Heyser Lecture - Louis Fielder

Presenter:
Louis Fielder, Retired - Millbrae, CA, USA

The Richard C. Heyser distinguished lecturer for the 147th AES Convention is Louis D. Fielder.

Psychoacoustics Applied to Dynamic-Range and Nonlinear-Distortion Assessment
The psychoacoustics of noise detection, measurements of noise in the digital-audio recording storage reproduction chain, and measurements of peak-acoustic pressures in music performances are combined to determine the requirements for noise-free reproduction of music. It is found that the required ratio between the maximum reproduction levels and the perceived audibility of noise can be as much as 124 decibels. When more practical circumstances are considered, this requirement is shown to drop to more feasible values. Next, the concept of auditory masking is introduced to allow for the assessment of nonlinear distortions in digital-audio conversion systems operating at low signal levels and then several examples of digital-audio conversion systems are examined. Finally, an expanded use of masking and a model to calculate a total nonlinear-distortion audibility number are used to determine the audibility of nonlinear distortions in headphones when driven by sine-wave signals at or below 500 Hz. Examples of headphone distortion assessment are examined and extension of this measurement technique to low-frequency loudspeaker evaluation is also discussed.