The Benefit of Bimodal Training in Voice Learning.

It is known that talkers can be recognized by listening to their specific vocal qualities-breathiness and fundamental frequencies. However, talker identification can also occur by focusing on the talkers' unique articulatory style, which is known to be available auditorily and visually and can be shared across modalities. Evidence shows that voices heard while seeing talkers' faces are later recognized better on their own compared to the voices heard alone. The present study investigated whether the facilitation of voice learning through facial cues relies on talker-specific articulatory or nonarticulatory facial information. Participants were initially trained to learn the voices of ten talkers presented either on their own or together with (a) an articulating face, (b) a static face, or (c) an isolated articulating mouth. Participants were then tested on recognizing the voices on their own regardless of their training modality. Consistent with previous research, voices learned with articulating faces were recognized better on their own compared to voices learned alone. However, isolated articulating mouths did not provide an advantage in learning the voices. The results demonstrated that learning voices while seeing faces resulted in better voice learning compared to the voices learned alone.

Semantic priming from McGurk words: Priming depends on perception.

The McGurk effect is an illusion in which visible articulations alter the perception of auditory speech (e.g., video 'da' dubbed with audio 'ba' may be heard as 'da'). To test the timing of the multisensory processes that underlie the McGurk effect, Ostrand et al. Cognition 151, 96-107, 2016 used incongruent stimuli, such as auditory 'bait' + visual 'date' as primes in a lexical decision task. These authors reported that the auditory word, but not the perceived (visual) word, induced semantic priming, suggesting that the auditory signal alone can provide the input for lexical access, before multisensory integration is complete. Here, we conceptually replicate the design of Ostrand et al. (2016), using different stimuli chosen to optimize the success of the McGurk illusion. In contrast to the results of Ostrand et al. (2016), we find that the perceived (i.e., visual) word of the incongruent stimulus usually induced semantic priming. We further find that the strength of this priming corresponded to the magnitude of the McGurk effect for each word combination. These findings suggest, in contrast to the findings of Ostrand et al. (2016), that lexical access makes use of integrated multisensory information which is perceived by the listener. These findings further suggest that which unimodal signal of a multisensory stimulus is used in lexical access is dependent on the perception of that stimulus.

Selective adaptation in speech: Measuring the effects of visual and lexical contexts.

Speech selective adaptation is a phenomenon in which repeated presentation of a speech stimulus alters subsequent phonetic categorization. Prior work has reported that lexical, but not multisensory, context influences selective adaptation. This dissociation suggests that lexical and multisensory contexts influence speech perception through separate and independent processes (see Samuel & Lieblich, 2014). However, this dissociation is based on results reported by different studies using different stimuli. This leaves open the possibility that the divergent effects of multisensory and lexical contexts on selective adaptation may be the result of idiosyncratic differences in the stimuli rather than separate perceptual processes. The present investigation used a single stimulus set to compare the selective adaptation produced by lexical and multisensory contexts. In contrast to the apparent dissociation in the literature, we find that multisensory information can in fact support selective adaptation. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Cross-modal transfer of talker-identity learning.

A speech signal carries information about meaning and about the talker conveying that meaning. It is now known that these two dimensions are related. There is evidence that gaining experience with a particular talker in one modality not only facilitates better phonetic perception in that modality, but also transfers across modalities to allow better phonetic perception in the other. This finding suggests that experience with a talker provides familiarity with some amodal properties of their articulation such that the experience can be shared across modalities. The present study investigates if experience with talker-specific articulatory information can also support cross-modal talker learning. In Experiment 1 we show that participants can learn to identify ten novel talkers from point-light and sinewave speech, expanding on prior work. Point-light and sinewave speech also supported similar talker identification accuracies, and similar patterns of talker confusions were found across stimulus types. Experiment 2 showed these stimuli could also support cross-modal talker matching, further expanding on prior work. Finally, in Experiment 3 we show that learning to identify talkers in one modality (visual-only point-light speech) facilitates learning of those same talkers in another modality (auditory-only sinewave speech). These results suggest that some of the information for talker identity takes a modality-independent form.

The role of speech fidelity in the irrelevant sound effect: Insights from noise-vocoded speech backgrounds.

The Irrelevant Sound Effect (ISE) is the finding that background sound impairs accuracy for visually presented serial recall tasks. Among various auditory backgrounds, speech typically acts as the strongest distractor. Based on the changing-state hypothesis, speech is a disruptive background because it is more complex than other nonspeech backgrounds. In the current study, we evaluate an alternative explanation by examining whether the speech-likeness of the background (speech fidelity) contributes, beyond signal complexity, to the ISE. We did this by using noise-vocoded speech as a background. In Experiment 1, we varied the complexity of the background by manipulating the number of vocoding channels. Results indicate that the ISE increases with the number of channels, suggesting that more complex signals produce greater ISEs. In Experiment 2, we varied complexity and speech fidelity independently. At each channel level, we selectively reversed a subset of channels to design a low-fidelity signal that was equated in overall complexity. Experiment 2 results indicated that speech-like noise-vocoded speech produces a larger ISE than selectively reversed noise-vocoded speech. Finally, in Experiment 3, we evaluated the locus of the speech-fidelity effect by assessing the distraction produced by these stimuli in a missing-item task. In this task, even though noise-vocoded speech disrupted task performance relative to silence, neither its complexity nor speech fidelity contributed to this effect. Together, these findings indicate a clear role for speech fidelity of the background beyond its changing-state quality and its attention capture potential.

Neural Mechanisms Underlying Cross-Modal Phonetic Encoding.

Audiovisual (AV) integration is essential for speech comprehension, especially in adverse listening situations. Divergent, but not mutually exclusive, theories have been proposed to explain the neural mechanisms underlying AV integration. One theory advocates that this process occurs via interactions between the auditory and visual cortices, as opposed to fusion of AV percepts in a multisensory integrator. Building upon this idea, we proposed that AV integration in spoken language reflects visually induced weighting of phonetic representations at the auditory cortex. EEG was recorded while male and female human subjects watched and listened to videos of a speaker uttering consonant vowel (CV) syllables /ba/ and /fa/, presented in Auditory-only, AV congruent or incongruent contexts. Subjects reported whether they heard /ba/ or /fa/. We hypothesized that vision alters phonetic encoding by dynamically weighting which phonetic representation in the auditory cortex is strengthened or weakened. That is, when subjects are presented with visual /fa/ and acoustic /ba/ and hear /fa/ (illusion-fa), the visual input strengthens the weighting of the phone /f/ representation. When subjects are presented with visual /ba/ and acoustic /fa/ and hear /ba/ (illusion-ba), the visual input weakens the weighting of the phone /f/ representation. Indeed, we found an enlarged N1 auditory evoked potential when subjects perceived illusion-ba, and a reduced N1 when they perceived illusion-fa, mirroring the N1 behavior for /ba/ and /fa/ in Auditory-only settings. These effects were especially pronounced in individuals with more robust illusory perception. These findings provide evidence that visual speech modifies phonetic encoding at the auditory cortex.SIGNIFICANCE STATEMENT The current study presents evidence that audiovisual integration in spoken language occurs when one modality (vision) acts on representations of a second modality (audition). Using the McGurk illusion, we show that visual context primes phonetic representations at the auditory cortex, altering the auditory percept, evidenced by changes in the N1 auditory evoked potential. This finding reinforces the theory that audiovisual integration occurs via visual networks influencing phonetic representations in the auditory cortex. We believe that this will lead to the generation of new hypotheses regarding cross-modal mapping, particularly whether it occurs via direct or indirect routes (e.g., via a multisensory mediator).

Influences of selective adaptation on perception of audiovisual speech.

Research suggests that selective adaptation in speech is a low-level process dependent on sensory-specific information shared between the adaptor and test-stimuli. However, previous research has only examined how adaptors shift perception of unimodal test stimuli, either auditory or visual. In the current series of experiments, we investigated whether adaptation to cross-sensory phonetic information can influence perception of integrated audio-visual phonetic information. We examined how selective adaptation to audio and visual adaptors shift perception of speech along an audiovisual test continuum. This test-continuum consisted of nine audio-/ba/-visual-/va/ stimuli, ranging in visual clarity of the mouth. When the mouth was clearly visible, perceivers "heard" the audio-visual stimulus as an integrated "va" percept 93.7% of the time (e.g., McGurk & MacDonald, 1976). As visibility of the mouth became less clear across the nine-item continuum, the audio-visual "va" percept weakened, resulting in a continuum ranging in audio-visual percepts from /va/ to /ba/. Perception of the test-stimuli was tested before and after adaptation. Changes in audiovisual speech perception were observed following adaptation to visual-/va/ and audiovisual-/va/, but not following adaptation to auditory-/va/, auditory-/ba/, or visual-/ba/. Adaptation modulates perception of integrated audio-visual speech by modulating the processing of sensory-specific information. The results suggest that auditory and visual speech information are not completely integrated at the level of selective adaptation.

Visibility of speech articulation enhances auditory phonetic convergence.

Talkers automatically imitate aspects of perceived speech, a phenomenon known as phonetic convergence. Talkers have previously been found to converge to auditory and visual speech information. Furthermore, talkers converge more to the speech of a conversational partner who is seen and heard, relative to one who is just heard (Dias & Rosenblum Perception, 40, 1457-1466, 2011). A question raised by this finding is what visual information facilitates the enhancement effect. In the following experiments, we investigated the possible contributions of visible speech articulation to visual enhancement of phonetic convergence within the noninteractive context of a shadowing task. In Experiment 1, we examined the influence of the visibility of a talker on phonetic convergence when shadowing auditory speech either in the clear or in low-level auditory noise. The results suggest that visual speech can compensate for convergence that is reduced by auditory noise masking. Experiment 2 further established the visibility of articulatory mouth movements as being important to the visual enhancement of phonetic convergence. Furthermore, the word frequency and phonological neighborhood density characteristics of the words shadowed were found to significantly predict phonetic convergence in both experiments. Consistent with previous findings (e.g., Goldinger Psychological Review, 105, 251-279, 1998), phonetic convergence was greater when shadowing low-frequency words. Convergence was also found to be greater for low-density words, contrasting with previous predictions of the effect of phonological neighborhood density on auditory phonetic convergence (e.g., Pardo, Jordan, Mallari, Scanlon, & Lewandowski Journal of Memory and Language, 69, 183-195, 2013). Implications of the results for a gestural account of phonetic convergence are discussed.

Experience with a talker can transfer across modalities to facilitate lipreading.

Rosenblum, Miller, and Sanchez (Psychological Science, 18, 392-396, 2007) found that subjects first trained to lip-read a particular talker were then better able to perceive the auditory speech of that same talker, as compared with that of a novel talker. This suggests that the talker experience a perceiver gains in one sensory modality can be transferred to another modality to make that speech easier to perceive. An experiment was conducted to examine whether this cross-sensory transfer of talker experience could occur (1) from auditory to lip-read speech, (2) with subjects not screened for adequate lipreading skill, (3) when both a familiar and an unfamiliar talker are presented during lipreading, and (4) for both old (presentation set) and new words. Subjects were first asked to identify a set of words from a talker. They were then asked to perform a lipreading task from two faces, one of which was of the same talker they heard in the first phase of the experiment. Results revealed that subjects who lip-read from the same talker they had heard performed better than those who lip-read a different talker, regardless of whether the words were old or new. These results add further evidence that learning of amodal talker information can facilitate speech perception across modalities and also suggest that this information is not restricted to previously heard words.

Is speech alignment to talkers or tasks?

Speech alignment, or the tendency of individuals to subtly imitate each other's speaking styles, is often assessed by comparing a subject's baseline and shadowed utterances to a model's utterances, often through perceptual ratings. These types of comparisons provide information about the occurrence of a change in subject's speech, but they do not indicate that this change is toward the specific shadowed model. In three experiments, we investigated whether alignment is specific to a shadowed model. Experiment 1 involved the classic baseline-to-shadowed comparison, to confirm that subjects did, in fact, sound more like their model when they shadowed, relative to any preexisting similarities between a subject and a model. Experiment 2 tested whether subjects' utterances sounded more similar to the model whom they had shadowed or to another, unshadowed model. In Experiment 3, we examined whether subjects' utterances sounded more similar to the model whom they had shadowed or to another subject who had shadowed a different model. The results of all experiments revealed that subjects sounded more similar to the model whom they had shadowed. This suggests that shadowing-based speech alignment is not just a change, but a change in the direction of the shadowed model, specifically.

Visual influences on interactive speech alignment.

Speech alignment describes the unconscious tendency to produce speech that shares characteristics with perceived speech (eg Goldinger, 1998 Psychological Review 105 251-279). In the present study we evaluated whether seeing a talker enhances alignment over just hearing a talker. Pairs of participants performed an interactive search task which required them to repeatedly utter a series of keywords. Half of the pairs performed the task while hearing each other, while the other half could see and hear each other. Alignment was assessed by naive judges rating the similarity of interlocutors' keywords recorded before, during, and after the interactive task. Results showed that interlocutors aligned more when able to see one another suggesting that visual information enhances speech alignment.

Alignment to visual speech information.

Speech alignment is the tendency for interlocutors to unconsciously imitate one another's speaking style. Alignment also occurs when a talker is asked to shadow recorded words (e.g., Shockley, Sabadini, & Fowler, 2004). In two experiments, we examined whether alignment could be induced with visual (lipread) speech and with auditory speech. In Experiment 1, we asked subjects to lipread and shadow out loud a model silently uttering words. The results indicate that shadowed utterances sounded more similar to the model's utterances than did subjects' nonshadowed read utterances. This suggests that speech alignment can be based on visual speech. In Experiment 2, we tested whether raters could perceive alignment across modalities. Raters were asked to judge the relative similarity between a model's visual (silent video) utterance and subjects' audio utterances. The subjects' shadowed utterances were again judged as more similar to the model's than were read utterances, suggesting that raters are sensitive to cross-modal similarity between aligned words.

Visual influences on alignment to voice onset time.

PURPOSE: Speech shadowing experiments were conducted to test whether alignment (inadvertent imitation) to voice onset time (VOT) can be influenced by visual speech information. METHOD: Experiment 1 examined whether alignment would occur to auditory /pa/ syllables manipulated to have 3 different VOTs. Nineteen female participants were asked to listen to 180 syllables over headphones and to say each syllable out loud quickly and clearly. In Experiment 2, visual speech tokens composed of a face articulating /pa/ syllables at 2 different rates were dubbed onto the audio /pa/ syllables of Experiment 1. Sixteen new female participants were asked to listen to and watch (over a video monitor) 180 syllables and to say each syllable out loud quickly and clearly. RESULTS: Results of Experiment 1 showed that the 3 VOTs of the audio /pa/ stimuli influenced the VOTs of the participants' produced syllables. Results of Experiment 2 revealed that both the visible syllable rate and audio VOT of the audiovisual /pa/ stimuli influenced the VOTs of the participants' produced syllables. CONCLUSION: These results show that, like auditory speech, visual speech information can induce speech alignment to a phonetically relevant property of an utterance.

Speech Perception as a Multimodal Phenomenon.

Speech perception is inherently multimodal. Visual speech (lip-reading) information is used by all perceivers and readily integrates with auditory speech. Imaging research suggests that the brain treats auditory and visual speech similarly. These findings have led some researchers to consider that speech perception works by extracting amodal information that takes the same form across modalities. From this perspective, speech integration is a property of the input information itself. Amodal speech information could explain the reported automaticity, immediacy, and completeness of audiovisual speech integration. However, recent findings suggest that speech integration can be influenced by higher cognitive properties such as lexical status and semantic context. Proponents of amodal accounts will need to explain these results.

Lip-read me now, hear me better later: cross-modal transfer of talker-familiarity effects.

There is evidence that for both auditory and visual speech perception, familiarity with the talker facilitates speech recognition. Explanations of these effects have concentrated on the retention of talker information specific to each of these modalities. It could be, however, that some amodal, talker-specific articulatory-style information facilitates speech perception in both modalities. If this is true, then experience with a talker in one modality should facilitate perception of speech from that talker in the other modality. In a test of this prediction, subjects were given about 1 hr of experience lipreading a talker and were then asked to recover speech in noise from either this same talker or a different talker. Results revealed that subjects who lip-read and heard speech from the same talker performed better on the speech-in-noise task than did subjects who lip-read from one talker and then heard speech from a different talker.

Look who's talking: recognizing friends from visible articulation.

We tested whether isolated visible articulatory information can be used for identifying familiar speakers. A facial point-light methodology was used to isolate the visible articulation of seven speakers. These point-light video clips were then shown to nine participants who had long-term personal interactions with the speakers. Results revealed that participants could identify the speakers at better than chance levels when the faces were shown articulating, but not when the faces were shown without movement. The results indicate that visible articulatory information can be used to identify speakers.

Hearing a face: cross-modal speaker matching using isolated visible speech.

An experiment was performed to test whether cross-modal speaker matches could be made using isolated visible speech movement information. Visible speech movements were isolated using a point-light technique. In five conditions, subjects were asked to match a voice to one of two (unimodal) speaking point-light faces on the basis of speaker identity. Two of these conditions were designed to maintain the idiosyncratic speech dynamics of the speakers, whereas three of the conditions deleted or distorted the dynamics in various ways. Some of these conditions also equated video frames across dynamically correct and distorted movements. The results revealed generally better matching performance in the conditions that maintained the correct speech dynamics than in those conditions that did not, despite containing exactly the same video frames. The results suggest that visible speech movements themselves can support cross-modal speaker matching.

Effects of intrastimulus modality change on audiovisual time-to-arrival judgments.

In this research, anticipatory perception of an approaching vehicle was examined. By varying the availability of visual and acoustic media, conditions occurred in which the input to the modalities was repetitively interrupted while the presentation of the approach event continued. In these conditions, the audio and the visual signals were presented either in short and concurrent segments at regular intervals or in alternation (interleaved) at regular intervals. It was found that interrupting the signal within a single modality did not affect performance if the approach information was available in the alternate modality. These results are consistent with a modally flexible detection mechanism for the perception of approaching objects. This modal flexibility may provide some evidence that information is detected using a modality-neutral strategy.

Visual speech information for face recognition.

Two experiments test whether isolated visible speech movements can be used for face matching. Visible speech information was isolated with a point-light methodology. Participants were asked to match articulating point-light faces to a fully illuminated articulating face in an XAB task. The first experiment tested single-frame static face stimuli as a control. The results revealed that the participants were significantly better at matching the dynamic face stimuli than the static ones. Experiment 2 tested whether the observed dynamic advantage was based on the movement itself or on the fact that the dynamic stimuli consisted of many more static and ordered frames. For this purpose, frame rate was reduced, and the frames were shown in a random order, a correct order with incorrect relative timing, or a correct order with correct relative timing. The results revealed better matching performance with the correctly ordered and timed frame stimuli, suggesting that matches were based on the actual movement itself. These findings suggest that speaker-specific visible articulatory style can provide information for face matching.