The importance of interaural time differences and level differences in spatial release from masking

Numerous studies have described improvements in speech understanding when interaural time differences (ITDs) and interaural level differences (ILDs) are present. The present study aimed to investigate whether either cue in isolation can elicit spatial release from masking (SRM) in a speech-on-speech masking paradigm with maskers positioned symmetrically around the listener. Twelve adults were tested using three presentations of the Listening in Spatialized Noise-Sentences Test, with each presentation modified to contain different interaural cues in the stimuli. Results suggest that ILDs provide a similar amount of SRM as ITDs and ILDs combined. ITDs alone provide significantly less benefit. (C) 2013 Acoustical Society of Americ

Effect of audibility on spatial release from speech-on-speech masking

This study investigated to what extent spatial release from masking (SRM) deficits in hearing-impaired adults may be related to reduced audibility of the test stimuli. Sixteen adults with sensorineural hearing loss and 28 adults with normal hearing were assessed on the Listening in Spatialized Noise–Sentences test, which measures SRM using a symmetric speech-on-speech masking task. Stimuli for the hearing-impaired listeners were delivered using three amplification levels (National Acoustic Laboratories - Revised Profound prescription (NAL-RP) +25%, and NAL-RP +50%), while stimuli for the normal-hearing group were filtered to achieve matched audibility. SRM increased as audibility increased for all participants. Thus, it is concluded that reduced audibility of stimuli may be a significant factor in hearing-impaired adults' reduced SRM even when hearing loss is compensated for with linear gain. However, the SRM achieved by the normal hearers with simulated audibility loss was still significantly greater than that achieved by hearing-impaired listeners, suggesting other factors besides audibility may still play a role

Listening in spatialized noise - Sentences test (LiSN-S):normative and retest reliability data for adolescents and adults up to 60 years of age

Background: The Australian version of the Listening in Spatialized Noise—Sentences Test (LiSN-S) was originally developed to assess auditory stream segregation skills in children aged 6 to 11 yr with suspected central auditory processing disorder. The LiSN-S creates a three-dimensional auditory environment under headphones. A simple repetition-response protocol is used to assess a listener's speech reception threshold (SRT) for target sentences presented in competing speech maskers. Performance is measured as the improvement in SRT in decibels gained when either pitch, spatial, or both pitch and spatial cues are incorporated in the maskers. Purpose: To collect additional normative data on the Australian LiSN-S for adolescents and adults up to 60 yr of age, to analyze the effects of age on LiSN-S performance, to examine retest reliability in the older population, and to extrapolate findings from the Australian data so that the North American version of the test can also be used clinically with older adults. Research Design: In a descriptive design, normative and test–retest reliability data were collected from adolescents and adults and combined with previously published data from Australian children aged 6 to 11 yr. Study Sample: One hundred thirty-two participants with normal hearing aged 12 yr, 0 mo, to 60 yr, 7 mo, took part in the normative data study. Fifty-five participants returned between 2 and 4 mo after the initial assessment for retesting. Results: Analysis of variance revealed a significant effect of age on LiSN-S performance (p &lt; .01 for all LiSN-S measures, ηp 2 ranging from 0.16 to 0.54). On the low and high cue SRT measures, planned contrasts revealed significant differences between adults and children aged 13 yr and younger, as well as between 50- to 60-yr-olds and younger adults aged 18–29 yr. Whereas there were significant differences between adults and children on the talker, spatial, and total advantage measures, there were no significant differences in performance in adults aged 18–60 yr. There was a small but significant improvement on retest ranging from 0.5 to 1.2 dB across the four LiSN-S test conditions (p ranging from .01 to &lt;.001). However, there was no significant difference between test and retest on the advantage measures (p ranging from .143 to .768). Test–retest differences across all LiSN-S measures were significantly correlated (r ranging from 0.2 to 0.7, p ranging from .023 to &lt;.00000001) and did not differ as a function of age (p ranging from .178 to .980). Conclusions: As there was no significant difference among adults aged 18–60 yr on the LiSN-S talker, spatial, and total advantage measures, it appears that the decline in ability to understand speech in noise experienced by 50- to 60-yr-olds is not related to their ability to use either spatial or pitch cues. This result suggests that some other factor/s contributes to the decline in speech perception in noise experienced by older adults that is reported in the literature and was demonstrated in this study on the LiSN-S low and high cue SRT measures.</jats:p

Efficacy of the LiSN &amp; Learn Auditory Training Software: randomized blinded controlled study

Background: Children with a spatial processing disorder (SPD) require a more favorable signal-to-noise ratio in the classroom because they have difficulty perceiving sound source location cues. Previous research has shown that a novel training program - LiSN &amp;amp; Learn - employing spatialized sound, overcomes this deficit. Here we investigate whether improvements in spatial processing ability are specific to the LiSN &amp;amp; Learn training program. Materials and methods: Participants were ten children (aged between 6;0 [years;months] and 9;9) with normal peripheral hearing who were diagnosed as having SPD using the Listening in Spatialized Noise – Sentences Test (LISN-S). In a blinded controlled study, the participants were randomly allocated to train with either the LiSN &amp;amp; Learn or another auditory training program – Earobics - for approximately 15 minutes per day for twelve weeks. Results: There was a significant improvement post-training on the conditions of the LiSN-S that evaluate spatial processing ability for the LiSN &amp;amp; Learn group (p=0.03 to 0.0008, η2=0.75 to 0.95, n=5), but not for the Earobics group (p=0.5 to 0.7, η2=0.1 to 0.04, n=5). Results from questionnaires completed by the participants and their parents and teachers revealed improvements in real-world listening performance post-training were greater in the LiSN &amp;amp; Learn group than the Earobics group. Conclusions: LiSN &amp;amp; Learn training improved binaural processing ability in children with SPD, enhancing their ability to understand speech in noise. Exposure to non-spatialized auditory training does not produce similar outcomes, emphasizing the importance of deficit-specific remediation

Efficacy of the LiSN & Learn auditory training software: randomized blinded controlled study

Children with a spatial processing disorder (SPD) require a more favorable signal-to-noise ratio in the classroom because they have difficulty perceiving sound source location cues. Previous research has shown that a novel training program - LiSN & Learn - employing spatialized sound, overcomes this deficit. Here we investigate whether improvements in spatial processing ability are specific to the LiSN & Learn training program. Participants were ten children (aged between 6;0 [years;months] and 9;9) with normal peripheral hearing who were diagnosed as having SPD using the Listening in Spatialized Noise - Sentences test (LiSN-S). In a blinded controlled study, the participants were randomly allocated to train with either the LiSN & Learn or another auditory training program - Earobics - for approximately 15 min per day for twelve weeks. There was a significant improvement post-training on the conditions of the LiSN-S that evaluate spatial processing ability for the LiSN & Learn group (P=0.03 to 0.0008, η 2=0.75 to 0.95, n=5), but not for the Earobics group (P=0.5 to 0.7, η 2=0.1 to 0.04, n=5). Results from questionnaires completed by the participants and their parents and teachers revealed improvements in real-world listening performance post-training were greater in the LiSN & Learn group than the Earobics group. LiSN & Learn training improved binaural processing ability in children with SPD, enhancing their ability to understand speech in noise. Exposure to non-spatialized auditory training does not produce similar outcomes, emphasizing the importance of deficit-specific remediation

Investigating the interaction between dichotic deficits and cognitive abilities using the Dichotic Digits difference Test (DDdT) part 2

Background: The Dichotic Digits difference Test (DDdT) was developed to investigate the relationship between dichotic processing and cognitive abilities and, through the use of differential test scores, to provide professionals with a clinical tool that could aid in differentiation of clients with genuine dichotic deficits from those where cognitive disorders affect test performance. The DDdT consists of four subtests: dichotic free recall (FR), dichotic directed left ear, dichotic directed right ear, and diotic. Scores are calculated for six conditions: FR left ear (LE), right ear (RE), and total, as well as the directed left ear, directed right ear, and diotic, and four difference measures: dichotic advantage, RE advantage FR, RE advantage directed, and attention advantage. Purpose: To investigate the role of cognitive abilities on DDdT test performance. Research Design: Correlational analysis between the various DDdT conditions and difference measures, as well as between dichotic, diotic, and cognitive factors (memory, intelligence, and attention). Study Sample: Fifty typically developing children (aged 7 yr 0 mo to 12 yr 1 mo, mean = 9 yr 2 mo) and ten children recruited from the Australian Hearing CAPD Service who were diagnosed with a memory or dichotic deficit (aged 7 yr 0 mo to 15 yr 0 mo, mean = 9 yr 5 mo) took part in the study. Data Collection and Analysis: The Pearson product moment correlations were used to determine the strength of relationships between DDdT conditions as well as relationships between scores on these conditions and performance on the various cognitive assessment tools, which included the number memory forward and reversed subtests of the Test of Auditory Processing Skills ‐ Third Edition, IVA + Plus Continuous Performance Test, and the Test of Non-Verbal Intelligence-4 (TONI-4). A parent questionnaire (Fisher’s Auditory Checklist) and a participant questionnaire (Listening Inventory for Education) were also administered. Results: Diotic performance was significantly correlated with performance on all the DDdT dichotic FR conditions (r = 0.6‐0.8; p < 0.00001). Further, significant correlations were found between the FR LE, total, and diotic conditions, and the cognitive measures of attention and memory, with r ranging from 0.4 to 0.5 (p < 0.01‐0.001). Right-ear performance was not significantly correlated to any cognitive measure, except for FR RE and number memory forward (r = 0.35; p = 0.006). The DDdT dichotic advantage measure was investigated in a subset of clinical children and found to aid in differentiating true dichotic from spurious results. Conclusions: As found in the DDdT normative data study that precedes in the companion paper (DDdT Study Part 1; Cameron et al, 2016), the high correlation between dichotic and diotic performances by the clinical and typically developing participants suggests that factors other than dichotic performance play a substantial role in a child’s ability to perform a dichotic listening task. Indeed, 61% of the variance in FR total scores for the children in this study was accounted for by factors that do not involve the perception of dichotic stimuli. This view is supported by the correlations between measures of attention and memory and dichotic scores. This result has wide-spread implications in respect to interpretation of central auditory processing disorder test results and further investigation of the use of the DDdT in a clinical population is warranted.10 page(s

Remediation of spatial processing deficits in hearing-impaired children and adults

Background: The ability to use interaural cues to segregate target speech from competing signals allows people with normal hearing to understand speech at significantly poorer signal-to-noise ratio's. This ability, referred to as spatial processing ability or spatial release from masking, has been shown to be deficient in people with a sensorineural hearing loss even after amplification is applied. Spatial processing deficits in a population of children with auditory processing deficits have been found to be remediable through the use of a deficit-specific auditory training program called the LiSN & Learn