Auditory Perception in Individuals with Friedreich’s Ataxia

Introduction: Friedreich’s ataxia (FRDA) is an inherited ataxia with a range of progressive features including axonal degeneration of sensory nerves. The aim of this study was to investigate auditory perception in affected individuals. Methods: Fourteen subjects with genetically defined FRDA participated. Two control groups, one consisting of healthy, normally hearing individuals and another comprised of subjects with sensorineural hearing loss, were also assessed. Auditory processing was evaluated using structured tasks designed to reveal the listeners’ ability to perceive temporal and spectral cues. Findings were then correlated with open-set speech understanding. Results: Nine of 14 individuals with FRDA showed evidence of auditory processing disorder. Gap and amplitude modulation detection levels in these subjects were significantly elevated, indicating impaired encoding of rapid signal changes. Electrophysiologic findings (auditory brainstem response, ABR) also reflected disrupted neural activity. Speech understanding was significantly affected in these listeners and the degree of disruption was related to temporal processing ability. Speech analyses indicated that timing cues (notably consonant voice onset time and vowel duration) were most affected. Conclusion: The results suggest that auditory pathway abnormality is a relatively common consequence of FRDA. Regular auditory evaluation should therefore be part of the management regime for all affected individuals. This assessment should include both ABR testing, which can provide insights into the degree to which auditory neural activity is disrupted, and some functional measure of hearing capacity such as speech perception assessment, which can quantify the disorder and provide a basis for intervention.

from Audiology & Neuro-Otology

Development of a Danish speech intelligibility test

A Danish speech intelligibility test for assessing the speech recognition threshold in noise (SRTN) has been developed. The test consists of 180 sentences distributed in 18 phonetically balanced lists. The sentences are based on an open word-set and represent everyday language. The sentences were equalized with respect to intelligibility to ensure uniform SRTN assessments with all lists. In contrast to several previously developed tests such as the hearing in noise test (HINT) where the equalization is based on scored (objective) measures of word intelligibility, the present test used an equalization method based on subjective assessments of the sentences. The new equalization method is shown to create lists with less variance between the SRTNs than the traditional method. The number of sentence levels included in the SRTN calculation was also evaluated and differs from previous tests. The test was verified with 14 normal-hearing listeners; the overall SRTN lies at a signal-to-noise ratio of -3.15 dB with a standard deviation of 1.0 dB. The list-SRTNs deviate less than 0.5 dB from the overall mean.

from the International Journal of Audiology

Development of the Mandarin pediatric speech intelligibility (MPSI) test

The objective of this research was to create a Mandarin closed-set sentence recognition test based on the English pediatric speech intelligibility (PSI) test (Jerger & Jerger, 1984) for evaluation of speech perception in children as young as three years of age. Developmentally normal children (N = 93), 3-6 years of age, were administered the Mandarin PSI (MPSI) via a computer-controlled protocol. Perfect performance was observed for all children in quiet and at +10 and +5 dB signal-to-noise ratios (SNRs). Significant age and developmental trends were seen for the more difficult SNRs, 0 dB, -5 dB, and -10 dB, with 75% of 5-6 year olds reaching the most difficult SNR. Children who reached each of the more difficult SNRs, regardless of age, exhibited the same pattern of performance on all easier conditions, indicating that the final SNR achieved, rather than percent correct scores, may be a better descriptor of performance. The MPSI comprises part of a hierarchical assessment battery for pediatric speech perception for evaluation of intervention alternatives for Mandarin-speaking children with hearing impairment.

from the International Journal of Audiology

Perception of speech with envelope enhancement in individuals with auditory neuropathy and simulated loss of temporal modulation processing

Individuals with auditory neuropathy (AN) often suffer from temporal processing deficits causing speech perception difficulties. In the present study an envelope enhancement scheme that incorporated envelope expansion was used to reduce the effects of temporal deficits. The study involved two experiments. In the first experiment, to simulate the effects of reduced temporal resolution, temporally smeared speech stimuli were presented to listeners with normal hearing. The results revealed that temporal smearing of the speech signal reduced identification scores. With the envelope enhancement of the speech signal prior to being temporally smeared, identification scores improved significantly compared to temporally smeared condition. The second experiment assessed speech perception in twelve individuals with AN, using unprocessed and envelope-enhanced speech signals. The results revealed improvement in speech identification scores for the majority of individuals with AN when the envelope of the speech signal was enhanced. However, envelope enhancement was not able to improve speech identification scores for individuals with AN who had very poor unprocessed speech scores. Overall, the results of the present study suggest that applying envelope enhancement strategies in hearing aids might provide some benefits to many individuals with AN.

from the International Journal of Audiology

Primary and multisensory cortical activity is correlated with audiovisual percepts

Incongruent auditory and visual stimuli can elicit audiovisual illusions such as the McGurk effect where visual /ka/ and auditory /pa/ fuse into another percept such as/ta/. In the present study, human brain activity was measured with adaptation functional magnetic resonance imaging to investigate which brain areas support such audiovisual illusions. Subjects viewed trains of four movies beginning with three congruent /pa/ stimuli to induce adaptation. The fourth stimulus could be (i) another congruent /pa/, (ii) a congruent /ka/, (iii) an incongruent stimulus that evokes the McGurk effect in susceptible individuals (lips /ka/ voice /pa/), or (iv) the converse combination that does not cause the McGurk effect (lips /pa/ voice/ ka/). This paradigm was predicted to show increased release from adaptation (i.e. stronger brain activation) when the fourth movie and the related percept was increasingly different from the three previous movies. A stimulus change in either the auditory or the visual stimulus from /pa/ to /ka/ (iii, iv) produced within-modality and cross-modal responses in primary auditory and visual areas. A greater release from adaptation was observed for incongruent non-McGurk (iv) compared to incongruent McGurk (iii) trials. A network including the primary auditory and visual cortices, nonprimary auditory cortex, and several multisensory areas (superior temporal sulcus, intraparietal sulcus, insula, and pre-central cortex) showed a correlation between perceiving the McGurk effect and the fMRI signal, suggesting that these areas support the audiovisual illusion. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc.

from Human Brain Mapping

Sensory-motor brain network connectivity for speech comprehension

Abstract
The act of listening to speech activates a large network of brain areas. In the present work, a novel data-driven technique (the combination of independent component analysis and Granger causality) was used to extract brain network dynamics from an fMRI study of passive listening to Words, Pseudo-Words, and Reverse-played words. Using this method we show the functional connectivity modulations among classical language regions (Broca’s and Wernicke’s areas) and inferior parietal, somatosensory, and motor areas and right cerebellum. Word listening elicited a compact pattern of connectivity within a parieto-somato-motor network and between the superior temporal and inferior frontal gyri. Pseudo-Word stimuli induced activities similar to the Word condition, which were characterized by a highly recurrent connectivity pattern, mostly driven by the temporal lobe activity. Also the Reversed-Word condition revealed an important influence of temporal cortices, but no integrated activity of the parieto-somato-motor network. In parallel, the right cerebellum lost its functional connection with motor areas, present in both Word and Pseudo-Word listening. The inability of the participant to produce the Reversed-Word stimuli also evidenced two separate networks: the first was driven by frontal areas and the right cerebellum toward somatosensory cortices; the second was triggered by temporal and parietal sites towards motor areas. Summing up, our results suggest that semantic content modulates the general compactness of network dynamics as well as the balance between frontal and temporal language areas in driving those dynamics. The degree of reproducibility of auditory speech material modulates the connectivity pattern within and toward somatosensory and motor areas. Hum Brain Mapp, 2009. © 2009 Wiley-Liss, Inc.

from Human Brain Mapping

Perceptual learning of co-articulation in speech

Four experiments investigated the novel issue of learning to accommodate the co-articulated nature of speech. Experiment 1 established a co-articulatory mismatch effect for a set of vowel–consonant (VC) syllables (reaction times were faster for co-articulation matching than for mismatching stimuli). A rhyme judgment training task on words (Experiment 2) or VC stimuli (Experiment 3) with mismatching information was followed by a phoneme monitoring task on a set of VC stimuli; training and test stimuli contained physically identical (same condition) or new (different condition) mismatching co-articulatory information (along with a set containing matching co-articulatory information). A third group received no training. A co-articulatory mismatch effect was found without training but not when the same mismatching tokens were used at training and test. Both word (Experiment 2) and syllable (Experiment 3) training stimuli eliminated the mismatch effect; overall reaction times were somewhat slower when the training stimuli were words. Perceptual learning generalized to new tokens only when the acoustic manifestation of the critical co-articulatory information in the training stimuli was sufficiently large (Experiments 3 and 4). The results are discussed in terms of speech processing and perceptual learning in speech perception.

from the Journal of Memory and Language

Speech perception and phonological short-term memory capacity in language impairment: preliminary evidence from adolescents with specific language impairment (SLI) and autism spectrum disorders (ASD)

Background: The cognitive bases of language impairment in specific language impairment (SLI) and autism spectrum disorders (ASD) were investigated in a novel non-word comparison task which manipulated phonological short-term memory (PSTM) and speech perception, both implicated in poor non-word repetition.

Aims: This study aimed to investigate the contributions of PSTM and speech perception in non-word processing and whether individuals with SLI and ASD plus language impairment (ALI) show similar or different patterns of deficit in these cognitive processes.

Method & Procedures: Three groups of adolescents (aged 14-17 years), 14 with SLI, 16 with ALI, and 17 age and non-verbal IQ matched typically developing (TD) controls, made speeded discriminations between non-word pairs. Stimuli varied in PSTM load (two- or four-syllables) and speech perception load (mismatches on a word-initial or word-medial segment).

Outcomes & Results: Reaction times showed effects of both non-word length and mismatch position and these factors interacted: four-syllable and word-initial mismatch stimuli resulted in the slowest decisions. Individuals with language impairment showed the same pattern of performance as those with typical development in the reaction time data. A marginal interaction between group and item length was driven by the SLI and ALI groups being less accurate with long items than short ones, a difference not found in the TD group.

Conclusions & Implications: Non-word discrimination suggests that there are similarities and differences between adolescents with SLI and ALI and their TD peers. Reaction times appear to be affected by increasing PSTM and speech perception loads in a similar way. However, there was some, albeit weaker, evidence that adolescents with SLI and ALI are less accurate than TD individuals, with both showing an effect of PSTM load. This may indicate, at some level, the processing substrate supporting both PSTM and speech perception is intact in adolescents with SLI and ALI, but also in both there may be impaired access to PSTM resources.

from the International Journal of Language and Communication Disorders

Audiovisual asynchrony detection and speech perception in hearing-impaired listeners with cochlear implants: A preliminary analysis

This preliminary study examined the effects of hearing loss and aging on the detection of AV asynchrony in hearing-impaired listeners with cochlear implants. Additionally, the relationship between AV asynchrony detection skills and speech perception was assessed. Individuals with normal-hearing and cochlear implant recipients were asked to make judgments about the synchrony of AV speech. The cochlear implant recipients also completed three speech perception tests, the CUNY, HINT sentences, and the CNC test. No significant differences were observed in the detection of AV asynchronous speech between the normal-hearing listeners and the cochlear implant recipients. Older adults in both groups displayed wider timing windows, over which they identified AV asynchronous speech as being synchronous, than younger adults. For the cochlear implant recipients, no relationship between the size of the temporal asynchrony window and speech perception performance was observed. The findings from this preliminary experiment suggest that aging has a greater effect on the detection of AV asynchronous speech than the use of a cochlear implant. Additionally, the temporal width of the AV asynchrony function was not correlated with speech perception skills for hearing-impaired individuals who use cochlear implants.

from the International Journal of Audiology

Multiple benefits of personal FM system use by children with auditory processing disorder (APD)

Children with auditory processing disorders (APD) were fitted with Phonak EduLink FM devices for home and classroom use. Baseline measures of the children with APD, prior to FM use, documented significantly lower speech-perception scores, evidence of decreased academic performance, and psychosocial problems in comparison to an age- and gender-matched control group. Repeated measures during the school year demonstrated speech-perception improvement in noisy classroom environments as well as significant academic and psychosocial benefits. Compared with the control group, the children with APD showed greater speech-perception advantage with FM technology. Notably, after prolonged FM use, even unaided (no FM device) speech-perception performance was improved in the children with APD, suggesting the possibility of fundamentally enhanced auditory system function.

from the International Journal of Audiology

Perceiving the Effects of Ethanol Intoxication on Voice

Many conditions operate to degrade the quality of the human voice. Alcohol intoxication is one of them. In this project, the objectives were to examine the ability of human listeners to accurately estimate both the presence and severity of intoxication from two types of speech samples. A review of available data suggests that, although listeners can often identify individuals who are intoxicated simply by hearing samples of their voice, they are less efficient at accurately determining the severity of this condition. A number of aural-perceptual studies were carried out to test these relationships. Populations of speakers, selected based on rigorous criteria, provided orally read and extemporaneous utterances when sober and at three highly controlled levels of intoxication. Listener groups of university students and professionals attempted to identify both the existence and specific level of intoxication present. It was found that these individuals were proficient in recognizing the presence of, and increases in, intoxication but were less accurate in gauging the specific levels. Several subordinate relationships were also investigated. In this regard, statistically significant differences were not found between male and female listeners or between professionals and lay listeners; however, they were found for different classes of speech. That is, it was shown that text difficulty correlated with severity of effect.

from the Journal of Voice

Assessing binaural/bimodal advantages using auditory event-related potentials in subjects with cochlear implants

Better speech perception was obtained for binaural and bimodal hearing than for monaural hearing in CI subjects. The results obtained in the comparison of P3 latency agreed with that of speech perception. Thus, using bilateral hearing devices is recommended for CI subjects. We also found that event-related potentials were useful as an objective tool to assess the advantage of binaural and bimodal hearing for CI subjects.

from Auris Nasus Larynx

Normal-hearing English-as-a-second-language listeners’ recognition of English words in competing signals

English-as-a-second-language (ESL) listeners have difficulty perceiving English speech presented in background noise. The current study furthered this line of investigations by including participants who varied widely in their age of English acquisition and length of English learning: 24 native English monolingual (EML), 12 simultaneous bilingual (SBL), 10 early ESL (E-ESL), and 14 late ESL (L-ESL) listeners. Word recognition scores were obtained in quiet and in the presence of speech-weighted noise, multi-talker babble, forward-playing music, and time-reversed music. All words and competing signals were presented at 45 dB HL. EML and SBL listeners’ performances were found to be similar across test conditions. ESL, especially L-ESL listeners, performed significantly more poorly in all conditions than EML and SBL listeners. Overall, speech-weighted noise and multi-talker babble showed greater masking effect than music; however, the difference in performance between L-ESL and EML listeners was the largest for the music maskers, indicating that L-ESL listeners are susceptible to weaker maskers. Age of acquisition and length of learning were both shown to be good indicators of SBL and ESL listeners’ performance.

from the International Journal of Audiology

Normal-hearing English-as-a-second-language listeners’ recognition of English words in competing signals

English-as-a-second-language (ESL) listeners have difficulty perceiving English speech presented in background noise. The current study furthered this line of investigations by including participants who varied widely in their age of English acquisition and length of English learning: 24 native English monolingual (EML), 12 simultaneous bilingual (SBL), 10 early ESL (E-ESL), and 14 late ESL (L-ESL) listeners. Word recognition scores were obtained in quiet and in the presence of speech-weighted noise, multi-talker babble, forward-playing music, and time-reversed music. All words and competing signals were presented at 45 dB HL. EML and SBL listeners’ performances were found to be similar across test conditions. ESL, especially L-ESL listeners, performed significantly more poorly in all conditions than EML and SBL listeners. Overall, speech-weighted noise and multi-talker babble showed greater masking effect than music; however, the difference in performance between L-ESL and EML listeners was the largest for the music maskers, indicating that L-ESL listeners are susceptible to weaker maskers. Age of acquisition and length of learning were both shown to be good indicators of SBL and ESL listeners’ performance.

from the International Journal of Audiology

Relationships between speech perception abilities and spoken language skills in young children with hearing loss

The goal of this study was to examine the relationships between scores obtained from measures of speech perception and language in a group of young children with hearing loss (HL). Eighteen children (mean age = 4.3 years) and their mothers participated in this study. Speech perception was measured using the online imitative test of speech pattern contrast perception (OLIMSPAC). Standardized language age equivalent scores were obtained using the Reynell developmental language scales-III. Number of word tokens, word types, and mean length of utterance (MLU) were extracted from the children’s spontaneous language samples. Significant positive relationships were observed between children’s OLIMSPAC scores and both standardized language scores (r ranging from 0.60 to 0.69; p <0.01) and all measures derived from children's spontaneous language samples (r ranging from 0.80 to 0.86; p<0.01). After controlling for child age, OLIMSPAC scores explained 34.1% of the variance in children's MLU. Using a new speech perception measure with reduced language demands, strong positive correlations were evident between speech perception and language skills for a young group of children with HL.

from the International Journal of Audiology