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

Previous research (e.g. McGurk and 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 and Soto-Faraco, 2011). We hypothesised 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

Children with SLI can exhibit reduced attention to a talker's mouth

It has been demonstrated that children with specific language impairment (SLI) show difficulties not only with auditory but also with audiovisual speech perception. The goal of this study was to assess whether children with SLI might show reduced attention to the talker's mouth compared to their typically developing (TD) peers. An additional aim was to determine whether the pattern of attention to a talking face would be related to a specific subtype of SLI. We used an eye-tracker methodology and presented a video of a talker speaking the children's native language. Results revealed that children with SLI paid significantly less attention to the mouth than the TD children. More specifically, it was also observed that children with a phonological-syntactic deficit looked less to the mouth as compared to the children with a lexical-syntactic deficit

How visual cues to speech rate influence speech perception

Spoken words are highly variable and therefore listeners interpret speech sounds relative to the surrounding acoustic context, such as the speech rate of a preceding sentence. For instance, a vowel midway between short /ɑ/ and long /a:/ in Dutch is perceived as short /ɑ/ in the context of preceding slow speech, but as long /a:/ if preceded by a fast context. Despite the well-established influence of visual articulatory cues on speech comprehension, it remains unclear whether visual cues to speech rate also influence subsequent spoken word recognition. In two ‘Go Fish’-like experiments, participants were presented with audio-only (auditory speech + fixation cross), visual-only (mute videos of talking head), and audiovisual (speech + videos) context sentences, followed by ambiguous target words containing vowels midway between short /ɑ/ and long /a:/. In Experiment 1, target words were always presented auditorily, without visual articulatory cues. Although the audio-only and audiovisual contexts induced a rate effect (i.e., more long /a:/ responses after fast contexts), the visual-only condition did not. When, in Experiment 2, target words were presented audiovisually, rate effects were observed in all three conditions, including visual-only. This suggests that visual cues to speech rate in a context sentence influence the perception of following visual target cues (e.g., duration of lip aperture), which at an audiovisual integration stage bias participants’ target categorization responses. These findings contribute to a better understanding of how what we see influences what we hear

Modulating fusion in the McGurk effect by binding processes and contextual noise

International audienceIn a series of experiments we showed that the McGurk effect may be modulated by context: applying incoherent auditory and visual material before an audiovisual target made of an audio "ba" and a video "ga" significantly decreases the McGurk effect. We interpreted this as showing the existence of an audiovisual "binding" stage controlling the fusion process. Incoherence would produce "unbinding" and result in decreasing the weight of the visual input in the fusion process. In this study, we further explore this binding stage around two experiments. Firstly we test the "rebinding" process, by presenting a short period of either coherent material or silence after the incoherent "unbinding" context. We show that coherence provides "rebinding", resulting in a recovery of the McGurk effect. In contrary, silence provides no rebinding and hence "freezes" the unbinding process, resulting in no recovery of the McGurk effect. Capitalizing on this result, in a second experiment including an incoherent unbinding context followed by a coherent rebinding context before the target, we add noise all over the contextual period, though not in the McGurk target. It appears that noise uniformly increases the rate of McGurk responses compared to the silent condition. This suggests that contextual noise increases the weight of the visual input in fusion, even if there is no noise within the target stimulus where fusion is applied. We conclude on the role of audiovisual coherence and noise in the binding process, in the framework of audiovisual speech scene analysis and the cocktail party effect

Effect of context, rebinding and noise, on audiovisual speech fusion

International audienceIn a previous set of experiments we showed that audio-visual fusion during the McGurk effect may be modulated by context. A short context (2 to 4 syllables) composed of incoherent auditory and visual material significantly decreases the McGurk effect. We interpreted this as showing the existence of an audiovisual "binding" stage controlling the fusion process, and we also showed the existence of a "rebinding" process when an incoherent material is followed by a short coherent material. In this work we evaluate the role of acoustic noise superimposed to the context and to the rebinding material. We use either a coherent or incoherent context, followed, if incoherent, by a variable amount of coherent "rebinding" material, with two conditions, either silent or with superimposed speech-shaped noise. The McGurk target is presented with no acoustic noise. We confirm the existence of unbinding (lower McGurk effect with incoherent context) and rebinding (the McGurk effect is recovered with coherent rebinding). Noise uniformly increases the rate of McGurk responses compared to the silent condition. We conclude on the role of audiovisual coherence and noise in the binding process, in the framework of audiovisual speech scene analysis and the cocktail party effect

Development of audiovisual comprehension skills in prelingually deaf children with cochlear implants

Objective: The present study investigated the development of audiovisual comprehension skills in prelingually deaf children who received cochlear implants. Design: We analyzed results obtained with the Common Phrases (Robbins et al., 1995) test of sentence comprehension from 80 prelingually deaf children with cochlear implants who were enrolled in a longitudinal study, from pre-implantation to 5 years after implantation. Results: The results revealed that prelingually deaf children with cochlear implants performed better under audiovisual (AV) presentation compared with auditory-alone (A-alone) or visual-alone (V-alone) conditions. AV sentence comprehension skills were found to be strongly correlated with several clinical outcome measures of speech perception, speech intelligibility, and language. Finally, pre-implantation V-alone performance on the Common Phrases test was strongly correlated with 3-year postimplantation performance on clinical outcome measures of speech perception, speech intelligibility, and language skills. Conclusions: The results suggest that lipreading skills and AV speech perception reflect a common source of variance associated with the development of phonological processing skills that is shared among a wide range of speech and language outcome measures

Audiovisual temporal correspondence modulates human multisensory superior temporal sulcus plus primary sensory cortices

The brain should integrate related but not unrelated information from different senses. Temporal patterning of inputs to different modalities may provide critical information about whether those inputs are related or not. We studied effects of temporal correspondence between auditory and visual streams on human brain activity with functional magnetic resonance imaging ( fMRI). Streams of visual flashes with irregularly jittered, arrhythmic timing could appear on right or left, with or without a stream of auditory tones that coincided perfectly when present ( highly unlikely by chance), were noncoincident with vision ( different erratic, arrhythmic pattern with same temporal statistics), or an auditory stream appeared alone. fMRI revealed blood oxygenation level-dependent ( BOLD) increases in multisensory superior temporal sulcus (mSTS), contralateral to a visual stream when coincident with an auditory stream, and BOLD decreases for noncoincidence relative to unisensory baselines. Contralateral primary visual cortex and auditory cortex were also affected by audiovisual temporal correspondence or noncorrespondence, as confirmed in individuals. Connectivity analyses indicated enhanced influence from mSTS on primary sensory areas, rather than vice versa, during audiovisual correspondence. Temporal correspondence between auditory and visual streams affects a network of both multisensory ( mSTS) and sensory-specific areas in humans, including even primary visual and auditory cortex, with stronger responses for corresponding and thus related audiovisual inputs

MUSIC TO OUR EYES: ASSESSING THE ROLE OF EXPERIENCE FOR MULTISENSORY INTEGRATION IN MUSIC PERCEPTION

Based on research on the “McGurk Effect” (McGurk & McDonald, 1976) in speech perception, some researchers (e.g. Liberman & Mattingly, 1985) have argued that humans uniquely interpret auditory and visual (motor) speech signals as a single intended audiovisual articulatory gesture, and that such multisensory integration is innate and specific to language. Our goal for the present study was to determine if a McGurk-like Effect holds true for music perception as well, as a domain for which innateness and experience can be disentangled more easily than in language. We sought to investigate the effects of visual musical information on auditory music perception and judgment, the impact of music experience on such audiovisual integration, and the possible role of eye gaze patterns as a potential mediator for music experience and the extent of visual influence on auditory judgments. 108 participants (ages 18-40) completed a questionnaire and melody/rhythm perception tasks to determine music experience and abilities, and then completed speech and musical McGurk tasks. Stimuli were recorded from five sounds produced by a speaker or musician (cellist and trombonist) that ranged incrementally along a continuum from one type to another (e.g. non-vibrato to strong vibrato). In the audiovisual condition, these sounds were paired with videos of the speaker/performer producing one type of sound or another (representing either end of the continuum) such that the audio and video matched or mismatched to varying degrees. Participants indicated, on a 100-point scale, the extent to which the auditory presentation represents one end of the continuum or the other. Auditory judgments for each sound were then compared based on their visual pairings to determine the impact of visual cues on auditory judgments. Additionally, several types of music experience were evaluated as potential predictors of the degree of influence visual stimuli had on auditory judgments. Finally, eye gaze patterns were measured in a different sample of 15 participants to assess relationships between music experience and eye gaze patterns, and eye gaze patterns and extent of visual on auditory judgments. Results indicated a reliable “musical McGurk Effect” in the context of cello vibrato sounds, but weaker overall effects for trombone vibrato sounds and cello pluck and bow sounds. Limited evidence was found to suggest that music experience impacts the extent to which individuals are influenced by visual stimuli when making auditory judgments. The support that was obtained, however, indicated the possibility for diminished visual influence on auditory judgments based on variables associated with music “production” experience. Potential relationships between music experience and eye-gaze patterns were identified. Implications for audiovisual integration in the context of speech and music perception are discussed, and future directions advised