Evaluating earwitness identification procedures: adapting pre-parade instructions and parade procedure.

Voice identification parades can be unreliable, as earwitness responses are error-prone. In this paper we tested performance across serial and sequential procedures, and varied pre-parade instructions, with the aim of reducing errors. The participants heard a target voice and later attempted to identify it from a parade. In Experiment 1 they were either warned that the target may or may not be present (standard warning) or encouraged to consider responding "not present" because of the associated risk of a wrongful conviction (strong warning). Strong warnings prompted a conservative criterion shift, with participants less likely to make a positive identification regardless of whether the target was present. In contrast to previous findings, we found no statistically reliable difference in accuracy between serial and sequential parades. Experiment 2 ruled out a potential confound in Experiment 1. Taken together, our results suggest that adapting pre-parade instructions provides a simple way of reducing the risk of false identifications.

Audio-visual integration in noise: Influence of auditory and visual stimulus degradation on eye movements and perception of the McGurk effect.

Seeing a talker's face can aid audiovisual (AV) integration when speech is presented in noise. However, few studies have simultaneously manipulated auditory and visual degradation. We aimed to establish how degrading the auditory and visual signal affected AV integration. Where people look on the face in this context is also of interest; Buchan, Paré and Munhall (Brain Research, 1242, 162-171, 2008) found fixations on the mouth increased in the presence of auditory noise whilst Wilson, Alsius, Paré and Munhall (Journal of Speech, Language, and Hearing Research, 59(4), 601-615, 2016) found mouth fixations decreased with decreasing visual resolution. In Condition 1, participants listened to clear speech, and in Condition 2, participants listened to vocoded speech designed to simulate the information provided by a cochlear implant. Speech was presented in three levels of auditory noise and three levels of visual blurring. Adding noise to the auditory signal increased McGurk responses, while blurring the visual signal decreased McGurk responses. Participants fixated the mouth more on trials when the McGurk effect was perceived. Adding auditory noise led to people fixating the mouth more, while visual degradation led to people fixating the mouth less. Combined, the results suggest that modality preference and where people look during AV integration of incongruent syllables varies according to the quality of information available.

Voice parade procedures: optimising witness performance.

Unfamiliar voice identification is error-prone. Whilst the investigation of system variables may indicate ways of boosting earwitness performance, this is an under-researched area. Two experiments were conducted to investigate how methods of presenting voices during a parade affect accuracy and self-rated confidence. In each experiment participants listened to a target voice, and were later asked to identify that voice from a nine-person target present or target absent parade. In Experiment 1, accuracy did not vary across parades comprising 15 or 30 s sample durations. Overall, when the target was present, participants correctly identified the target voice with 39% accuracy. However, when the target was absent, participants correctly rejected the parade 6% of the time. There was no relationship between accuracy and confidence. In Experiment 2, performance with a serial procedure, in which participants responded after hearing all nine voices, was compared with a sequential procedure, in which participants made a decision after listening to each voice. Overall accuracy was higher with the sequential procedure. These results highlight the importance of system variable research in voice identification. Different methods of presenting voices have the potential to support higher levels of accuracy than the procedure currently recommended in England and Wales.

Visual Speech Benefit in Clear and Degraded Speech Depends on the Auditory Intelligibility of the Talker and the Number of Background Talkers.

Perceiving speech in background noise presents a significant challenge to listeners. Intelligibility can be improved by seeing the face of a talker. This is of particular value to hearing impaired people and users of cochlear implants. It is well known that auditory-only speech understanding depends on factors beyond audibility. How these factors impact on the audio-visual integration of speech is poorly understood. We investigated audio-visual integration when either the interfering background speech (Experiment 1) or intelligibility of the target talkers (Experiment 2) was manipulated. Clear speech was also contrasted with sine-wave vocoded speech to mimic the loss of temporal fine structure with a cochlear implant. Experiment 1 showed that for clear speech, the visual speech benefit was unaffected by the number of background talkers. For vocoded speech, a larger benefit was found when there was only one background talker. Experiment 2 showed that visual speech benefit depended upon the audio intelligibility of the talker and increased as intelligibility decreased. Degrading the speech by vocoding resulted in even greater benefit from visual speech information. A single "independent noise" signal detection theory model predicted the overall visual speech benefit in some conditions but could not predict the different levels of benefit across variations in the background or target talkers. This suggests that, similar to audio-only speech intelligibility, the integration of audio-visual speech cues may be functionally dependent on factors other than audibility and task difficulty, and that clinicians and researchers should carefully consider the characteristics of their stimuli when assessing audio-visual integration.

The threshold for the McGurk effect in audio-visual noise decreases with development.

Across development, vision increasingly influences audio-visual perception. This is evidenced in illusions such as the McGurk effect, in which a seen mouth movement changes the perceived sound. The current paper assessed the effects of manipulating the clarity of the heard and seen signal upon the McGurk effect in children aged 3-6 (n = 29), 7-9 (n = 32) and 10-12 (n = 29) years, and adults aged 20-35 years (n = 32). Auditory noise increased, and visual blur decreased, the likelihood of vision changing auditory perception. Based upon a proposed developmental shift from auditory to visual dominance we predicted that younger children would be less susceptible to McGurk responses, and that adults would continue to be influenced by vision in higher levels of visual noise and with less auditory noise. Susceptibility to the McGurk effect was higher in adults compared with 3-6-year-olds and 7-9-year-olds but not 10-12-year-olds. Younger children required more auditory noise, and less visual noise, than adults to induce McGurk responses (i.e. adults and older children were more easily influenced by vision). Reduced susceptibility in childhood supports the theory that sensory dominance shifts across development and reaches adult-like levels by 10 years of age.

The effect of inserting an inter-stimulus interval in face-voice matching tasks.

Voices and static faces can be matched for identity above chance level. No previous face-voice matching experiments have included an inter-stimulus interval (ISI) exceeding 1 s. We tested whether accurate identity decisions rely on high-quality perceptual representations temporarily stored in sensory memory, and therefore whether the ability to make accurate matching decisions diminishes as the ISI increases. In each trial, participants had to decide whether an unfamiliar face and voice belonged to the same person. The face and voice stimuli were presented simultaneously in Experiment 1, and there was a 5-s ISI in Experiment 2, and a 10-s interval in Experiment 3. The results, analysed using multilevel modelling, revealed that static face-voice matching was significantly above chance level only when the stimuli were presented simultaneously (Experiment 1). The overall bias to respond same identity weakened as the interval increased, suggesting that this bias is explained by temporal contiguity. Taken together, the findings highlight that face-voice matching performance is reliant on comparing fast-decaying, high-quality perceptual representations. The results are discussed in terms of social functioning.

The contribution of visual information to the perception of speech in noise with and without informative temporal fine structure.

Understanding what is said in demanding listening situations is assisted greatly by looking at the face of a talker. Previous studies have observed that normal-hearing listeners can benefit from this visual information when a talker's voice is presented in background noise. These benefits have also been observed in quiet listening conditions in cochlear-implant users, whose device does not convey the informative temporal fine structure cues in speech, and when normal-hearing individuals listen to speech processed to remove these informative temporal fine structure cues. The current study (1) characterised the benefits of visual information when listening in background noise; and (2) used sine-wave vocoding to compare the size of the visual benefit when speech is presented with or without informative temporal fine structure. The accuracy with which normal-hearing individuals reported words in spoken sentences was assessed across three experiments. The availability of visual information and informative temporal fine structure cues was varied within and across the experiments. The results showed that visual benefit was observed using open- and closed-set tests of speech perception. The size of the benefit increased when informative temporal fine structure cues were removed. This finding suggests that visual information may play an important role in the ability of cochlear-implant users to understand speech in many everyday situations. Models of audio-visual integration were able to account for the additional benefit of visual information when speech was degraded and suggested that auditory and visual information was being integrated in a similar way in all conditions. The modelling results were consistent with the notion that audio-visual benefit is derived from the optimal combination of auditory and visual sensory cues.

Matching novel face and voice identity using static and dynamic facial images.

Research investigating whether faces and voices share common source identity information has offered contradictory results. Accurate face-voice matching is consistently above chance when the facial stimuli are dynamic, but not when the facial stimuli are static. We tested whether procedural differences might help to account for the previous inconsistencies. In Experiment 1, participants completed a sequential two-alternative forced choice matching task. They either heard a voice and then saw two faces or saw a face and then heard two voices. Face-voice matching was above chance when the facial stimuli were dynamic and articulating, but not when they were static. In Experiment 2, we tested whether matching was more accurate when faces and voices were presented simultaneously. The participants saw two face-voice combinations, presented one after the other. They had to decide which combination was the same identity. As in Experiment 1, only dynamic face-voice matching was above chance. In Experiment 3, participants heard a voice and then saw two static faces presented simultaneously. With this procedure, static face-voice matching was above chance. The overall results, analyzed using multilevel modeling, showed that voices and dynamic articulating faces, as well as voices and static faces, share concordant source identity information. It seems, therefore, that above-chance static face-voice matching is sensitive to the experimental procedure employed. In addition, the inconsistencies in previous research might depend on the specific stimulus sets used; our multilevel modeling analyses show that some people look and sound more similar than others.

Searching for a talking face: the effect of degrading the auditory signal.

Previous research (e.g., McGurk & MacDonald, 1976) suggests that faces and voices are bound automatically, but recent evidence suggests that attention is involved in a task of searching for a talking face (Alsius & Soto-Faraco, 2011). We hypothesized that the processing demands of the stimuli may affect the amount of attentional resources required, and investigated what effect degrading the auditory stimulus had on the time taken to locate a talking face. Twenty participants were presented with between 2 and 4 faces articulating different sentences, and had to decide which of these faces matched the sentence that they heard. The results showed that in the least demanding auditory condition (clear speech in quiet), search times did not significantly increase when the number of faces increased. However, when speech was presented in background noise or was processed to simulate the information provided by a cochlear implant, search times increased as the number of faces increased. Thus, it seems that the amount of attentional resources required vary according to the processing demands of the auditory stimuli, and when processing load is increased then faces need to be individually attended to in order to complete the task. Based on these results we would expect cochlear-implant users to find the task of locating a talking face more attentionally demanding than normal hearing listeners.

The efficacy of auditory perceptual training for tinnitus: a systematic review.

Auditory perceptual training affects neural plasticity and so represents a potential strategy for tinnitus management. We assessed the effects of auditory perceptual training on tinnitus perception and/or its intrusiveness via a systematic review of published literature. An electronic database search using the keywords 'tinnitus and learning' or 'tinnitus and training' was conducted, updated by a hand search. The ten studies identified were reviewed independently by two reviewers, data were extracted, study quality was assessed according to a number of specific criteria and the information was synthesised using a narrative approach. Nine out of the ten studies reported some significant change in either self-reported or psychoacoustic outcome measures after auditory training. However, all studies were quality rated as providing low or moderate levels of evidence for an effect. We identify a need for appropriately randomised and controlled studies that will generate high-quality unbiased and generalisable evidence to ascertain whether or not auditory perceptual training has a clinically relevant effect on tinnitus.

Effectiveness of computer-based auditory training for adult users of cochlear implants.

Cochlear implantation is effective at restoring partial hearing to profoundly deaf adults, but not all patients receive equal benefit. The present study evaluated the effectiveness of a computer-based self-administered training package that was designed to improve speech perception among adults who had used cochlear implants for more than three years. Eleven adults were asked to complete an hour of auditory training each day, five days a week, for a period of three weeks. Two training tasks were included, one based around discriminating isolated words, and the other around discriminating words in sentences. Compliance with the protocol was good, with eight out of eleven participants completing approximately 15 hours of training, as instructed. A significant improvement of eight percentage points was found on a test of consonant discrimination, but there were no significant improvements on sentence tests or on a test of vowel discrimination. Self-reported benefits were variable and generally small. Further research is needed to establish whether auditory training is particularly effective for identifiable sub-groups of cochlear-implant users.

Comparison of word-, sentence-, and phoneme-based training strategies in improving the perception of spectrally distorted speech.

PURPOSE: To compare the effectiveness of 3 self-administered strategies for auditory training that might improve speech perception by adult users of cochlear implants. The strategies are based, respectively, on discriminating isolated words, words in sentences, and phonemes in nonsense syllables. METHOD: Participants were 18 normal-hearing adults who listened to speech processed by a noise-excited vocoder to simulate the information provided by a cochlear implant. They were assigned randomly to word-, sentence-, or phoneme-based training and underwent 9 training sessions (20 min each) on separate days over a 2- to 3-week period. The effectiveness of training was assessed as the improvement in accuracy of discriminating vowels and consonants, as well as identifying words in sentences, relative to participants' best performance in repeated tests prior to training. RESULTS: Word- and sentence-based training led to significant improvements in the ability to identify words in sentences that were significantly larger than the improvements produced by phoneme-based training. There were no significant differences between the effectiveness of word- and sentence-based training. No significant improvements in consonant or vowel discrimination were found for the sentence- or phoneme-based training groups, but some improvements were found for the word-based training group. CONCLUSION: The word- and sentence-based training strategies were more effective than the phoneme-based strategy at improving the perception of spectrally distorted speech.

Effectiveness of computer-based auditory training in improving the perception of noise-vocoded speech.

Five experiments were designed to evaluate the effectiveness of "high-variability" lexical training in improving the ability of normal-hearing subjects to perceive noise-vocoded speech that had been spectrally shifted to simulate tonotopic misalignment. Two approaches to training were implemented. One training approach required subjects to recognize isolated words, while the other training approach required subjects to recognize words in sentences. Both approaches to training improved the ability to identify words in sentences. Improvements following a single session (lasting 1-2 h) of auditory training ranged between 7 and 12 %pts and were significantly larger than improvements following a visual control task that was matched with the auditory training task in terms of the response demands. An additional three sessions of word- and sentence-based training led to further improvements, with the average overall improvement ranging from 13 to 18% pts. When a tonotopic misalignment of 3 mm rather than 6 mm was simulated, training with several talkers led to greater generalization to new talkers than training with a single talker. The results confirm that computer-based lexical training can help overcome the effects of spectral distortions in speech, and they suggest that training materials are most effective when several talkers are included.

Hearing-impaired children in the United Kingdom, III: cochlear implantation and the economic costs incurred by families.

OBJECTIVES: This article addresses two questions. First, are there differences in the economic costs incurred by families of hearing-impaired children depending on whether or not children have cochlear implants? Second, are these differences important when assessed from the perspective of society? METHODS: In a cross-sectional survey, parents of a representative sample of hearing-impaired children provided data about annual resources used by the family because of their child's hearing impairment. The data yielded estimates of two variables: out-of-pocket expenditure and time away from normal activities by parents. The economic cost of the two variables was estimated in euros at 2001/2 price levels, and summed to estimate the overall economic cost incurred by the family. Linear regression was used to estimate the association between costs and implantation, while controlling for average (unaided, preoperative) hearing level, age at onset of hearing impairment, age, gender, the number of additional disabilities, parental occupational skill level, ethnicity, and parental hearing status. The cumulative economic cost incurred by the families of implanted children, between implantation and age 16 yr, was calculated from estimates of the overall economic cost associated with implantation and compared with estimates of the incremental health-sector cost of implantation. RESULTS: Data were provided by the families of 2858 children, 468 of whom had received a cochlear implant. Compared with the families of nonimplanted children, out-of-pocket expenditure was estimated to be significantly higher for families when children were implanted before the age of 5 yr and had used their implant for less than 2 yr, as was lost productivity when children had used their implants for less than 2 yr. Overall economic cost was estimated to be significantly higher for the families of implanted children who had used their implants for less than 2 yr. The cumulative economic cost was estimated to be 3355 euros for a family whose child was implanted at age 3 yr and 949 euros for a child implanted at age 6 yr. These costs correspond, at most, to 3% of the incremental health-sector costs of implantation. CONCLUSIONS: Compared with families of nonimplanted children, families of implanted children incur additional costs in the 2 yr after implantation. These costs are small in relation to the health-sector costs of providing implantation.

Hearing-impaired children in the United Kingdom, IV: cost-effectiveness of pediatric cochlear implantation.

OBJECTIVE: To estimate the cost-effectiveness of pediatric cochlear implantation by conducting a cost-utility analysis from a societal perspective. DESIGN: In a cross-sectional survey, the parents of a representative sample of hearing-impaired children assessed the health utility of their child using a revised version of the Health Utilities Index Mark III questionnaire. Linear regression was used to estimate the gain in health utility associated with implantation while controlling for eight potentially confounding variables: average (4-frequency, unaided, preoperative) hearing level (AHL), age at onset of hearing-impairment, age, gender, number of additional disabilities, parental occupational skill level, ethnicity, and parental hearing status. The gain in health utility was accumulated to estimate the number of quality-adjusted life years (QALYs) that would be gained from implantation over 15 yr and over a child's lifetime. The incremental societal cost of implantation, calculated in euros at 2001/2 levels, was estimated by summing the incremental costs of implantation that are incurred in the health sector, in the education sector, and by the child's family. The cost-effectiveness of cochlear implantation was estimated by calculating the incremental societal cost per QALY gained and was compared with an upper limit of acceptability of 50,000 euros per QALY. RESULTS: The parents of 403 implanted children, and 1863 nonimplanted children, completed the health utility questionnaire. Higher health utility was associated with a more favorable AHL, an older age at onset of hearing impairment, female gender, having fewer additional disabilities, having parents with a greater occupational skill level, white ethnicity, and implantation. The gain in health utility associated with implantation was estimated to be higher for children with a worse preoperative AHL and who were implanted when younger. Over 15 yr, for a child implanted at age 6 with a preoperative loss of 115 dB, 2.23 QALYs were estimated to be gained, compared with a mean incremental societal cost of 57,359 euros, yielding a mean cost per QALY of 25,629 euros. Cost-effectiveness was more favorable: (1) when estimated over a child's lifetime rather than 15 yr, (2) for children with a worse preoperative AHL, and (3) for children who were implanted when younger. CONCLUSIONS: The mean cost of gaining a QALY for the children in the present sample falls within acceptable limits. The strategy of giving highest priority for implantation to children with the greatest loss of hearing, and who are younger, maximizes benefit for a given cost.

An exploration of demographic bias in a questionnaire survey of hearing-impaired children: implications for comparisons of children with and without cochlear implants.

OBJECTIVES: Responders to questionnaire surveys, who are self-selecting, are generally accepted to be unrepresentative of the total available population, at least in demographic terms. Since demographic and other variables are known to be predictive of outcome, it is important to understand the extent of that unrepresentativeness when using survey data to report comparisons of outcome. This paper aims (i) to evaluate the extent to which a sample of hearing-impaired children surveyed by postal questionnaire was representative of the population of hearing-impaired children in the United Kingdom (UK), and (ii) to identify demographic differences between children with and without cochlear implants. METHODS: Data from a previously reported total ascertainment of hearing-impaired children in the UK which identified 17,160 with permanent bilateral hearing impairment >40 dB HL were compared with data collected by postal questionnaire for a sample of 3224 children, including 527 with cochlear implants. RESULTS: The sampled children were similar to the ascertained population in gender, age at onset of hearing impairment, and number of additional disabilities, but came from more recent birth cohorts and from more affluent families. Compared with profoundly impaired non-implanted children, implanted children had greater degrees of hearing loss, fewer additional disabilities, a later age of onset, were younger, came from more affluent families, were more likely to use spoken language at home, and to be taught using spoken language only. CONCLUSIONS: Comparisons of outcomes and generalisation of results require adjustment for relevant variables to avoid confounding estimates of the effectiveness of interventions including cochlear implantation.

Hearing-impaired children in the United Kingdom, II: Cochlear implantation and the cost of compulsory education.

OBJECTIVE: The objective of this study was to estimate the impact of cochlear implantation on the cost of compulsory education of hearing-impaired children in the United Kingdom. STUDY DESIGN: In a cross-sectional survey, teachers were asked to report the school placement of, and amount of support provided to, a representative sample of hearing-impaired children. Costs of school placement were obtained from published sources. Costs of support were calculated from a survey of 11 special education services. The annual education cost (in euros at 2001/2002 levels) of each child was calculated by summing the placement and support costs. Linear regression analyses calculated the association between annual education cost and possession of an implant while controlling nine other variables: average (unaided, preoperative) hearing level (AHL), age at onset of hearing impairment, age, gender, the number of additional disabilities, parental occupational skill level, ethnicity, parental hearing status, and academic achievement. RESULTS: Data were received for 2241 children, 383 of whom had cochlear implants. Mean annual education cost ranged from 15,745 euros for children with moderate hearing impairments to 30,071 euros for nonimplanted children with profound hearing impairments and was 28,058 euros for implanted children. A lower annual education cost was associated with a more favorable AHL, a later age at the onset of hearing impairment, female gender, a younger age, fewer additional disabilities, and a higher level of academic achievement. When these variables were controlled, costs were lower on average for implanted compared with nonimplanted children for the subset of children whose AHLs exceeded 111 dB. At the mean AHL of the implanted children (115 dB), implantation was associated with a reduction of 3105 euros (95% confidence interval, 1105 euros to 5106 euros) in annual education costs. CONCLUSIONS: Pediatric cochlear implantation is sufficiently effective to influence resource-allocation decisions in the education sector. The health-service cost of implantation is partly offset by savings in the cost of education. These savings occur without detriment to academic achievements.

Hearing-impaired children in the United Kingdom, I: Auditory performance, communication skills, educational achievements, quality of life, and cochlear implantation.

OBJECTIVES: The objectives of this study were to identify variables that are associated with differences in outcome among hearing-impaired children and to control those variables while assessing the impact of cochlear implantation. STUDY DESIGN: In a cross-sectional study, the parents and teachers of a representative sample of hearing-impaired children were invited to complete questionnaires about children's auditory performance, spoken communication skills, educational achievements, and quality of life. Multiple regression was used to measure the strength of association between these outcomes and variables related to the child (average hearing level, age at onset of hearing impairment, age, gender, number of additional disabilities), the family (parental occupational skill level, ethnicity, and parental hearing status), and cochlear implantation. RESULTS: Questionnaires were returned by the parents of 2858 children, 468 of whom had received a cochlear implant, and by the teachers of 2241 children, 383 of whom had received an implant. Across all domains, reported outcomes were better for children with fewer disabilities in addition to impaired hearing. Across most domains, reported outcomes were better for children who were older, female, with a more favorable average hearing level, with a higher parental occupational skill level, and with an onset of hearing-impairment after 3 years. When these variables were controlled, cochlear implantation was consistently associated with advantages in auditory performance and spoken communication skills, but less consistently associated with advantages in educational achievements and quality of life. Significant associations were found most commonly for children who were younger than 5 years when implanted, and had used implants for more than 4 years. These children, whose mean (preoperative, unaided) average hearing level was 118 dB, were reported to perform at the same level as nonimplanted children with average hearing levels in the range from 80 dB to 104 dB, depending on the outcome measure. CONCLUSIONS: When rigorous statistical control is exercised in comparing implanted and nonimplanted children, pediatric cochlear implantation is associated with reported improvements both in spoken communication skills and in some aspects of educational achievements and quality of life, provided that children receive implants before 5 years of age.

Face processing and familiarity: evidence from eye-movement data.

How is information extracted from familiar and unfamiliar faces? Three experiments, in which eye-movement measures were used, examined whether there was differential sampling of the internal face region according to familiarity. Experiment 1 used a face familiarity task and found that whilst the majority of fixations fell within the internal region, there were no differences in the sampling of this region according to familiarity. Experiment 2 replicated these findings, using a standard recognition memory paradigm. The third experiment employed a matching task, and once again found that the majority of fixations fell within the internal region. Additionally, this experiment found that there was more sampling of the internal region when faces were familiar compared with when they were unfamiliar. The use of eye fixation measures affirms the importance of internal facial features in the recognition of familiar faces compared with unfamiliar faces, but only when viewers compare pairs of faces.