McGill Audio Quality Lab

Subjective evaluation of MP3 compression for different musical genres

Authors: Amandine Pras, Rachel Zimmerman, Daniel Levitin and Catherine Guastavino

Affiliation: McGill University, CIRMMT, Montreal, Quebec, Canada

Published: 127th AES Convention 2009, paper 7879


Abstract: Mp3 compression is commonly used to reduce the size of digital music files but introduces a number of potentially audible artifacts, especially at low bitrates. We investigated whether listeners prefer CD quality to mp3 files at various bitrates (96 kb/s to 320 kb/s), and whether this preference is affected by musical genre. Thirteen trained listeners completed an A/B comparison task judging CD quality and compressed files. Listeners significantly preferred CD quality to mp3 files up to 192 kb/s for all musical genres. In addition, we observed a significant effect of expertise (sound engineers vs. musicians) and musical genres (electric v.s acoustic music).


Documents: slides, paper



Sampling Rate Discrimination: 44.1 kHz vs. 88.1 kHz

Authors: Amandine Pras and Catherine Guastavino

Affiliation: McGill University, CIRMMT, Montreal, Quebec, Canada

Published: 128th AES Convention, paper 8101


Abstract: It is currently common practice for sound engineers to record digital music using high-resolution formats, and then down sample the files to 44.1kHz for commercial release. This study aims at investigating whether listeners can perceive differences between musical files recorded at 44.1kHz and 88.2kHz with the same analog chain and type of AD-converter. Sixteen expert listeners were asked to compare 3 versions (44.1kHz, 88.2kHz and the 88.2kHz version down-sampled to 44.1kHz) of 5 musical excerpts in a blind ABX task. Overall, participants were able to discriminate between files recorded at 88.2kHz and their 44.1kHz down-sampled version. Furthermore, for the orchestral excerpt, they were able to discriminate between files recorded at 88.2kHz and files recorded at 44.1kHz.


Documents: paper



Discrimination between Phonograph Playback Systems

Authors: Jason A. Hockman, David M. Weigl, Catherine Guastavino, and Ichiro Fujinaga

Affiliation: McGill University, CIRMMT, Montreal, Quebec, Canada

Published: 131th AES Convention 2011, paper 8547


Abstract: Digitization of phonograph records is an important step towards the preservation of our cultural history and heritage. The phonograph playback systems (PPS) required for this digitization process are comprised of several components in a variety of price ranges. We report on the results of two listening tests intended to ascertain the extent to which expert listeners can discriminate between PPS of different price ranges. These results are intended to determine the extent to which component selection affects the discrimination between PPS and to provide a set of guidelines for the purchase of PPS components for the digitization of phonograph record collections.


Documents: paper