Jan 28, 2004

For various reasons, both personal and professional, I’ve been doing quite a bit of reading for the past few weeks.

Some interesting items:

• John Atkinson’s “Measuring Loudspeakers” series (Parts 1, 2, and 3): lots of good information about obtaining and interpreting objective loudspeaker measurement data. The articles also touch on objective qualities that translate into positive or negative subjective responses, as well as loudspeaker design goals.
• Dave Moulton’s AES presentation on Acoustical Considerations for Loudspeaker Playback of Music in Small Rooms: this presentation gives some interesting perspectives on the difficulties of obtaining good sound in typical rooms. As a measurement guy, I particularly liked the discussion of accuracy (or lack thereof) in typical music recordings.
• MP3-tech.org has a great set of links to technical papers on various aspects to low-bit rate audio and perceptual coding. I also recommend reading the DTS whitepaper on their “Coherent Acoustics Coding System” used in the professional and home implementations of the DTS audio system. The MP3-tech.org site also has a link to some less detailed papers on Dolby’s perceptual coding system.

There was some discussion during the December BAS meeting about Dolby’s perceptual coding algorithms, and the subject of forward and backward masking came up. Some BAS’ers weren’t familiar with forward/backward masking (as opposed to simultaneous masking which should be familiar to most audio people).

To help people understand this type of masking, I scanned some pages from Brian Moore’s An Introduction to the Psychology of Hearing for that discuss forward and backward masking. Feel free to have a look (1.2 MB PDF).

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