy of the AES and its Technical Committee on Coding of Audio Signals.
It is a useful resource for understanding the why’s and how’s of perceptual audio codecs, containing a taxonomy of common types of codec artifacts, as well as tutorial information on the background of each one. Example audio signals with different degrees of impairment illustrate the nature of the artifacts and help in training listener expertise. With this support, you can become your own expert listener in audio coding!
The research colloquium guides through this useful resource, with the speakers Jürgen Herre (TC chair) and Sascha Dick (editor).
Resources:
– Tutorial freely available at: https://aes2.org/resources/audio-topics/audio_coding/perceptual-audio-codecs/
– Promotional Video (YouTube): https://www.youtube.com/watch?v=QKBkBvV-HCw
– AES Paper: Dick: “Introducing the Free Web Edition of the ‘Perceptual Audio Coders – What To Listen For’ Educational Material”, 154th AES Convention, Helsinki, May 2023, Express Paper 87, https://www.aes.org/e-lib/browse.cfm?elib=22112
The new AES Germany Research Colloquium aims to provide a platform to discourse on a specific audio topic and create a bridge between basic research, manufacturers, and users in audio technology.
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More about AES Germany:
https://aesgermany.org/