Physics + Math

28
Feb

Physicists Discover Why MP3s Sound Worse

Chris Lee, writing for Ars Technica:

Modern audio compression algorithms rely on observations about auditory perceptions. For instance, we know that a low-frequency tone can render a higher tone inaudible. This perception is used to save space by removing the tones we expect will be inaudible. But our expectations are complicated by the physics of waves and our models of how human audio perception works.

This problem has been highlighted in a recent Physical Review Letter, in which researchers demonstrated the vast majority of humans can perceive certain aspects of sound far more accurately than allowed by a simple reading of the laws of physics. Given that many encoding algorithms start their compression with operations based on that simple physical understanding, the researchers believe it may be time to revisit audio compression.

It’s because, they say, humans perceive sound nonlinearly. Lee does a nice job explaining why that causes current compression algorithms to fall short.