Effects of signal frequency and ear of input on ICP-determined loudness adaptation

Abstract

The ipsilateral comparison paradigm (ICP) uses a monaurally presented base tone punctuated by referent tones of greater or less intensity to reveal magnitude-estimated loudness adaptation. Research with this technique has demonstrated adaptation across a broad spectrum of base-tone intensities [Dange etal., J. Gen. Psychol. 120, 217–274 (1993)]. Given evidence for different coding mechanisms at high and low signal frequencies and ear differences in adaptation [Ivry and Libby, Psychol. Sci. 4, 41–45 (1993); Davis and Weiler, Br. J. Audiol. 12, 59–60 (1978)], the present study examined the generality of ICP-determined loudness adaptation for the two ears at frequencies of 250, 1000, and 4000 Hz. Base tone intensity in all conditions was 50 dBA. Three referent conditions (+10 dB referent, −10 dB referent, and a no referent control) were also employed. The generality of ICP-determined adaptation was demonstrated by similar declines in loudness over time in all ear/frequency combinations when referent tones were present. Adaptation effects were noted for the base and for the referent tones. In addition, adaptation was stronger for the base tone in comparison to the +10 dB referent and for the −10 dB referent in comparison to the base, a result consistent with Hood’s model of loudness adaptation [Weiler and Hood, Audiology 16, 499–506 (1977)].