ABSTRACT
This study investigated whether spatial separation between talkers helps reduce cognitive processing load, and how hearing impairment interacts with the cognitive load of individuals listening in multi-talker environments. A dual-task paradigm was used in which performance on a secondary task (visual tracking) served as a measure of the cognitive load imposed by a speech recognition task. Visual tracking performance was measured under four conditions in which the target and the interferers were distinguished by (1) gender and spatial location, (2) gender only, (3) spatial location only, and (4) neither gender nor spatial location. Results showed that when gender cues were available, a 15° spatial separation between talkers reduced the cognitive load of listening even though it did not provide further improvement in speech recognition (Experiment I). Compared to normal-hearing listeners, large individual variability in spatial release of cognitive load was observed among hearing-impaired listeners. Cognitive load was lower when talkers were spatially separated by 60° than when talkers were of different genders, even though speech recognition was comparable in these two conditions (Experiment II). These results suggest that a measure of cognitive load might provide valuable insight into the benefit of spatial cues in multi-talker environments.
Subject(s)
Cognition/physiology , Hearing Loss/physiopathology , Hearing/physiology , Acoustic Stimulation , Aged , Audiometry, Speech , Cues , Female , Humans , Male , Middle Aged , Psychomotor Performance/physiology , Space Perception , Speech Perception/physiologyABSTRACT
Auditive and cognitive influences on speech perception in a complex situation were investigated in listeners with normal hearing (NH) and hearing loss (HL). The speech corpus used was the Nonsense-Syllable Response Measure [NSRM; Woods and Kalluri, (2010). International Hearing Aid Research Conference, pp. 40-41], a 12-talker corpus which combines 154 nonsense syllables with 8 different carrier phrases. Listeners heard NSRM sentences in quiet, background noise, and in background noise plus other "jammer" NSRM sentences. All stimuli were linearly amplified. A "proficiency" value, determined from the results in quiet and the quiet-condition speech intelligibility index (SII), was used with the SII in predicting results in the other conditions. Results for nine of ten NH subjects were well-predicted (within the limits of binomial variability) in the noise condition, as were eight of these subjects in the noise-plus-jammers condition. All 16 HL results were well-predicted in the noise condition, as were 9 of the HL in the noise-plus-jammers condition. Hierarchical regression partialling out the effects of age found proficiency in noise-plus-jammers significantly correlated with results of "trail-making" tests, thought to index processing speed and attention-deployment ability, and proficiency in quiet and noise was found significantly correlated with results from a backward digit-span memory test.
Subject(s)
Hearing Aids , Hearing Loss, Sensorineural/diagnosis , Loudness Perception , Perceptual Masking , Speech Perception , Speech Reception Threshold Test , Adult , Aged , Attention , Auditory Threshold , Female , Hearing Loss, Sensorineural/psychology , Humans , Male , Memory, Short-Term , Middle Aged , Reaction Time , Sound Spectrography , Speech Acoustics , Trail Making TestABSTRACT
When normal-hearing (NH) listeners compare the loudness of narrowband and wideband sounds presented at identical sound pressure levels, the wideband sound will most often be perceived as louder than the narrowband sound, a phenomenon referred to as loudness summation. Hearing-impaired (HI) listeners typically show less-than-normal loudness summation, due to reduced cochlear compressive gain and degraded frequency selectivity. In the present study, loudness summation at 1 and 3 kHz was estimated monaurally for five NH and eight HI listeners by matching the loudness of narrowband and wideband noise stimuli. The loudness summation was measured as a function both of noise bandwidth and level. The HI listeners were tested unaided and aided using three different compression systems to investigate the possibility of restoring loudness summation in these listeners. A compression system employing level-dependent compression channels yielded the most promising outcome. The present results inform the development of future loudness models and advanced compensation strategies for the hearing impaired.
