Effect of level on spectral-ripple detection threshold for listeners with normal hearing and hearing loss

This study investigated the effect of presentation level on spectral-ripple detection for listeners with and without sensorineural hearing loss (SNHL). Participants were 25 listeners with normal hearing and 25 listeners with SNHL. Spectral-ripple detection thresholds (SRDTs) were estimated at three spectral densities (0.5, 2, and 4 ripples per octave, RPO) and three to four sensation levels (SLs) (10, 20, 40, and, when possible, 60 dB SL). Each participant was also tested at 90 dB sound pressure level (SPL). Results indicate that level affected SRDTs. However, the effect of level depended on ripple density and hearing status. For all listeners and all RPO conditions, SRDTs improved from 10 to 40 dB SL. In the 2- and 4-RPO conditions, SRDTs became poorer from the 40 dB SL to the 90 dB SPL condition. The results suggest that audibility likely controls spectral-ripple detection at low SLs for all ripple densities, whereas spectral resolution likely controls spectral-ripple detection at high SLs and ripple densities. For optimal ripple detection across all listeners, clinicians and researchers should use a SL of 40 dB SL. To avoid absolute-level confounds, a presentation level of 80 dB SPL can also be used.