We have over 12,000 students, from over 100 countries, within one of the safest campuses in the UK


93% of Lancaster students go into work or further study within six months of graduating

Home > Research > Publications & Outputs > The role of suppression in the upward spread of...
View graph of relations

« Back

The role of suppression in the upward spread of masking.

Research output: Contribution to journalJournal article


Journal publication date12/2005
JournalJournal of the Association for Research in Otolaryngology
Journal number4
Number of pages10
Original languageEnglish


The upward spread of masking refers to the higher growth rate of masking for maskers lower in frequency than the signal, compared to maskers at the signal frequency (Wegel RL, Lane CE. The auditory masking of one pure tone by another and its possible relation to the dynamics of the inner ear. Physics Rev. 23:266–285, 1924; Egan JP, Hake HW. On the masking pattern of a simple auditory stimulus. J. Acoust. Soc. Am. 22:622–630, 1950; Delgutte B. Physiological mechanisms of psychophysical masking: Observations from auditory-nerve fibres. J. Acoust. Soc. Am. 87:791–809, 1990a, Delgutte B. Two-tone rate suppression in auditory-nerve fibres: Dependence on suppressor frequency and level. Hear Res. 49:225–246, 1990b). The upward spread of simultaneous masking may arise from a combination of excitatory and suppressive effects. In this study, growth of masking functions were obtained for a 4-kHz signal masked by an on-frequency (4 kHz) or off-frequency (2.4 kHz), simultaneous or forward masker, in the presence of a notched noise with a center frequency of 4 kHz presented to restrict off-frequency listening. Compression was estimated from the slopes of the off-frequency growth of masking functions. Suppression was estimated by comparing the off-frequency simultaneous- and forward-masked growth of masking functions. Results showed that, for mid-level signals (35–60 dB SPL), the compression exponent estimated from simultaneous and forward masking averaged 0.31 and 0.26, respectively. The maximum amount of suppression (defined as the decrease in the basilar-membrane response to the signal) was variable, ranging from about 6 to 17 dB across subjects. Despite the substantial reduction in the response to the signal, the results suggest that suppression has a minimal effect on the slope of the masking function at mid levels. Rather, upward spread of masking seems to be mainly determined by the compressive basilar-membrane response to the signal in relation to the linear response to the lower-frequency masker.