Perceptual Audio Coding

Music 422, Winter 2024

Instructor: Marina Bosi

Course Description

Did you ever wonder how your MP3 files squeeze so much sound into such a small size file? What the difference is between MP3 and AAC? Or which multichannel audio coding format is best for your application? The need for significant reduction in data rate for wide-band digital audio signal transmission and storage has led to the development of psychoacoustics-based data compression techniques. By using this approach we can exploit the limitations of human hearing to remove inaudible components of audio signals. The degree of bit rate reduction achievable without sacrificing perceived quality using these methods greatly exceeds that possible using lossless techniques alone. Perceptual audio coders are currently used in many applications including digital radio and television, digital sound on film, multimedia/internet audio, mobile devices.

This class integrates digital signal processing, psychoacoustics, rate/distortion optimization, and programming to provide the basis for understanding and building perceptual audio coding systems. We review the basic principles underlying all the core components of a perceptual audio codec and study the design choices applied in state-of-the-art audio coding schemes, e.g., AC-3 (Dolby Digital), Enhanced AC-3, AC-4; MPEG Layers I, II, and III (MP3); MPEG AAC; and MPEG-H. In-class demonstrations will allow students to hear the quality of state-of-the-art implementations at varying data rates and, as a final project, you will program your own simple perceptual audio coder.


The Winter 2024 schedule, subject to updates, is available on CANVAS. Required readings from the course textbook:

M. Bosi & R.E. Goldberg, "Introduction to Digital Audio Coding and Standards", Springer, 2003, ISBN: 978-1-4020-7357-1.

are referenced for each week. As a general rule, readings should be always done according to topics and prior to class. Unless otherwise specified the class will meet at CCRMA (map) on Friday afternoons from 2:30 PM until 4:20 PM.

To ensure a safe, diverse and inclusive environment, we cultivate discussions that are respectful of gender, sexuality, disability, age, socioeconomic status, ethnicity, race, and culture. We support students from all backgrounds whose diverse perspectives bring a tremendous asset to the class. It is important that there be an atmosphere of trust in the classroom, and our priority is to provide a safe and inclusive learning environment where students' contributions are encouraged and valued.

Students with a disability that may necessitate an academic accommodation or the use of auxiliary aids and services in class must initiate the request with the Student Disability Resource Center (SDRC). Please contact the SDRC as soon as possible; timely notice is needed to arrange for appropriate accommodations. 

TA: Emily Kuo



To earn 3 units in this course you will have to come to class, participate, do the homework exercises, and complete a final project. This is the final grade breakdown:

  • 45% homework
  • 45% project
  • 10% classroom participation

We aim to promote a culture of personal integrity and academic honesty through our interactions and we follow the Honor Code . While the students may have group discussions about the homework assignments, the homework submissions are expected to be written up individually and to be representing the students' own work.

Office Hours

Marina Bosi

  • Friday: 4:30 - 5:30 pm (Knoll 217, Classroom)
Emily Kuo

  • Monday: 5:30 - 6:30 pm (Knoll 217, Classroom)
  • Thursday: 5:30 - 6:30 pm (Knoll 217, Classroom)



The main course website is accessed through Canvas, Stanford University's learning management system. All homework assignments, grades, and supplementary materials are accessible via the Canvas site, and all homework submissions must take place via your Canvas assignment submission portal. More details about homework presentation and submission, late homework policy, and final project can be found here .

Music 422 Canvas Site »


Please do not hesitate to contact Marina Bosi or Emily Kuo with any questions or concerns.