Congenital amusia is a neurodevelopmental disorder of musical processing that also impacts subtle aspects of speech processing. It remains debated at what stage(s) of auditory processing deficits in amusia arise. In this study, we investigated whether amusia originates from impaired subcortical encoding of speech (in quiet and noise) and musical sounds in the brainstem. Fourteen Cantonese-speaking amusics and 14 matched controls passively listened to six Cantonese lexical tones in quiet, two Cantonese tones in noise (signal-to-noise ratios at 0 and 20 dB), and two cello tones in quiet while their frequency-following responses (FFRs) to these tones were recorded. All participants also completed a behavioral lexical tone identification task. The results indicated normal brainstem encoding of pitch in speech (in quiet and noise) and musical stimuli in amusics relative to controls, as measured by FFR pitch strength, pitch error, and stimulus-to-response correlation. There was also no group difference in neural conduction time or FFR amplitudes. Both groups demonstrated better FFRs to speech (in quiet and noise) than to musical stimuli. However, a significant group difference was observed for tone identification, with amusics showing significantly lower accuracy than controls. Analysis of the tone confusion matrices suggested that amusics were more likely than controls to confuse between tones that shared similar acoustic features. Interestingly, this deficit in lexical tone identification was not coupled with brainstem abnormality for either speech or musical stimuli. Together, our results suggest that the amusic brainstem is not functioning abnormally, although higher-order linguistic pitch processing is impaired in amusia. This finding has significant implications for theories of central auditory processing, requiring further investigations into how different stages of auditory processing interact in the human brain.

Musical experience and linguistic experience have been shown to facilitate language and music perception. However, the precise nature of music and language interaction is still a subject of ongoing research. In this study, using subcortical electrophysiological measures (frequency following response), we seek to understand the effect of interaction of linguistic pitch experience and musical pitch experience on subcortical lexical and musical pitch encoding. We compared musicians and non-musicians who were native speakers of a tone language on subcortical encoding of linguistic and musical pitch. We found that musicians and non-musicians did not differ on the brainstem encoding of lexical tones. However, musicians showed a more robust brainstem encoding of musical pitch as compared to non-musicians. These findings suggest that a combined musical and linguistic pitch experience affects auditory brainstem encoding of linguistic and musical pitch differentially. From our results, we could also speculate that native tone language speakers might use two different mechanisms, at least for the subcortical encoding of linguistic and musical pitch.

The current study revealed that the four subsections of STAP merged to form three distinct components. Dichotic CV and gap detection formed two independent components while speech perception in noise and auditory memory merged to form a single component. This indicates a possible relationship between auditory memory and speech perception in noise as suggested by Katz (1992). Thus, STAP is able to detect three different components related to auditory processing. The study also indicates that the number of children at risk for each of the different auditory processes vary. Ongoing evaluation will shed light on the usefulness of the subsections of STAP in identifying auditory processing problems. In addition to conducting the APD screening test, it is also recommended that a hearing screening be done to rule out peripheral hearing problems when hearing screening programs are not conducted in schools.

We investigated the development of early-latency and long-latency brain responses to native and non-native speech to shed light on the neurophysiological underpinnings of perceptual narrowing and early language development. Specifically, we postulated a two-level process to explain the decrease in sensitivity to non-native phonemes towards the end of infancy. Neurons at the earlier stages of the ascending auditory pathway mature rapidly during infancy facilitating the encoding of both native and non-native sounds. This growth enables neurons at the later stages of the auditory pathway to assign phonological status to speech according to the infant’s native language environment. To test this hypothesis, we collected early- latency and long-latency neural responses to native and non-native lexical tones from 85 Cantoneselearning children aged between 23 days and 24 months and 16 days. As expected, a broad range of presumably subcortical early-latency neural encoding measures grew rapidly and substantially during the first two years for both native and non-native tones. By contrast, longlatency cortical electrophysiological changes occurred on a much slower scale and showed sensitivity to nativeness at around six months. Our study provided a comprehensive understanding of early language development by revealing the complementary roles of earlier and later stages of speech processing in the developing brain.

Purpose This study aimed to construct an objective and cost-effective prognostic tool to forecast the future language and communication abilities of individual infants. Method Speech-evoked electroencephalography (EEG) data were collected from 118 infants during the first year of life during the exposure to speech stimuli that differed principally in fundamental frequency. Language and communication outcomes, namely four subtests of the MacArthur–Bates Communicative Development Inventories (MCDI)–Chinese version, were collected between 3 and 16 months after initial EEG testing. In the two-way classification, children were classified into those with future MCDI scores below the 25th percentile for their age group and those above the same percentile, while the three-way classification classified them into < 25th, 25th–75th, and > 75th percentile groups. Machine learning (support vector machine classification) with cross validation was used for model construction. Statistical significance was assessed. Results Across the four MCDI measures of early gestures, later gestures, vocabulary comprehension, and vocabulary production, the areas under the receiver-operating characteristic curve of the predictive models were respectively .92 ± .031, .91 ± .028, .90 ± .035, and .89 ± .039 for the two-way classification, and .88 ± .041, .89 ± .033, .85 ± .047, and .85 ± .050 for the three-way classification ( p < .01 for all models). Conclusions Future language and communication variability can be predicted by an objective EEG method that indicates the function of the auditory neural pathway foundational to spoken language development, with precision sufficient for individual predictions. Longer-term research is needed to assess predictability of categorical diagnostic status. Supplemental Material https://doi.org/10.23641/asha.15138546

Research studies provide evidence for the facilitative effects of musical and linguistic experience on lexical pitch learning. However, the effect of interaction of linguistic and musical pitch experience on lexical pitch processing is a matter of ongoing research. In the current study, we sought to examine the effect of combination of musical and linguistic pitch experience on learning of novel lexical pitch. Using a 10session pseudoword-picture association training paradigm, we compared the learning performance of musicians and nonmusicians who either spoke a non-tone language, spoke one tone language, or spoke two tone languages. Among the nontone language speakers, we found that musicians showed enhanced learning of novel lexical pitch as compared to nonmusicians. In comparison, among the tone-language speakers, we found no significant difference in the learning performance of musicians and non-musicians no matter they spoke one or more tone languages. We conclude that though musical experience facilitates linguistic pitch learning, the effects of combination of musical and linguistic pitch experience are not additive i.e. possessing both types of pitch experience is no better than possessing either one of them and knowing two tone languages does not facilitate the learning of a new tone language beyond the knowledge of one.

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Across time, languages undergo changes in phonetic, syntactic, and semantic dimensions. Social, cognitive, and cultural factors contribute to sound change, a phenomenon in which the phonetics of a language undergo changes over time. Individuals who misperceive and produce speech in a slightly divergent manner (called innovators) contribute to variability in the society, eventually leading to sound change. However, the cause of variability in these individuals is still unknown. In this study, we examined whether such misperceptions are represented in neural processes of the auditory system. We investigated behavioral, subcortical (via FFR), and cortical (via P300) manifestations of sound change processing in Cantonese, a Chinese language in which several lexical tones are merging. Across the merging categories, we observed a similar gradation of speech perception abilities in both behavior and the brain (subcortical and cortical processes). Further, we also found that behavioral evidence of tone merging correlated with subjects' encoding at the subcortical and cortical levels. These findings indicate that tone-merger categories, that are indicators of sound change in Cantonese, are represented neurophysiologically with high fidelity. Using our results, we speculate that innovators encode speech in a slightly deviant neurophysiological manner, and thus produce speech divergently that eventually spreads across the community and contributes to sound change.