Cunmei Jiang

The mechanism of speech processing in congenital amusia: Evidence from Mandarin speakers

Congenital amusia is a neuro-developmental disorder of pitch perception that causes severe problems with music processing but only subtle difficulties in speech processing. This study investigated speech processing in a group of Mandarin speakers with congenital amusia. Thirteen Mandarin amusics and thirteen matched controls participated in a set of tone and intonation perception tasks and two pitch threshold tasks. Compared with controls, amusics showed impaired performance on word discrimination in natural speech and their gliding tone analogs. They also performed worse than controls on discriminating gliding tone sequences derived from statements and questions, and showed elevated thresholds for pitch change detection and pitch direction discrimination. However, they performed as well as controls on word identification, and on statement-question identification and discrimination in natural speech. Overall, tasks that involved multiple acoustic cues to communicative meaning were not impacted by amusia. Only when the tasks relied mainly on pitch sensitivity did amusics show impaired performance compared to controls. These findings help explain why amusia only affects speech processing in subtle ways. Further studies on a larger sample of Mandarin amusics and on amusics of other language backgrounds are needed to consolidate these results.

Amusia Results in Abnormal Brain Activity following Inappropriate Intonation during Speech Comprehension

Pitch processing is a critical ability on which humans’ tonal musical experience depends, and which is also of paramount importance for decoding prosody in speech. Congenital amusia refers to deficits in the ability to properly process musical pitch, and recent evidence has suggested that this musical pitch disorder may impact upon the processing of speech sounds. Here we present the first electrophysiological evidence demonstrating that individuals with amusia who speak Mandarin Chinese are impaired in classifying prosody as appropriate or inappropriate during a speech comprehension task. When presented with inappropriate prosody stimuli, control participants elicited a larger P600 and smaller N100 relative to the appropriate condition. In contrast, amusics did not show significant differences between the appropriate and inappropriate conditions in either the N100 or the P600 component. This provides further evidence that the pitch perception deficits associated with amusia may also affect intonation processing during speech comprehension in those who speak a tonal language such as Mandarin, and suggests music and language share some cognitive and neural resources.

A music perception disorder (congenital amusia) influences speech comprehension.

This study investigated the underlying link between speech and music by examining whether and to what extent congenital amusia, a musical disorder characterized by degraded pitch processing, would impact spoken sentence comprehension for speakers of Mandarin, a tone language. Sixteen Mandarin-speaking amusics and 16 matched controls were tested on the intelligibility of news-like Mandarin sentences with natural and flat fundamental frequency (F0) contours (created via speech resynthesis) under four signal-to-noise (SNR) conditions (no noise, +5, 0, and -5dB SNR). While speech intelligibility in quiet and extremely noisy conditions (SNR=-5dB) was not significantly compromised by flattened F0, both amusic and control groups achieved better performance with natural-F0 sentences than flat-F0 sentences under moderately noisy conditions (SNR=+5 and 0dB). Relative to normal listeners, amusics demonstrated reduced speech intelligibility in both quiet and noise, regardless of whether the F0 contours of the sentences were natural or flattened. This deficit in speech intelligibility was not associated with impaired pitch perception in amusia. These findings provide evidence for impaired speech comprehension in congenital amusia, suggesting that the deficit of amusics extends beyond pitch processing and includes segmental processing.

Difficulties with Pitch Discrimination Influences Pitch Memory Performance: Evidence from Congenital Amusia

Music processing is influenced by pitch perception and memory. Additionally these features interact, with pitch memory performance decreasing as the perceived distance between two pitches decreases. This study examined whether or not the difficulty of pitch discrimination influences pitch retention by testing individuals with congenital amusia. Pitch discrimination difficulty was equated by determining an individual’s threshold with a two down one up staircase procedure and using this to create conditions where two pitches (the standard and the comparison tones) differed by 1x, 2x, and 3x the threshold setting. For comparison with the literature a condition that employed a constant pitch difference of four semitones was also included. The results showed that pitch memory performance improved as the discrimination between the standard and the comparison tones was made easier for both amusic and control groups, and more importantly, that amusics did not show any pitch retention deficits when the discrimination difficulty was equated. In contrast, consistent with previous literature, amusics performed worse than controls when the physical pitch distance was held constant at four semitones. This impaired performance has been interpreted as evidence for pitch memory impairment in the past. However, employing a constant pitch distance always makes the difference closer to the discrimination threshold for the amusic group than for the control group. Therefore, reduced performance in this condition may simply reflect differences in the perceptual difficulty of the discrimination. The findings indicate the importance of equating the discrimination difficulty when investigating memory.

Individuals with congenital amusia imitate pitches more accurately in singing than in speaking: implications for music and language processing

In this study, we investigated the impact of congenital amusia, a disorder of musical processing, on speech and song imitation in speakers of a tone language, Mandarin. A group of 13 Mandarin-speaking individuals with congenital amusia and 13 matched controls were recorded while imitating a set of speech and two sets of song stimuli with varying pitch and rhythm patterns. The results indicated that individuals with congenital amusia were worse than controls in both speech and song imitation, in terms of both pitch matching (absolute and relative) and rhythm matching (relative time and number of time errors). Like the controls, individuals with congenital amusia achieved better absolute and relative pitch matching and made fewer pitch interval and contour errors in song than in speech imitation. These findings point toward domain-general pitch (and time) production deficits in congenital amusia, suggesting the presence of shared pitch production mechanisms but distinct requirements for pitch-matching accuracy in language and music processing.

Perception of Melodic Contour and Intonation in Autism Spectrum Disorder: Evidence From Mandarin Speakers

Tone language experience benefits pitch processing in music and speech for typically developing individuals. No known studies have examined pitch processing in individuals with autism who speak a tone language. This study investigated discrimination and identification of melodic contour and speech intonation in a group of Mandarin-speaking individuals with high-functioning autism. Individuals with autism showed superior melodic contour identification but comparable contour discrimination relative to controls. In contrast, these individuals performed worse than controls on both discrimination and identification of speech intonation. These findings provide the first evidence for differential pitch processing in music and speech in tone language speakers with autism, suggesting that tone language experience may not compensate for speech intonation perception deficits in individuals with autism.

Impaired Explicit Processing of Musical Syntax and Tonality in a Group of Mandarin-Speaking Congenital Amusics

We examined explicit processing of musical syntax and tonality in a group of Han Chinese Mandarin speakers with congenital amusia, and the extent to which pitch discrimination impairments were associated with syntax and tonality processing. In Experiment 1, we assessed whether congenital amusia is associated with impaired explicit processing of musical syntax. Congruity ratings were examined for syntactically regular or irregular endings in harmonic and melodic contexts. Unlike controls, amusic participants failed to explicitly distinguish regular from irregular endings in both contexts. Surprisingly, however, a concurrent manipulation of pitch distance did not affect the processing of musical syntax for amusics, and their impaired music-syntactic processing was uncorrelated with their pitch discrimination thresholds. In Experiment 2, we assessed tonality perception using a probe-tone paradigm. Recovery of the tonal hierarchy was less evident for the amusic group than for the control group, and this reduced sensitivity to tonality in amusia was also unrelated to poor pitch discrimination. These findings support the view that music structure is processed by cognitive and neural resources that operate independently of pitch discrimination, and that these resources are impaired in explicit judgments for individuals with congenital amusia.

Conveying the concept of movement in music: An event-related brain potential study.

This study on event-related brain potential investigated whether music can convey the concept of movement. Using a semantic priming paradigm, natural musical excerpts were presented to non-musicians, followed by semantically congruent or incongruent pictures that depicted objects either in motion or at rest. The priming effects were tested in object decision and implicit recognition tasks to distinguish the effects of automatic conceptual activation from response competition. Results showed that in both tasks, pictures that were incongruent to preceding musical excerpts elicited larger N400 than congruent pictures, suggesting that music can prime the representations of movement concepts. Results of the multiple regression analysis showed that movement expression could be well predicted by specific acoustic and musical features, indicating the associations between music per se and the processing of iconic musical meaning.

Spatial conceptual associations between music and pictures as revealed by N400 effect

The processing of extramusical meaning can be reflected in N400 effects of the ERP. However, how conceptual representations can be activated in music still needs to be specified. We investigated the activation of iconic meaningful representations in music by using a cross-modal semantic priming paradigm with an implicit task. Pictures of spatial scenes were semantically congruent or incongruent to preceding music in three stimulus onset asynchrony (SOA) conditions. The results revealed that the semantically incongruent target pictures elicited larger N400 amplitude than the congruent target pictures. Moreover, the semantic priming effect was modulated by the SOAs. The N400 effect was observed in the 200-ms and 800-ms SOA conditions, but not in the 1,200-ms SOA condition. These results suggest that extramusical meaning purely due to iconic sign quality can be activated, and that the conceptual activation in music can be rapid and automatic.

Sensitivity to musical emotion is influenced by tonal structure in congenital amusia

Emotional communication in music depends on multiple attributes including psychoacoustic features and tonal system information, the latter of which is unique to music. The present study investigated whether congenital amusia, a lifelong disorder of musical processing, impacts sensitivity to musical emotion elicited by timbre and tonal system information. Twenty-six amusics and 26 matched controls made tension judgments on Western (familiar) and Indian (unfamiliar) melodies played on piano and sitar. Like controls, amusics used timbre cues to judge musical tension in Western and Indian melodies. While controls assigned significantly lower tension ratings to Western melodies compared to Indian melodies, thus showing a tonal familiarity effect on tension ratings, amusics provided comparable tension ratings for Western and Indian melodies on both timbres. Furthermore, amusics rated Western melodies as more tense compared to controls, as they relied less on tonality cues than controls in rating tension for Western melodies. The implications of these findings in terms of emotional responses to music are discussed.