Temporal Relations in Pure-Tone Contralateral Masking

Abstract

Masking overshoot (increase in masking at either the transient onset or offset period) was measured at nine test frequencies surrounding a 1000-Hz, 50 dB SPL masker of 1000-msec duration. The brief maskees (5-msec duration at maximum amplitude) were presented near masker onset (initial position) at the midpoint of the masker (medial position) and near-masker offset (final position). Averaged across subjects and frequencies, onset overshoot was significant while offset overshoot was not. Onset overshoot occurred at all test frequencies and its magnitude was directly related to the magnitude of initial-position masking. The magnitude of onset overshoot was less than reported by Zwislocki et al. [Perception Psychophys. 2, 59–64 (1967) and J. Acoust. Soc. Amer. 43, 1257–1271 (1968)]. Offset overshoot appeared primarily at the lower frequencies but was not significant at any frequency. A follow-up study compared masking at the medial position with steady-state masking. The steady-state masker was more efficient than the medial-position masker at frequencies immediately surrounding the masker. [This study was supported by the Oklahoma City VA Hospital and was based on Lankford's dissertation completed at the University of Oklahoma Medical Center.]