Audiovisual Speech Perception Research Articles

The impact of visual information in speech perception for individuals with hearing loss: a mini review.

This review examines how visual information enhances speech perception in individuals with hearing loss, focusing on the impact of age, linguistic stimuli, and specific hearing loss factors on the effectiveness of audiovisual (AV) integration. While existing studies offer varied and sometimes conflicting findings regarding the use of visual cues, our analysis shows that these key factors can distinctly shape AV speech perception outcomes. For instance, younger individuals and those who receive early intervention tend to benefit more from visual cues, particularly when linguistic complexity is lower. Additionally, languages with dense phoneme spaces demonstrate a higher dependency on visual information, underscoring the importance of tailoring rehabilitation strategies to specific linguistic contexts. By considering these influences, we highlight areas where understanding is still developing and suggest how personalized rehabilitation strategies and supportive systems could be tailored to better meet individual needs. Furthermore, this review brings attention to important aspects that warrant further investigation, aiming to refine theoretical models and contribute to more effective, customized approaches to hearing rehabilitation.

Audiovisual speech perception of multilingual learners of Japanese

ABSTRACT Due to the complex nature of languages and the way they are used, it is often difficult to research multilinguals because of the considerable variation in the ways their spoken languages may impact their perceptions. For this reason, foreign language education research has largely been focused on English L2 speakers, overlooking how different languages might impact perception in multilingual speakers. Focusing on Japanese as a Second Language (JSL) learners, this research investigated how multilinguals responded to audiovisual cues in Japanese and English. Utilising web-based eye-tracking technology facilitated by WebGazer.js. Participants were asked to complete a novel phonetic distinction task while their gaze behaviour was measured. Contrary to initial theoretical expectations, the findings did not reveal significant mediation by gaze behaviour on the relationship between multilingualism and task performance. However, the study found that when looking at the duration of fixation on the mouth, there's a significant difference between native English speakers and native speakers of Asian languages when listening to English or Japanese. These findings indicate that further research that explores the nuances of gaze behaviour among multilingual learners of non-English languages (such as Japanese) is necessary.

Importance of Visual Support Through Lipreading in the Identification of Words in Spanish Language.

We sought to examine the contribution of visual cues, such as lipreading, in the identification of familiar (words) and unfamiliar (phonemes) words in terms of percent accuracy. For that purpose, in this retrospective study, we presented lists of words and phonemes (adult female healthy voice) in auditory (A) and audiovisual (AV) modalities to 65 Spanish normal-hearing male and female listeners classified in four age groups. Our results showed a remarkable benefit of AV information in word and phoneme recognition. Regarding gender, women exhibited better performance than men in both A and AV modalities, although we only found significant differences for words but not for phonemes. Concerning age, significant differences were detected in word recognition in the A modality between the youngest (18-29 years old) and oldest (⩾50 years old) groups only. We conclude visual information enhances word and phoneme recognition and women are more influenced by visual signals than men in AV speech perception. On the contrary, it seems that, overall, age is not a limiting factor for word recognition, with no significant differences observed in the AV modality.

Evidence for a Causal Dissociation of the McGurk Effect and Congruent Audiovisual Speech Perception via TMS to the Left pSTS.

Congruent visual speech improves speech perception accuracy, particularly in noisy environments. Conversely, mismatched visual speech can alter what is heard, leading to an illusory percept that differs from the auditory and visual components, known as the McGurk effect. While prior transcranial magnetic stimulation (TMS) and neuroimaging studies have identified the left posterior superior temporal sulcus (pSTS) as a causal region involved in the generation of the McGurk effect, it remains unclear whether this region is critical only for this illusion or also for the more general benefits of congruent visual speech (e.g., increased accuracy and faster reaction times). Indeed, recent correlative research suggests that the benefits of congruent visual speech and the McGurk effect rely on largely independent mechanisms. To better understand how these different features of audiovisual integration are causally generated by the left pSTS, we used single-pulse TMS to temporarily disrupt processing within this region while subjects were presented with either congruent or incongruent (McGurk) audiovisual combinations. Consistent with past research, we observed that TMS to the left pSTS reduced the strength of the McGurk effect. Importantly, however, left pSTS stimulation had no effect on the positive benefits of congruent audiovisual speech (increased accuracy and faster reaction times), demonstrating a causal dissociation between the two processes. Our results are consistent with models proposing that the pSTS is but one of multiple critical areas supporting audiovisual speech interactions. Moreover, these data add to a growing body of evidence suggesting that the McGurk effect is an imperfect surrogate measure for more general and ecologically valid audiovisual speech behaviors.

Audiovisual Speech Perception Benefits are Stable from Preschool through Adolescence.

The ability to leverage visual cues in speech perception- especially in noisy backgrounds- is well established from infancy to adulthood. Yet, the developmental trajectory of audiovisual benefits stays a topic of debate. The inconsistency in findings can be attributed to relatively small sample sizes or tasks that are not appropriate for given age groups. We designed an audiovisual speech perception task that was cognitively and linguistically age-appropriate from preschool to adolescence and recruited a large sample ( N = 161) of children (age 4-15). We found that even the youngest children show reliable speech perception benefits when provided with visual cues and that these benefits are consistent throughout development when auditory and visual signals match. Individual variability is explained by how the child experiences their speech-in-noise performance rather than the quality of the signal itself. This underscores the importance of visual speech for young children who are regularly in noisy environments like classrooms and playgrounds.

Audiovisual perception of interrupted speech by nonnative listeners.

The purpose of the present study was to examine the influence of visual cues in audiovisual perception of interrupted speech by nonnative English listeners and to identify the role of working memory, long-term memory retrieval, and vocabulary knowledge in audiovisual perception by nonnative listeners. The participants included 31 Mandarin-speaking English learners between 19 and 41 years of age. The perceptual stimuli were noise-filled periodically interrupted AzBio and QuickSIN sentences with or without visual cues that showed a male speaker uttering the sentences. In addition to sentence recognition, the listeners completed a semantic fluency task, verbal (operation span) and visuospatial (symmetry span) working memory tasks, and two vocabulary knowledge tests (Vocabulary Level Test and Lexical Test for Advanced Learners of English). The results revealed significantly better speech recognition in the audio-visual condition than the audio-only condition, but the magnitude of visual benefit was substantially attenuated for sentences that had limited semantic context. The listeners' vocabulary size in English played a key role in the restoration of missing speech information and audiovisual integration in the perception of interrupted speech. Meanwhile, the listeners' verbal working memory capacity played an important role in audiovisual integration especially for the difficult stimuli with limited semantic context.

Audiovisual Perception of Lexical Stress: Beat Gestures and Articulatory Cues.

Human communication is inherently multimodal. Auditory speech, but also visual cues can be used to understand another talker. Most studies of audiovisual speech perception have focused on the perception of speech segments (i.e., speech sounds). However, less is known about the influence of visual information on the perception of suprasegmental aspects of speech like lexical stress. In two experiments, we investigated the influence of different visual cues (e.g., facial articulatory cues and beat gestures) on the audiovisual perception of lexical stress. We presented auditory lexical stress continua of disyllabic Dutch stress pairs together with videos of a speaker producing stress on the first or second syllable (e.g., articulating VOORnaam or voorNAAM). Moreover, we combined and fully crossed the face of the speaker producing lexical stress on either syllable with a gesturing body producing a beat gesture on either the first or second syllable. Results showed that people successfully used visual articulatory cues to stress in muted videos. However, in audiovisual conditions, we were not able to find an effect of visual articulatory cues. In contrast, we found that the temporal alignment of beat gestures with speech robustly influenced participants' perception of lexical stress. These results highlight the importance of considering suprasegmental aspects of language in multimodal contexts.

Using network science to examine audio-visual speech perception with a multi-layer graph.

To examine visual speech perception (i.e., lip-reading), we created a multi-layer network (the AV-net) that contained: (1) an auditory layer with nodes representing phonological word-forms and edges connecting words that were phonologically related, and (2) a visual layer with nodes representing the viseme representations of words and edges connecting viseme representations that differed by a single viseme (and additional edges to connect related nodes in the two layers). The results of several computer simulations (in which activation diffused across the network to simulate word identification) are reported and compared to the performance of human participants who identified the same words in a condition in which audio and visual information were both presented (Simulation 1), in an audio-only presentation condition (Simulation 2), and a visual-only presentation condition (Simulation 3). Another simulation (Simulation 4) examined the influence of phonological information on visual speech perception by comparing performance in the multi-layer AV-net to a single-layer network that contained only a visual layer with nodes representing the viseme representations of words and edges connecting viseme representations that differed by a single viseme. We also report the results of several analyses of the errors made by human participants in the visual-only presentation condition. The results of our analyses have implications for future research and training of lip-reading, and for the development of automatic lip-reading devices and software for individuals with certain developmental or acquired disorders or for listeners with normal hearing in noisy conditions.

Perceptual uncertainty explains activation differences between audiovisual congruent speech and McGurk stimuli.

Face-to-face communication relies on the integration of acoustic speech signals with the corresponding facial articulations. In the McGurk illusion, an auditory /ba/ phoneme presented simultaneously with a facial articulation of a /ga/ (i.e., viseme), is typically fused into an illusory 'da' percept. Despite its widespread use as an index of audiovisual speech integration, critics argue that it arises from perceptual processes that differ categorically from natural speech recognition. Conversely, Bayesian theoretical frameworks suggest that both the illusory McGurk and the veridical audiovisual congruent speech percepts result from probabilistic inference based on noisy sensory signals. According to these models, the inter-sensory conflict in McGurk stimuli may only increase observers' perceptual uncertainty. This functional magnetic resonance imaging (fMRI) study presented participants (20 male and 24 female) with audiovisual congruent, McGurk (i.e., auditory /ba/ + visual /ga/), and incongruent (i.e., auditory /ga/ + visual /ba/) stimuli along with their unisensory counterparts in a syllable categorization task. Behaviorally, observers' response entropy was greater for McGurk compared to congruent audiovisual stimuli. At the neural level, McGurk stimuli increased activations in a widespread neural system, extending from the inferior frontal sulci (IFS) to the pre-supplementary motor area (pre-SMA) and insulae, typically involved in cognitive control processes. Crucially, in line with Bayesian theories these activation increases were fully accounted for by observers' perceptual uncertainty as measured by their response entropy. Our findings suggest that McGurk and congruent speech processing rely on shared neural mechanisms, thereby supporting the McGurk illusion as a valid measure of natural audiovisual speech perception.

Neural correlates of audiovisual narrative speech perception in children and adults on the autism spectrum: A functional magnetic resonance imaging study.

Autistic individuals show substantially reduced benefit from observing visual articulations during audiovisual speech perception, a multisensory integration deficit that is particularly relevant to social communication. This has mostly been studied using simple syllabic or word-level stimuli and it remains unclear how altered lower-level multisensory integration translates to the processing of more complex natural multisensory stimulus environments in autism. Here, functional neuroimaging was used to examine neural correlates of audiovisual gain (AV-gain) in 41 autistic individuals to those of 41 age-matched non-autistic controls when presented with a complex audiovisual narrative. Participants were presented with continuous narration of a story in auditory-alone, visual-alone, and both synchronous and asynchronous audiovisual speech conditions. We hypothesized that previously identified differences in audiovisual speech processing in autism would be characterized by activation differences in brain regions well known to be associated with audiovisual enhancement in neurotypicals. However, our results did not provide evidence for altered processing of auditory alone, visual alone, audiovisual conditions or AV- gain in regions associated with the respective task when comparing activation patterns between groups. Instead, we found that autistic individuals responded with higher activations in mostly frontal regions where the activation to the experimental conditions was below baseline (de-activations) in the control group. These frontal effects were observed in both unisensory and audiovisual conditions, suggesting that these altered activations were not specific to multisensory processing but reflective of more general mechanisms such as an altered disengagement of Default Mode Network processes during the observation of the language stimulus across conditions.

Audiovisual speech perception in noise in younger and older bilinguals.

Speech perception in noise becomes increasingly difficult with age. Similarly, bilinguals often have difficulty with speech perception in noise in their second language (L2) due to less developed language knowledge in L2. Little is known about older bilinguals, who experience age-related sensory and cognitive changes but have extensive L2 experience. Furthermore, while audiovisual (AV) speech cues and supportive sentence context facilitate speech perception in noise in native listeners, much less is known for bilingual listeners, particularly older bilinguals. This study investigated how much young (n = 30) and older (n = 31) French-English/English-French bilinguals benefit from AV speech cues and sentence context in their first (L1) and second language during speech perception in noise. Participants completed the task in L1 and L2. Importantly, the level of background noise was individually calibrated for each participant to equate performance during the baseline task. The results suggest that there were no age differences in overall performance during the speech perception in noise task. However, older adults showed smaller language effects and smaller modality effects (i.e., comparing auditory-only speech perception to audiovisual speech perception) compared to younger adults. Furthermore, both young and older bilinguals benefited from AV speech cues and sentence context in both of their languages. However, during L2 speech perception in noise, visual speech cues were particularly important for young adults. In contrast, older adults show equal benefit from visual speech cues in L1 and L2. Taken together, these findings extend current models of AV speech perception to a second language in both younger and older adults. Furthermore, the findings suggest that bilinguals are likely to benefit from visual speech cues and supportive sentence context, although this benefit may differ slightly between younger and older bilinguals. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Supplemental Material for Audiovisual Speech Perception in Noise in Younger and Older Bilinguals

Supplemental Material for Audiovisual Speech Perception in Noise in Younger and Older Bilinguals

The development of audiovisual speech perception in Mandarin-speaking children: Evidence from the McGurk paradigm.

The developmental trajectory of audiovisual speech perception in Mandarin-speaking children remains understudied. This cross-sectional study in Mandarin-speaking 3- to 4-year-old, 5- to 6-year-old, 7- to 8-year-old children, and adults from Xiamen, China (n = 87, 44 males) investigated this issue using the McGurk paradigm with three levels of auditory noise. For the identification of congruent stimuli, 3- to 4-year-olds underperformed older groups whose performances were comparable. For the perception of the incongruent stimuli, a developmental shift was observed as 3- to 4-year-olds made significantly more audio-dominant but fewer audiovisual-integrated responses to incongruent stimuli than older groups. With increasing auditory noise, the difference between children and adults widened in identifying congruent stimuli but narrowed in perceiving incongruent ones. The findings regarding noise effects agree with the statistically optimal hypothesis.

Using the Listening2Faces App with Three Young Adults with Autism: A Feasibility Study

Abstract Objectives Listening2Faces (L2F) is a therapeutic, application-based training program designed to improve audiovisual speech perception for persons with communication disorders. The purpose of this research was to investigate the feasibility of using the L2F application with young adults with autism and complex communication needs. Methods Three young adults with autism and complex communication needs completed baseline assessments and participated in training sessions within the L2F application. Behavioral supports, including the use of cognitive picture rehearsal, were used to support engagement with the L2F application. Descriptive statistics were used to provide (1) an overview of the level of participation in L2F application with the use of behavioral supports and (2) general performance on L2F application for each participant. Results All three participants completed the initial auditory noise assessment (ANA) as well as 8 or more levels of the L2F application with varying accuracy levels. One participant completed the entire L2F program successfully. Several behavioral supports were used to facilitate participation; however, each individual demonstrated varied levels of engagement with the application. Conclusions The L2F application may be a viable intervention tool to support audiovisual speech perception in persons with complex communication needs within a school-based setting. A review of behavioral supports and possible beneficial modifications to the L2F application for persons with complex communication needs are discussed.

Abnormal connectivity and activation during audiovisual speech perception in schizophrenia.

The unconscious integration of vocal and facial cues during speech perception facilitates face-to-face communication. Recent studies have provided substantial behavioural evidence concerning impairments in audiovisual (AV) speech perception in schizophrenia. However, the specific neurophysiological mechanism underlying these deficits remains unknown. Here, we investigated activities and connectivities centered on the auditory cortex during AV speech perception in schizophrenia. Using magnetoencephalography, we recorded and analysed event-related fields in response to auditory (A: voice), visual (V: face) and AV (voice-face) stimuli in 23 schizophrenia patients (13 males) and 22 healthy controls (13 males). The functional connectivity associated with the subadditive response to AV stimulus (i.e., [AV] < [A] + [V]) was also compared between the two groups. Within the healthy control group, [AV] activity was smaller than the sum of [A] and [V] at latencies of approximately 100 ms in the posterior ramus of the lateral sulcus in only the left hemisphere, demonstrating a subadditive N1m effect. Conversely, the schizophrenia group did not show such a subadditive response. Furthermore, weaker functional connectivity from the posterior ramus of the lateral sulcus of the left hemisphere to the fusiform gyrus of the right hemisphere was observed in schizophrenia. Notably, this weakened connectivity was associated with the severity of negative symptoms. These results demonstrate abnormalities in connectivity between speech- and face-related cortical areas in schizophrenia. This aberrant subadditive response and connectivity deficits for integrating speech and facial information may be the neural basis of social communication dysfunctions in schizophrenia.

Exploring audiovisual speech perception in monolingual and bilingual children in Uzbekistan

This study aimed to investigate the development of audiovisual speech perception in monolingual Uzbek-speaking and bilingual Uzbek–Russian-speaking children, focusing on the impact of language experience on audiovisual speech perception and the role of visual phonetic (i.e., mouth movements corresponding to phonetic/lexical information) and temporal (i.e., timing of speech signals) cues. A total of 321 children aged 4 to 10 years in Tashkent, Uzbekistan, discriminated /ba/ and /da/ syllables across three conditions: auditory-only, audiovisual phonetic (i.e., sound accompanied by mouth movements), and audiovisual temporal (i.e., sound onset/offset accompanied by mouth opening/closing). Effects of modality (audiovisual phonetic, audiovisual temporal, or audio-only cues), age, group (monolingual or bilingual), and their interactions were tested using a Bayesian regression model. Overall, older participants performed better than younger participants. Participants performed better in the audiovisual phonetic modality compared with the auditory modality. However, no significant difference between monolingual and bilingual children was observed across all modalities. This finding stands in contrast to earlier studies. We attribute the contrasting findings of our study and the existing literature to the cross-linguistic similarity of the language pairs involved. When the languages spoken by bilinguals exhibit substantial linguistic similarity, there may be an increased necessity to disambiguate speech signals, leading to a greater reliance on audiovisual cues. The limited phonological similarity between Uzbek and Russian might have minimized bilinguals’ need to rely on visual speech cues, contributing to the lack of group differences in our study.

The effect of face orientation on audiovisual speech integration in infancy: An electrophysiological study.

Humans pay special attention to faces and speech from birth, but the interplay of developmental processes leading to specialization is poorly understood. We investigated the effects of face orientation on audiovisual (AV) speech perception in two age groups of infants (younger: 5- to 6.5-month-olds; older: 9- to 10.5-month-olds) and adults. We recorded event-related potentials (ERP)in response to videos of upright and inverted faces producing /ba/ articulation dubbed with auditory syllables that were either matching /ba/ or mismatching /ga/ the mouth movement. We observed an increase in the amplitude of audiovisual mismatch response (AVMMR) to incongruent visual /ba/-auditory /ga/ syllable in comparison to other stimuli in younger infants, while the older group of infants did not show a similar response.AV mismatch response to inverted visual /ba/-auditory /ga/ stimulus relative to congruent stimuli was also detected in the right frontal areas in the younger group and the left and right frontal areas in adults. We show that face configuration affects the neural response to AV mismatch differently across all age groups. The novel finding of the AVMMR in response to inverted incongruent AV speech may potentially imply the featural face processing in younger infants and adults when processing inverted faces articulating incongruent speech. The lack of visible differential responses to upright and inverted incongruent stimuli obtained in the older group of infants suggests a likely functional cortical reorganization in the processing of AV speech.

The influence of temporal (a)synchrony and linguistic complexity on audiovisual speech perception

Audiovisual (AV) cues often lead to improved speech understanding, especially when the auditory input is impoverished (e.g., in background noise, for people with hearing loss). This AV improvement occurs when both the auditory and visual information can be integrated together effectively (e.g., through temporal synchrony). However, whether the complexity of speech signals influences this integrated percept and how this contributes to speech understanding is still unknown. This study investigates whether individual differences in perception of temporal synchrony of the auditory and visual speech signal explain individual variability in AV speech recognition, and whether this differs across different levels of linguistic processing. By implementing five different levels of linguistic complexity (i.e., varying phoneme-viseme connections, vocabulary knowledge and/or linguistic context) and introducing temporal asynchrony in a remote task with English speaking adults we ask the following questions: (1) Is temporal synchrony needed to observe AV speech perception benefits? (2) Does this vary by linguistic level? (3) Does linguistic complexity influence synchrony perception? (4) And does synchrony perception explain individual variability in AV speech perception? These findings add value in deciding how AV synchronization should be balanced in hearing aid designs as well as in augmented / virtual reality devices.

A representation of abstract linguistic categories in the visual system underlies successful lipreading

There is considerable debate over how visual speech is processed in the absence of sound and whether neural activity supporting lipreading occurs in visual brain areas. Much of the ambiguity stems from a lack of behavioral grounding and neurophysiological analyses that cannot disentangle high-level linguistic and phonetic/energetic contributions from visual speech. To address this, we recorded EEG from human observers as they watched silent videos, half of which were novel and half of which were previously rehearsed with the accompanying audio. We modeled how the EEG responses to novel and rehearsed silent speech reflected the processing of low-level visual features (motion, lip movements) and a higher-level categorical representation of linguistic units, known as visemes. The ability of these visemes to account for the EEG – beyond the motion and lip movements – was significantly enhanced for rehearsed videos in a way that correlated with participants’ trial-by-trial ability to lipread that speech. Source localization of viseme processing showed clear contributions from visual cortex, with no strong evidence for the involvement of auditory areas. We interpret this as support for the idea that the visual system produces its own specialized representation of speech that is (1) well-described by categorical linguistic features, (2) dissociable from lip movements, and (3) predictive of lipreading ability. We also suggest a reinterpretation of previous findings of auditory cortical activation during silent speech that is consistent with hierarchical accounts of visual and audiovisual speech perception.

Neural oscillations reflect the individual differences in the temporal perception of audiovisual speech.

Multisensory integration occurs within a limited time interval between multimodal stimuli. Multisensory temporal perception varies widely among individuals and involves perceptual synchrony and temporal sensitivity processes. Previous studies explored the neural mechanisms of individual differences for beep-flash stimuli, whereas there was no study for speech. In this study, 28 subjects (16 male) performed an audiovisual speech/ba/simultaneity judgment task while recording their electroencephalography. We examined the relationship between prestimulus neural oscillations (i.e. the pre-pronunciation movement-related oscillations) and temporal perception. The perceptual synchrony was quantified using the Point of Subjective Simultaneity and temporal sensitivity using the Temporal Binding Window. Our results revealed dissociated neural mechanisms for individual differences in Temporal Binding Window and Point of Subjective Simultaneity. The frontocentral delta power, reflecting top-down attention control, is positively related to the magnitude of individual auditory leading Temporal Binding Windows (auditory Temporal Binding Windows; LTBWs), whereas the parieto-occipital theta power, indexing bottom-up visual temporal attention specific to speech, is negatively associated with the magnitude of individual visual leading Temporal Binding Windows (visual Temporal Binding Windows; RTBWs). In addition, increased left frontal and bilateral temporoparietal occipital alpha power, reflecting general attentional states, is associated with increased Points of Subjective Simultaneity. Strengthening attention abilities might improve the audiovisual temporal perception of speech and further impact speech integration.