Role of Loudness in the Speaker's Judgment of Vocal Effort

Abstract

A previous paper noted a surprising difference between the exponent of the loudness function (0.6) and the exponent that describes the apparent growth of vocal effort (1.1). The fact that perceived loudness plays no more than a minor role in a speaker's judgment of his vocal effort is further demonstrated by these experimental findings: 1. The form and the exponent of the subjective scale for vocal effort remain relatively invariant under large changes in auditory feedback. When all auditory feedback was suppressed by an intense masking noise (110 db SPL), the exponent was about 1.3. (This larger value is partly an artifact caused by the speaker's tendency to raise his voice in an effort to override the masking.) When the “side tone” from the speaker's voice was amplified to a very high level, the exponent turned out to be approximately 0.9. 2. In order to show that the nature of the vocal sound (the phoneme ɑ) does not account for the results, listeners estimated the loudness of a live voice and of different levels of a recorded speech sample. For both types of sound the measured exponent was approximately 0.7. This compares with the exponent 1.1 obtained when the listener judges his own speaking level.