Auditory-vocal integration impairment: New challenges and opportunities for voice assessment and therapy

This reflection paper addresses the importance of the interaction between voice perception and voice production, emphasizing the processes of auditory-vocal integration that are not yet widely reported in the context of voice clinicians. Given the above, this article seeks to 1) highlight the important link between voice production and voice perception and 2) consider whether this relationship might be exploited clinically for diagnostic purposes and therapeutic benefit. Existing theories on speech production and its interaction with auditory perception provide context for discussing why the evaluation of auditory-vocal processes could help identify associated origins of dysphonia and inform the clinician around appropriate management strategies. Incorporating auditory-vocal integration assessment through sensorimotor adaptation paradigm testing could prove to be an important addition to voice assessment protocols at the clinical level. Further, if future studies can specify the means to manipulate and enhance a person’s auditory-vocal integration, the efficiency of voice therapy could be increased, leading to improved quality of life for people with voice disorders.

Categorical encoding of voice in human superior temporal cortex

The ability to recognize abstract features of voice during auditory perception is a complex, yet poorly understood, feat of human audition. For the listener, this occurs in near-automatic fasion to seamlessly extract complex cues from a highly variable auditory signal. Voice perception depends on specialized regions of auditory cortex, including superior temporal gyrus (STG) and superior temporal sulcus (STS). However, the nature of voice encoding at the cortical level remains poorly understoood. We leverage intracerebral recordings across human auditory cortex during presentation of voice and non-voice acoustic stimuli to examine voice encoding in auditory cortex, in eight patient-participants undergoing epilepsy surgery evaluation. We show that voice-selectivity increases along the auditory hierarchy from supratemporal plane (STP) to the STG and STS. Results show accurate decoding of vocalizations from human auditory cortical activity even in the complete absence of linguistic content. These findings show an early, less-selective temporal window of neural activity in the STG and STS followed by a sustained, strongly voice-selective window. We then developed encoding models that demonstrate divergence in the encoding of acoustic features along the auditory hierarchy, wherein STG/STS responses were best explained by voice category as opposed to the acoustic features of voice stimuli. This is in contrast to neural activity recorded from STP, in which responses were accounted for by acoustic features. These findings support a model of voice perception that engages categorical encoding mechanisms within STG and STS.

Unimodal and cross-modal identity judgements using an audio-visual sorting task: Evidence for independent processing of faces and voices

Unimodal and cross-modal information provided by faces and voices contribute to identity percepts. To examine how these sources of information interact, we devised a novel audio-visual sorting task in which participants were required to group video-only and audio-only clips into two identities. In a series of three experiments, we show that unimodal face and voice sorting were more accurate than cross-modal sorting: While face sorting was consistently most accurate followed by voice sorting, cross-modal sorting was at chancel level or below. In Experiment 1, we compared performance in our novel audio-visual sorting task to a traditional identity matching task, showing that unimodal and cross-modal identity perception were overall moderately more accurate than the traditional identity matching task. In Experiment 2, separating unimodal from cross-modal sorting led to small improvements in accuracy for unimodal sorting, but no change in cross-modal sorting performance. In Experiment 3, we explored the effect of minimal audio-visual training: Participants were shown a clip of the two identities in conversation prior to completing the sorting task. This led to small, nonsignificant improvements in accuracy for unimodal and cross-modal sorting. Our results indicate that unfamiliar face and voice perception operate relatively independently with no evidence of mutual benefit, suggesting that extracting reliable cross-modal identity information is challenging.

Vocal Fold Injection Augmentation for Post-Airway Reconstruction Dysphonia: A Case Series

Objectives: Post airway reconstruction dysphonia (PARD) is common and has a significant effect on the quality of life of patients. Vocal fold injection augmentation (VFIA) is one treatment that can be used to improve glottic insufficiency in some patients. The goal of this study was to characterize the use and outcomes of VFIA for PARD. Methods: Retrospective chart review from January 2007 to July 2018 at a tertiary pediatric care center. Consecutive patients with PARD who underwent VFIA, who had a preoperative voice evaluation and a follow-up evaluation within 3 months after VFIA (fat, carboxymethylcellulose gel, hyaluronic acid). Results: Thirty-four patients (20 female) underwent VFIA. The mean age at the time of the injection was 13.6 years (SD 6.1). Twenty patients (58.8%) had a history of prematurity and a mean of 1.8 open airway surgeries. After injection, 29/34 patients (85.3%) noted a subjective voice improvement. The baseline Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V) overall severity score decreased by a mean of 5.7 (SD = 19.6) points, P = .12. Total pediatric Voice Handicap Index (pVHI) improved by 6.0 (SD = 19.5) points, from 57.4 (SD = 20.0) to 51.4 (SD = 17.2), P = .09. Functional pVHI subscore demonstrated a significant improvement, with a decrease of 3.4 (SD = 7.3) points, P = .02. All procedures were performed as an overnight observation and no complication occurred. Conclusion: Patients with PARD represent a complex subset of patients. VFIA is a straightforward intervention that may improve voice perception. Many patients reported subjective improvement despite minimal objective measurement. Further work is warranted to elucidate the role of injection in management of PARD

Recognizing voices through a cochlear implant: A systematic review

Objective: Some cochlear implant (CI) users report having difficulty accessing indexical information in the speech signal, presumably due to the transformation from acoustic to electric signal in CI devices. The purpose of this paper was to systematically review and evaluate the existing research on talker perception in CI users. Specifically, we reviewed the performance of CI users in talker discrimination, gender identification, and talker recognition tasks in relation to performance by normal-hearing (NH) listeners. We also examined the different factors (such asparticipant, hearing and device characteristics) that might influence talker perception.Design: We completed a systematic search of the literature with select keywords using citation aggregation software to search Google Scholar. We included primary reports that had at least one group of participants with cochlear implants, and had an experimental task that measured talker or voice perception. Each included study was also evaluated for quality of evidence.Results: The initial search resulted in 1239 references, which were first screened for inclusion and then evaluated in full. Thirty-nine studies examining talker identification, talker discrimimnation, and gender discrimination were included in the final review. The majority of studies were focused on adult postlingual cochlear implant users, with a few studies focused on prelingual implant users. As a group, CI users generally performed above chance in talker perception tasks, but performed worse than NH controls. Nonetheless, a subset of CI users reached the same level of performance as NH participants. CI users relied more heavily on fundamental frequency over vocal tract length cues to distinguish talkers compared to NH listeners. Within groups of CI users, there is moderate evidence for a bimodal benefit for talker perception, and there are mixed findings about the effects of hearing experience. Performance in talker discrimination tasks was related to other linguistic tasks, including word recognition. Conclusion: The current review highlights the challenges faced by CI users in tracking and recognizing voices and how they adapt to it. There is clear evidence that CI users can process indexical information, albeit differently and more effortfully than NH listeners. Recent work has begun to describe some of the factors that might ease the challenges of talker perception in CI users, but further high-quality research is needed to disentangle some of the mixed findings. We conclude by suggesting some future avenues of research to optimize real-world speech outcomes.

Talker and accent familiarity yield advantages for voice identity perception: a voice sorting study

Familiarity benefits in voice identity perception have been frequently described in the literature. Typically, studies have contrasted listeners who were either familiar or unfamiliar with the target voices, thus manipulating talker familiarity. In these studies, familiarity with a voice results in more accurate voice identity perception. Such talker familiarity is, however, only one way in which listeners can be familiar the stimuli used: Another type of familiarity that has been shown to benefit voice identity perception is language or accent familiarity. In the current study, we examine and compare the effects of talker and accent familiarity in the context of a voice identity sorting task, using naturally varying voice recording samples from the TV show “Derry Girls”. Voice samples were thus all spoken with a regional accent of UK/Irish English (Northern Irish). We tested four listeners groups: Listeners were either familiar or unfamiliar with the TV show (and therefore the talker identities) and were either highly familiar or relatively less familiar with the accent. We find that both talker and accent familiarity significantly improve accuracy of voice identity perception. However, the effect sizes for effects of talker familiarity are overall larger. We discuss our findings in light of existing models of voice perception, arguing that they provide evidence for interactions of speech and identity processing pathways in voice perception. We conclude that voice perception is a highly interactive process, during which listeners make use of any available information to achieve their perceptual goals.