Effect of multiple speechlike maskers on binaural speech recognition in normal and impaired hearing

Abstract

Speech-reception thresholds (SRT) were measured for 17 normal-hearing and 17 hearing-impaired listeners in conditions simulating free-field situations with between one and six interfering talkers. The stimuli, speech and noise with identical long-term average spectra, were recorded with a KEMAR manikin in an anechoic room and presented to the subjects through headphones. The noise was modulated using the envelope fluctuations of the speech. Several conditions were simulated with the speaker always in front of the listener and the maskers either also in front, or positioned in a symmetrical or asymmetrical configuration around the listener. Results show that the hearing impaired have significantly poorer performance than the normal hearing in all conditions. The mean SRT differences between the groups range from 4.2-10 dB. It appears that the modulations in the masker act as an important cue for the normal-hearing listeners, who experience up to 5-dB release from masking, while being hardly beneficial for the hearing impaired listeners. The gain occurring when maskers are moved from the frontal position to positions around the listener varies from 1.5 to 8 dB for the normal hearing, and from 1 to 6.5 dB for the hearing impaired. It depends strongly on the number of maskers and their positions, but less on hearing impairment. The difference between the SRTs for binaural and best-ear listening (the "cocktail party effect") is approximately 3 dB in all conditions for both the normal-hearing and the hearing-impaired listeners.

Real-time lexical competitions during speech-in-speech comprehension

“…When only a few talkers are present in the babble, masking effects may actually be more easily overcome because of clear acoustical distinctions between voices (Brungart, 2001) or because listeners can rely on asynchronies in the dynamic variations of the concurrent streams that cause transient gaps in the babble during which they can listen to target signals (Hoen et al, 2007). With an increasing number of talkers however, the dynamic modulations from the additive sources are progressively averaged, thus decreasing the temporal gaps free for listening to target words (Bronkhorst and Plomp, 1992;Drullman and Bronkhorst, 2000). This phenomenon has been considered as informational masking occurring at the acoustic-phonetic level (Hoen et al, 2007).…”

Congenital and Prolonged Adult-Onset Deafness Cause Distinct Degradations in Neural ITD Coding with Bilateral Cochlear Implants

“…Current benefits in sound localization are based primarily on interaural level difference (ILD) cues (van Hoesel 2004;Seeber and Fastl 2008;Aronoff et al 2010) and improvements in speech understanding in noise largely result from attending to the ear with the best signal-to-noise ratio (van Hoesel and Tyler 2003;Schleich et al 2004;Litovsky et al 2006). Importantly, bilateral CI users receive minimal benefit from interaural time difference (ITD) cues (van Hoesel 2012), which provide the greatest benefit to normal-hearing listeners in everyday situations (Bronkhorst and Plomp 1992;Zurek 1992;Macpherson and Middlebrooks 2002).…”

Aging and Speech-on-Speech Masking

“…In theory, a masker consisting of a small number of voices should produce less masking than a steady state noise as listeners can take advantage of brief fluctuations in the masker to reduce its efficiency (e.g., Festen & Plomp, 1990). However, the peripheral hearing loss that accompanies aging limits this advantage (e.g., Bronkhorst & Plomp, 1992;Carhart & Tillman, 1970;Hygge, Ronnberg, Larsby, & Arlinger, 1992;Moore, Glasberg, & Vickers, 1995;Peters, Moore, & Baer, 1998;Takahashi & Bacon, 1992). Age-related changes other than auditory threshold elevation also may contribute to a decreased ability to take advantage of spectral and/or temporal fluctuations in a masker (Dubno, Horwitz, & Ahlstrom, 2002George, Festen, & Houtgast, 2006;Peters, et al, 1998;Stuart & Phillips, 1996).…”