Audiometric tones are deliberately aperiodic so subjects cannot anticipate them

Evidence

The spring-loaded output key is used to present the sound, thereby giving the operator control of when the sound is being presented and removing any pattern of presentation that might allow the subject to predict when to expect the next sound. Such unpredictability adds to the overall power of the test, but in the context of hearing measurement, it is particularly important when hearing is being tested in the context of, at one extreme, a legal claim for damages being made for hearing loss due to noise-induced hearing loss or, at the other, a health screening for normal hearing as part of a job interview. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 2343

Categorization

• XREF: Parallels the psychoacoustic method of randomizing stimuli to defeat expectancy effects, a recurring theme in the book’s earlier chapters.