Differences In Speech Perception Research Articles

The beneficial effect of transparent surgical masks on the communication of adults with hearing loss within clinical settings

Purpose: The study examined the benefits of transparent versus non-transparent surgical masks on the speech intelligibility in quiet of adult cochlear implant (CI) users, in conjunction with patient preferences and the acoustic effects of the different masks on the speech signal. Methods: Speech tracking test (STT) scores and acoustical characteristics were measured in quiet for live speech in three different conditions, without mask, with a non-transparent surgical mask and with a transparent surgical mask. Patients were asked about their experience with the face masks. The study sample consists of 30 patients using a cochlear implant. Results: We found a significant difference in speech perception among all conditions, with the speech tracking scores revealing a significant advantage when switching from the non-transparent surgical mask to the transparent one. The transparent surgical mask, although it does not transmit high frequencies effectively, seems to have minimal effect on speech comprehension in practice when lip movements are visible. This substantial benefit is further emphasized in the questionnaire, where 82% of the patients express a preference for the transparent surgical mask. Conclusion: The study highlights significant benefits for patients in speech intelligibility in quiet with the use of medically safe transparent facemasks. Transitioning from standard surgical masks to transparent masks demonstrates highly significant effectiveness and patient satisfaction for patients with hearing loss. This research strongly advocates for the implementation of transparent masks in broader hospital and perioperative settings.

Behavioral evidence of the modulation filterbank in an avian animal model of complex-sound perception

Behavioral detection of amplitude modulation (AM) can be adversely affected by competing AM “noise” present in the acoustic environment. Called AM masking, human studies suggest the existence of a modulation filterbank that separates sounds (signal from noise) based on differences in AM frequency. The modulation filterbank is an important theoretical advancement in hearing science because in addition to explaining AM masking, the model successfully predicts differences in speech perception across noisy listening environments with different AM statistics. Currently, there are no behavioral animal models of the modulation filterbank, presenting a serious impediment to understanding neural underpinnings. We trained budgerigars, a parakeet species, to detect AM frequencies from 64 to 400 Hz in the presence of narrowband AM maskers applied to a 2.8-kHz carrier signal. AM masker center frequencies spanned a >2 octave range centered on the target AM frequency. Behavioral AM sensitivity was evaluated with operant conditioning, a single-interval two-alternative discrimination task, and two-down one-up adaptive threshold tracking procedures. Budgerigar AM masking functions had a band-pass characteristic, consistent with the modulation filterbank and with human AM masking results for the same stimuli. To our knowledge, these are the first behaviorally estimated modulation filter shapes in a nonhuman species. [Funding: NIDCD R01-DC017519.]

Investigation of Cross-Language and Stimulus-Dependent Effects on the McGurk Effect with Finnish and Japanese Speakers and Listeners.

In the McGurk effect, perception of a spoken consonant is altered when an auditory (A) syllable is presented with an incongruent visual (V) syllable (e.g., A/pa/V/ka/ is often heard as /ka/ or /ta/). The McGurk effect provides a measure for visual influence on speech perception, becoming stronger the lower the proportion of auditory correct responses. Cross-language effects are studied to understand processing differences between one's own and foreign languages. Regarding the McGurk effect, it has sometimes been found to be stronger with foreign speakers. However, other studies have shown the opposite, or no difference between languages. Most studies have compared English with other languages. We investigated cross-language effects with native Finnish and Japanese speakers and listeners. Both groups of listeners had 49 participants. The stimuli (/ka/, /pa/, /ta/) were uttered by two female and male Finnish and Japanese speakers and presented in A, V and AV modality, including a McGurk stimulus A/pa/V/ka/. The McGurk effect was stronger with Japanese stimuli in both groups. Differences in speech perception were prominent between individual speakers but less so between native languages. Unisensory perception correlated with McGurk perception. These findings suggest that stimulus-dependent features contribute to the McGurk effect. This may have a stronger influence on syllable perception than cross-language factors.

Children with developmental dyslexia have equivalent audiovisual speech perception performance but their perceptual weights differ.

As reading is inherently a multisensory, audiovisual (AV) process where visual symbols (i.e., letters) are connected to speech sounds, the question has been raised whether individuals with reading difficulties, like children with developmental dyslexia (DD), have broader impairments in multisensory processing. This question has been posed before, yet it remains unanswered due to (a) the complexity and contentious etiology of DD along with (b) lack of consensus on developmentally appropriate AV processing tasks. We created an ecologically valid task for measuring multisensory AV processing by leveraging the natural phenomenon that speech perception improves when listeners are provided visual information from mouth movements (particularly when the auditory signal is degraded). We designed this AV processing task with low cognitive and linguistic demands such that children with and without DD would have equal unimodal (auditory and visual) performance. We then collected data in a group of 135 children (age 6.5-15) with an AV speech perception task to answer the following questions: (1) How do AV speech perception benefits manifest in children, with and without DD? (2) Do children all use the same perceptual weights to create AV speech perception benefits, and (3) what is the role of phonological processing in AV speech perception? We show that children with and without DD have equal AV speech perception benefits on this task, but that children with DD rely less on auditory processing in more difficult listening situations to create these benefits and weigh both incoming information streams differently. Lastly, any reported differences in speech perception in children with DD might be better explained by differences in phonological processing than differences in reading skills. RESEARCH HIGHLIGHTS: Children with versus without developmental dyslexia have equal audiovisual speech perception benefits, regardless of their phonological awareness or reading skills. Children with developmental dyslexia rely less on auditory performance to create audiovisual speech perception benefits. Individual differences in speech perception in children might be better explained by differences in phonological processing than differences in reading skills.

Neural and Behavioral Differences in Speech Perception for Children With Autism Spectrum Disorders Within an Audiovisual Context.

Reduced use of visible articulatory information on a speaker's face has been implicated as a possible contributor to language deficits in autism spectrum disorders (ASD). We employ an audiovisual (AV) phonemic restoration paradigm to measure behavioral performance (button press) and event-related potentials (ERPs) of visual speech perception in children with ASD and their neurotypical peers to assess potential neural substrates that contribute to group differences. Two sets of speech stimuli, /ba/-"/a/" ("/a/" was created from the /ba/ token by a reducing the initial consonant) and /ba/-/pa/, were presented within an auditory oddball paradigm to children aged 6-13 years with ASD (n = 17) and typical development (TD; n = 33) within two conditions. The AV condition contained a fully visible speaking face; the pixelated (PX) condition included a face, but the mouth and jaw were PX, removing all articulatory information. When articulatory features were present for the /ba/-"/a/" contrast, it was expected that the influence of the visual articulators would facilitate a phonemic restoration effect in which "/a/" would be perceived as /ba/. ERPs were recorded during the experiment while children were required to press a button for the deviant sound for both sets of speech contrasts within both conditions. Button press data revealed that TD children were more accurate in discriminating between /ba/-"/a/" and /ba/-/pa/ contrasts in the PX condition relative to the ASD group. ERPs in response to the /ba/-/pa/ contrast within both AV and PX conditions differed between children with ASD and TD children (earlier P300 responses for children with ASD). Children with ASD differ in the underlying neural mechanisms responsible for speech processing compared with TD peers within an AV context.

Behavioral and neurophysiological signatures of the modulation filterbank in an animal model

Fluctuations in the temporal envelope of sound, called amplitude modulation (AM), are an important information-bearing feature of many complex communication signals including speech. Human listeners show diminished sensitivity to AM signals in the presence of competing modulations of similar frequency, known as modulation masking. Modulation masking is not explainable by classic power-spectrum models, but instead suggests a “modulation filterbank” processing strategy that separates concurrent sounds (e.g., AM signals from noise) that have different modulation frequencies. The modulation filterbank is an exciting theoretical development because in addition to explaining modulation masking, the model predicts differences in speech perception across noise environments with different envelope statistics. However, the physiological underpinnings of the modulation filterbank remain uncertain due to limited nonhuman animal models. New behavioral and neurophysiological studies of the modulation filterbank are presented in budgerigars, a parakeet species with human-like behavioral sensitivity to many simple and complex sounds. Behavioral modulation-masking results show compelling evidence of the modulation filterbank in this animal model. Neural recordings from the inferior colliculus (midbrain level) further suggest that rate-based AM sensitivity can explain behavioral modulation-masking results. This new animal model of the modulation filterbank can be used to explore hearing mechanisms in real-world noisy listening environments.

Genetic Hearing Loss Affects Cochlear Processing.

The relationship between speech recognition and hereditary hearing loss is not straightforward. Underlying genetic defects might determine an impaired cochlear processing of sound. We obtained data from nine groups of patients with a specific type of genetic hearing loss. For each group, the affected cochlear site-of-lesion was determined based on previously published animal studies. Retrospectively obtained speech recognition scores in noise were related to several aspects of supra-threshold cochlear processing as assessed by psychophysical measurements. The differences in speech perception in noise between these patient groups could be explained by these factors and partially by the hypothesized affected structure of the cochlea, suggesting that speech recognition in noise was associated with a genetics-related malfunctioning of the cochlea. In particular, regression models indicate that loudness growth and spectral resolution best describe the cochlear distortions and are thus a good biomarker for speech understanding in noise.

Age Differences in Speech Perception in Noise and Sound Localization in Individuals With Subjective Normal Hearing.

Hearing loss in old age, which often goes untreated, has far-reaching consequences. Furthermore, reduction of cognitive abilities and dementia can also occur, which also affects quality of life. The aim of this study was to investigate the hearing performance of seniors without hearing complaints with respect to speech perception in noise and the ability to localize sounds. Results were tested for correlations with age and cognitive performance. The study included 40 subjects aged between 60 and 90 years (mean age: 69.3 years) with not self-reported hearing problems. The subjects were screened for dementia. Audiological tests included pure-tone audiometry and speech perception in two types of background noise (continuous and amplitude-modulated noise) which was either co-located or spatially separated (multi-source noise field, MSNF) from the target speech. Sound localization ability was assessed and hearing performance was self-evaluated by a questionnaire. Speech in noise and sound localization was compared with young normal hearing adults. Although considering themselves as hearing normal, 17 subjects had at least a mild hearing loss. There was a significant negative correlation between hearing loss and dementia screening (DemTect) score. Speech perception in noise decreased significantly with age. There were significant negative correlations between speech perception in noise and DemTect score for both spatial configurations. Mean SRTs obtained in the co-located noise condition with amplitude-modulated noise were on average 3.1 dB better than with continuous noise. This gap-listening effect was severely diminished compared to a younger normal hearing subject group. In continuous noise, spatial separation of speech and noise led to better SRTs compared to the co-located masker condition. SRTs in MSNF deteriorated in modulated noise compared to continuous noise by 2.6 dB. Highest impact of age was found for speech perception scores using noise stimuli with temporal modulation in binaural test conditions. Mean localization error was in the range of young adults. Mean amount of front/back confusions was 11.5% higher than for young adults. Speech perception tests in the presence of temporally modulated noise can serve as a screening method for early detection of hearing disorders in older adults. This allows for early prescription of hearing aids.

Speech Perception in Older Adults: An Interplay of Hearing, Cognition, and Learning?

Older adults with age-related hearing loss exhibit substantial individual differences in speech perception in adverse listening conditions. We propose that the ability to rapidly adapt to changes in the auditory environment (i.e., perceptual learning) is among the processes contributing to these individual differences, in addition to the cognitive and sensory processes that were explored in the past. Seventy older adults with age-related hearing loss participated in this study. We assessed the relative contribution of hearing acuity, cognitive factors (working memory, vocabulary, and selective attention), rapid perceptual learning of time-compressed speech, and hearing aid use to the perception of speech presented at a natural fast rate (fast speech), speech embedded in babble noise (speech in noise), and competing speech (dichotic listening). Speech perception was modeled as a function of the other variables. For fast speech, age [odds ratio (OR) = 0.79], hearing acuity (OR = 0.62), pre-learning (baseline) perception of time-compressed speech (OR = 1.47), and rapid perceptual learning (OR = 1.36) were all significant predictors. For speech in noise, only hearing and pre-learning perception of time-compressed speech were significant predictors (OR = 0.51 and OR = 1.53, respectively). Consistent with previous findings, the severity of hearing loss and auditory processing (as captured by pre-learning perception of time-compressed speech) was strong contributors to individual differences in fast speech and speech in noise perception. Furthermore, older adults with good rapid perceptual learning can use this capacity to partially offset the effects of age and hearing loss on the perception of speech presented at fast conversational rates. Our results highlight the potential contribution of dynamic processes to speech perception.

Distorted Tonotopy Severely Degrades Neural Representations of Connected Speech in Noise following Acoustic Trauma.

Listeners with sensorineural hearing loss (SNHL) struggle to understand speech, especially in noise, despite audibility compensation. These real-world suprathreshold deficits are hypothesized to arise from degraded frequency tuning and reduced temporal-coding precision; however, peripheral neurophysiological studies testing these hypotheses have been largely limited to in-quiet artificial vowels. Here, we measured single auditory-nerve-fiber responses to a connected speech sentence in noise from anesthetized male chinchillas with normal hearing (NH) or noise-induced hearing loss (NIHL). Our results demonstrated that temporal precision was not degraded following acoustic trauma, and furthermore that sharpness of cochlear frequency tuning was not the major factor affecting impaired peripheral coding of connected speech in noise. Rather, the loss of cochlear tonotopy, a hallmark of NH, contributed the most to both consonant-coding and vowel-coding degradations. Because distorted tonotopy varies in degree across etiologies (e.g., noise exposure, age), these results have important implications for understanding and treating individual differences in speech perception for people suffering from SNHL.SIGNIFICANCE STATEMENT Difficulty understanding speech in noise is the primary complaint in audiology clinics and can leave people with sensorineural hearing loss (SNHL) suffering from communication difficulties that affect their professional, social, and family lives, as well as their mental health. We measured single-neuron responses from a preclinical SNHL animal model to characterize salient neural-coding deficits for naturally spoken speech in noise. We found the major mechanism affecting neural coding was not a commonly assumed factor, but rather a disruption of tonotopicity, the systematic mapping of acoustic frequency to cochlear place that is a hallmark of normal hearing. Because the degree of distorted tonotopy varies across hearing-loss etiologies, these results have important implications for precision audiology approaches to diagnosis and treatment of SNHL.

Cutting Through the Noise: Noise-Induced Cochlear Synaptopathy and Individual Differences in Speech Understanding Among Listeners With Normal Audiograms.

Following a conversation in a crowded restaurant or at a lively party poses immense perceptual challenges for some individuals with normal hearing thresholds. A number of studies have investigated whether noise-induced cochlear synaptopathy (CS; damage to the synapses between cochlear hair cells and the auditory nerve following noise exposure that does not permanently elevate hearing thresholds) contributes to this difficulty. A few studies have observed correlations between proxies of noise-induced CS and speech perception in difficult listening conditions, but many have found no evidence of a relationship. To understand these mixed results, we reviewed previous studies that have examined noise-induced CS and performance on speech perception tasks in adverse listening conditions in adults with normal or near-normal hearing thresholds. Our review suggests that superficially similar speech perception paradigms used in previous investigations actually placed very different demands on sensory, perceptual, and cognitive processing. Speech perception tests that use low signal-to-noise ratios and maximize the importance of fine sensory details- specifically by using test stimuli for which lexical, syntactic, and semantic cues do not contribute to performance-are more likely to show a relationship to estimated CS levels. Thus, the current controversy as to whether or not noise-induced CS contributes to individual differences in speech perception under challenging listening conditions may be due in part to the fact that many of the speech perception tasks used in past studies are relatively insensitive to CS-induced deficits.

Comparison of sound perception using CIS and ACE sound coding strategies in cochlear implants

Objectives to study the effect of ACE and CIS sound coding strategies on sound perception in patients with the cochlear implants system produced by Cochlear Limited.
 Material and methods. The study included 50 patients taking the rehabilitation course in the Astrakhan branch of the National Medical Research Center for Otorhinolaryngology of the Federal Medico-Biological Agency over the past 5 years (from 2014 to 2019). The group of subjects included children over 7 years old and adults, whose success in rehabilitation made it possible to perform a full range of tests. The patients underwent tonal threshold audiometry and speech audiometry in a free sound field; the results obtained were registered in special MS Excel tables and further analysed using statistical methods.
 Results. There were no statistically significant differences in hearing thresholds on tonal audiometry when using the coding strategies ACE and CIS, however, differences in speech perception were observed on average by 4.2%. The patients experienced in using hearing aids reported improved speech recognition, with scores varying within 5%.
 Conclusion. Using a higher-resolution coding strategy can significantly improve speech recognition, while lower-resolution coding is beneficial for patients with digital hearing aid experience.

Cochlear Implantation in Pediatric Patients With Enlarged Vestibular Aqueduct: A Systematic Review

To describe cochlear implantation (CI) outcomes, with speech perception, auditory, language, and parent-reported auditory and speech behaviors, in children with an enlarged vestibular aqueduct (EVA) and incomplete partition type 2 (IP-II) and compare to control children without inner ear malformations (IEMs) and to determine cerebrospinal fluid gusher rates and effect on outcomes. Systematic review and meta-analysis. MEDLINE, Embase, Cochrane, and CINAHL databases were searched from inception to February 2020. Studies reporting relevant outcomes in children with EVA or EVA + IP-II and controls without IEMs undergoing CI were included. Mean differences in speech perception, auditory, and language scores between cases and controls were meta-analyzed. Gusher rates were determined by proportion meta-analyses. Of 214 identified articles, 42 met inclusion criteria, evaluating 775 cases and 2,191 controls. Of -cases, 578 (74.6%) had EVA and 197 (25.4%) had EVA + IP-II. Cases showed a significant improvement in speech perception, auditory and language performance, comparable to controls. Parent-reported auditory and speech production behaviors outcomes were positive among cases and comparable to controls. Pooled gusher proportions in EVA and EVA + IP-II cases were 27.7% (95% CI: 17.6-39.1) and 48.6% (95% CI: 28.6-69.0), respectively, with a proportion difference of 20.9% (95% CI: 11.0-30.1). Gusher occurrence did not impact speech perception or language outcomes. Outcomes in children with EVA or EVA + IP-II undergoing CI are favorable and largely comparable to outcomes in children with hearing loss undergoing CI without IEMs. Intraoperative gusher is more prevalent among children with EVA + IP-II as compared to iEVA. Gusher does not influence speech perception and language development outcomes. NA Laryngoscope, 132:1459-1472, 2022.

Assessment of speech perception in deaf or hard of hearing children who received auditory-verbal therapy with hearing aids or cochlear implants

ObjectivesTo reframe the criteria for pediatric cochlear implants (CIs) in Japan, we investigated monosyllabic and word speech perception at the time of school entry in deaf or hard of hearing (D/HH) children who underwent auditory-verbal therapy (AVT) with hearing aids (HAs) or CIs in early childhood. MethodsD/HH children who started AVT at Fujimidai Auditory Center for Hearing-Impaired Children before the age of 1 year and who underwent auditory assessment in the previous year of schooling (at the age of 5 or 6) from 2010 to 2020 were enrolled in this study. The results of hearing level tests with or without amplification and monosyllabic and word speech discrimination were assessed. ResultsThe children with profound hearing impairment (>90 dB HL) had worse speech perception than children with CIs. The children with severe hearing impairment (>70–90 dB HL) did not show any significant differences in speech perception compared with the children with CIs. The children with HAs with a wearing threshold <40 dB HL did not show any significant differences in speech perception from the children with CIs. ConclusionD/HH children with audiologic thresholds greater than 90 dB HL or aided thresholds greater than 40 dB HL should be considered for CIs to ensure development of appropriate listening and spoken language.

Individual differences in speech perception: Evidence for gradiency in the face of category-driven perceptual warping

In contrast to the long-running debates around universally categorical vs. gradient speech perception, we find individual differences in listeners' sensitivity to subtle acoustic differences between speech sounds (within and between phoneme categories). Here, we used an EEG measure of listeners' early perceptual encoding of a primary acoustic cue and found that categorical listeners showed stronger perceptual warping around the boundary, even as sensitivity to within-category differences was present across the board.

Individual Differences in Lexical Contributions to Speech Perception.

Purpose The extant literature suggests that individual differences in speech perception can be linked to broad receptive language phenotype. For example, a recent study found that individuals with a smaller receptive vocabulary showed diminished lexically guided perceptual learning compared to individuals with a larger receptive vocabulary. Here, we examined (a) whether such individual differences stem from variation in reliance on lexical information or variation in perceptual learning itself and (b) whether a relationship exists between lexical recruitment and lexically guided perceptual learning more broadly, as predicted by current models of lexically guided perceptual learning. Method In Experiment 1, adult participants (n = 70) completed measures of receptive and expressive language ability, lexical recruitment, and lexically guided perceptual learning. In Experiment 2, adult participants (n = 120) completed the same lexical recruitment and lexically guided perceptual learning tasks to provide a high-powered replication of the primary findings from Experiment 1. Results In Experiment 1, individuals with weaker receptive language ability showed increased lexical recruitment relative to individuals with higher receptive language ability; however, receptive language ability did not predict the magnitude of lexically guided perceptual learning. Moreover, the results of both experiments converged to show no evidence indicating a relationship between lexical recruitment and lexically guided perceptual learning. Conclusion The current findings suggest that (a) individuals with weaker language ability demonstrate increased reliance on lexical information for speech perception compared to those with stronger receptive language ability; (b) individuals with weaker language ability maintain an intact perceptual learning mechanism; and, (c) to the degree that the measures used here accurately capture individual differences in lexical recruitment and lexically guided perceptual learning, there is no graded relationship between these two constructs.

The roles of cognitive abilities and hearing acuity in older adults’ recognition of words taken from fast and spectrally reduced speech

AbstractPrevious literature has identified several cognitive abilities as predictors of individual differences in speech perception. Working memory was chief among them, but effects have also been found for processing speed. Most research has been conducted on speech in noise, but fast and unclear articulation also makes listening challenging, particularly for older listeners. As a first step toward specifying the cognitive mechanisms underlying spoken word recognition, we set up this study to determine which factors explain unique variation in word identification accuracy in fast speech, and the extent to which this was affected by further degradation of the speech signal. To that end, 105 older adults were tested on identification accuracy of fast words in unaltered and degraded conditions in which the speech stimuli were low-pass filtered. They were also tested on processing speed, memory, vocabulary knowledge, and hearing sensitivity. A structural equation analysis showed that only memory and hearing sensitivity explained unique variance in word recognition in both listening conditions. Working memory was more strongly associated with performance in the unfiltered than in the filtered condition. These results suggest that memory skills, rather than speed, facilitate the mapping of single words onto stored lexical representations, particularly in conditions of medium difficulty.

Brain aging and speech perception: Effects of background noise and talker variability

Speech perception can be challenging, especially for older adults. Despite the importance of speech perception in social interactions, the mechanisms underlying these difficulties remain unclear and treatment options are scarce. While several studies have suggested that decline within cortical auditory regions may be a hallmark of these difficulties, a growing number of studies have reported decline in regions beyond the auditory processing network, including regions involved in speech processing and executive control, suggesting a potentially diffuse underlying neural disruption, though no consensus exists regarding underlying dysfunctions. To address this issue, we conducted two experiments in which we investigated age differences in speech perception when background noise and talker variability are manipulated, two factors known to be detrimental to speech perception. In Experiment 1, we examined the relationship between speech perception, hearing and auditory attention in 88 healthy participants aged 19 to 87 years. In Experiment 2, we examined cortical thickness and BOLD signal using magnetic resonance imaging (MRI) and related these measures to speech perception performance using a simple mediation approach in 32 participants from Experiment 1. Our results show that, even after accounting for hearing thresholds and two measures of auditory attention, speech perception significantly declined with age. Age-related decline in speech perception in noise was associated with thinner cortex in auditory and speech processing regions (including the superior temporal cortex, ventral premotor cortex and inferior frontal gyrus) as well as in regions involved in executive control (including the dorsal anterior insula, the anterior cingulate cortex and medial frontal cortex). Further, our results show that speech perception performance was associated with reduced brain response in the right superior temporal cortex in older compared to younger adults, and to an increase in response to noise in older adults in the left anterior temporal cortex. Talker variability was not associated with different activation patterns in older compared to younger adults. Together, these results support the notion of a diffuse rather than a focal dysfunction underlying speech perception in noise difficulties in older adults.

Rapid Perceptual Learning and Individual Differences in Speech Perception: The Good, the Bad, and the Sad

ABSTRACT The function of rapid perceptual learning for speech in adult listeners is poorly understood. On the one hand, perceptual learning of speech results in rapid and long-lasting improvements in the perception of many types of distorted and degraded speech signals. On the other hand, this learning is highly specific to stimuli that were encountered during its acquisition. Therefore, it is unclear whether past perceptual learning could support future speech perception under ecological conditions. Here, we hypothesize that rapid perceptual learning is a resource that is recruited when new speech challenges are encountered and used to support perception under those specific conditions. We review three lines of evidence related to aspects of this hypothesis – about the specificity of learning, the general nature of associations between rapid perceptual learning and speech perception and rapid perceptual-learning in populations with poor perception under adverse conditions.

Contributions of acoustic and lexical cue weighting to individual differences in speech perception

Past research suggests that individuals with weaker receptive language show increased reliance on lexical information for speech perception relative to individuals with stronger receptive language, which may reflect a difference in how acoustic and lexical cues are weighted during online speech processing. Here we investigated whether this relationship is the consequence of removing natural correlations between acoustic and lexical cues in speech input, as in the specific stimulus distributions used in previous research. Two groups of adult participants completed measures of receptive and expressive language ability in addition to a measure of lexical recruitment (i.e., a phonetic identification task to measure the Ganong effect). In the high conflict group, the stimulus input distributions put acoustic and lexical cues in high competition; in the low conflict group, this competition was reduced. The results showed that (1) the Ganong effect was larger in the low compared to the high conflict condition, (2) the Ganong effect was larger for those with weaker compared to stronger receptive language, and (3) the relationship between the Ganong effect and receptive language was not mediated by conflict. These results demonstrate increased reliance on lexical information among those with weaker receptive language, suggesting that listeners with weaker language abilities down-weight acoustic cues and rely more heavily on lexical knowledge even when natural acoustic and lexical cue correlations are maintained in the input.