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.     

Effects of culture on musical pitch perception

The strong association between music and speech has been supported by recent research focusing on musicians' superior abilities in second language learning and neural encoding of foreign speech sounds. However, evidence for a double association--the influence of linguistic background on music pitch processing and disorders--remains elusive. Because languages differ in their usage of elements (e.g., pitch) that are also essential for music, a unique opportunity for examining such language-to-music associations comes from a cross-cultural (linguistic) comparison of congenital amusia, a neurogenetic disorder affecting the music (pitch and rhythm) processing of about 5% of the Western population. In the present study, two populations (Hong Kong and Canada) were compared. One spoke a tone language in which differences in voice pitch correspond to differences in word meaning (in Hong Kong Cantonese, /si/ means 'teacher' and 'to try' when spoken in a high and mid pitch pattern, respectively). Using the On-line Identification Test of Congenital Amusia, we found Cantonese speakers as a group tend to show enhanced pitch perception ability compared to speakers of Canadian French and English (non-tone languages). This enhanced ability occurs in the absence of differences in rhythmic perception and persists even after relevant factors such as musical background and age were controlled. Following a common definition of amusia (5% of the population), we found Hong Kong pitch amusics also show enhanced pitch abilities relative to their Canadian counterparts. These findings not only provide critical evidence for a double association of music and speech, but also argue for the reconceptualization of communicative disorders within a cultural framework. Along with recent studies documenting cultural differences in visual perception, our auditory evidence challenges the common assumption of universality of basic mental processes and speaks to the domain generality of culture-to-perception influences.     

Co-variation of tonality in the music and speech of different cultures

Whereas the use of discrete pitch intervals is characteristic of most musical traditions, the size of the intervals and the way in which they are used is culturally specific. Here we examine the hypothesis that these differences arise because of a link between the tonal characteristics of a culture's music and its speech. We tested this idea by comparing pitch intervals in the traditional music of three tone language cultures (Chinese, Thai and Vietnamese) and three non-tone language cultures (American, French and German) with pitch intervals between voiced speech segments. Changes in pitch direction occur more frequently and pitch intervals are larger in the music of tone compared to non-tone language cultures. More frequent changes in pitch direction and larger pitch intervals are also apparent in the speech of tone compared to non-tone language cultures. These observations suggest that the different tonal preferences apparent in music across cultures are closely related to the differences in the tonal characteristics of voiced speech.     

Congenital amusia persists in the developing brain after daily music listening

Congenital amusia is a neurodevelopmental disorder that affects about 3% of the adult population. Adults experiencing this musical disorder in the absence of macroscopically visible brain injury are described as cases of congenital amusia under the assumption that the musical deficits have been present from birth. Here, we show that this disorder can be expressed in the developing brain. We found that (10-13 year-old) children exhibit a marked deficit in the detection of fine-grained pitch differences in both musical and acoustical context in comparison to their normally developing peers comparable in age and general intelligence. This behavioral deficit could be traced down to their abnormal P300 brain responses to the detection of subtle pitch changes. The altered pattern of electrical activity does not seem to arise from an anomalous functioning of the auditory cortex, because all early components of the brain potentials, the N100, the MMN, and the P200 appear normal. Rather, the brain and behavioral measures point to disrupted information propagation from the auditory cortex to other cortical regions. Furthermore, the behavioral and neural manifestations of the disorder remained unchanged after 4 weeks of daily musical listening. These results show that congenital amusia can be detected in childhood despite regular musical exposure and normal intellectual functioning.     

Effects of Early Bilingual Experience with a Tone and a Non-Tone Language on Speech-Music Integration

We investigated music and language processing in a group of early bilinguals who spoke a tone language and a non-tone language (Cantonese and Dutch). We assessed online speech-music processing interactions, that is, interactions that occur when speech and music are processed simultaneously in songs, with a speeded classification task. In this task, participants judged sung pseudowords either musically (based on the direction of the musical interval) or phonologically (based on the identity of the sung vowel). We also assessed longer-term effects of linguistic experience on musical ability, that is, the influence of extensive prior experience with language when processing music. These effects were assessed with a task in which participants had to learn to identify musical intervals and with four pitch-perception tasks. Our hypothesis was that due to their experience in two different languages using lexical versus intonational tone, the early Cantonese-Dutch bilinguals would outperform the Dutch control participants. In online processing, the Cantonese-Dutch bilinguals processed speech and music more holistically than controls. This effect seems to be driven by experience with a tone language, in which integration of segmental and pitch information is fundamental. Regarding longer-term effects of linguistic experience, we found no evidence for a bilingual advantage in either the music-interval learning task or the pitch-perception tasks. Together, these results suggest that being a Cantonese-Dutch bilingual does not have any measurable longer-term effects on pitch and music processing, but does have consequences for how speech and music are processed jointly.     

Individual Differences in the Discrimination of Novel Speech Sounds: Effects of Sex,Temporal Processing,Musical and Cognitive Abilities

This study examined whether rapid temporal auditory processing, verbal working memory capacity, non-verbal intelligence, executive functioning, musical ability and prior foreign language experience predicted how well native English speakers (N = 120) discriminated Norwegian tonal and vowel contrasts as well as a non-speech analogue of the tonal contrast and a native vowel contrast presented over noise. Results confirmed a male advantage for temporal and tonal processing, and also revealed that temporal processing was associated with both non-verbal intelligence and speech processing. In contrast, effects of musical ability on non-native speech-sound processing and of inhibitory control on vowel discrimination were not mediated by temporal processing. These results suggest that individual differences in non-native speech-sound processing are to some extent determined by temporal auditory processing ability, in which males perform better, but are also determined by a host of other abilities that are deployed flexibly depending on the characteristics of the target sounds.     

先天性音乐障碍者音乐加工障碍及其特异性争议

人群中存在少量先天性音乐障碍(congenital amusia)个体,表现出音乐感知和表达方面有选择性障碍。本文总结了前人甄别先天性音乐障碍个体的工具,述评了先天性音乐障碍者对音乐加工时的障碍表现,以及先天性音乐障碍者其障碍领域特异性争议,并从行为遗传学和音乐加工脑机制角度,综述了先天性音乐障碍者可能的原因,最后对先天性音乐障碍未来可能的研究方向做了四个方面的展望。     

Music perception: sounds lost in space

A recent study of spatial processing in amusia makes a controversial claim that such musical deficits may be understood in terms of a problem in the representation of space. If such a link is demonstrated to be causal, it would challenge the prevailing view that deficits in amusia are specific to the musical or even the auditory domain.     

The genetics of congenital amusia (tone deafness): a family-aggregation study

Congenital amusia (commonly known as “tone deafness”) is a lifelong impairment of music perception that affects 4% of the population. To estimate whether congenital amusia can be genetically transmitted, its prevalence was quantified by direct auditory testing of 71 members of 9 large families of amusic probands, as well as of 75 members of 10 control families. The results confirm that congenital amusia is expressed by a deficit in processing musical pitch but not musical time and also show that the pitch disorder has a hereditary component. In amusic families, 39% of first-degree relatives have the same cognitive disorder, whereas only 3% have it in the control families. The identification of multiplex families with a high relative risk of experiencing a musical pitch deficit (λ_s=10.8; 95% confidence interval 8–13.5) enables the mapping of genetic loci for hereditary amusia.     

Congenital amusia: a disorder of fine-grained pitch discrimination.

We report the first documented case of congenital amusia. This disorder refers to a musical disability that cannot be explained by prior brain lesion, hearing loss, cognitive deficits, socioaffective disturbance, or lack of environmental stimulation. This musical impairment is diagnosed in a middle-aged woman, hereafter referred to as Monica, who lacks most basic musical abilities, including melodic discrimination and recognition, despite normal audiometry and above-average intellectual, memory, and language skills. The results of psychophysical tests show that Monica has severe difficulties with detecting pitch changes. The data suggest that music-processing difficulties may result from problems in fine-grained discrimination of pitch, much in the same way as many language-processing difficulties arise from deficiencies in auditory temporal resolution.     

Expression of emotion in Eastern and Western music mirrors vocalization

In Western music, the major mode is typically used to convey excited, happy, bright or martial emotions, whereas the minor mode typically conveys subdued, sad or dark emotions. Recent studies indicate that the differences between these modes parallel differences between the prosodic and spectral characteristics of voiced speech sounds uttered in corresponding emotional states. Here we ask whether tonality and emotion are similarly linked in an Eastern musical tradition. The results show that the tonal relationships used to express positive/excited and negative/subdued emotions in classical South Indian music are much the same as those used in Western music. Moreover, tonal variations in the prosody of English and Tamil speech uttered in different emotional states are parallel to the tonal trends in music. These results are consistent with the hypothesis that the association between musical tonality and emotion is based on universal vocal characteristics of different affective states.     

Real-Time Correlates of Phonological Quantity Reveal Unity of Tonal and Non-Tonal Languages

Discrete phonological phenomena form our conscious experience of language: continuous changes in pitch appear as distinct tones to the speakers of tone languages, whereas the speakers of quantity languages experience duration categorically. The categorical nature of our linguistic experience is directly reflected in the traditionally clear-cut linguistic classification of languages into tonal or non-tonal. However, some evidence suggests that duration and pitch are fundamentally interconnected and co-vary in signaling word meaning in non-tonal languages as well. We show that pitch information affects real-time language processing in a (non-tonal) quantity language. The results suggest that there is no unidirectional causal link from a genetically-based perceptual sensitivity towards pitch information to the appearance of a tone language. They further suggest that the contrastive categories tone and quantity may be based on simultaneously co-varying properties of the speech signal and the processing system, even though the conscious experience of the speakers may highlight only one discrete variable at a time.     

Learning Pitch with STDP: A Computational Model of Place and Temporal Pitch Perception Using Spiking Neural Networks

Pitch perception is important for understanding speech prosody, music perception, recognizing tones in tonal languages, and perceiving speech in noisy environments. The two principal pitch perception theories consider the place of maximum neural excitation along the auditory nerve and the temporal pattern of the auditory neurons’ action potentials (spikes) as pitch cues. This paper describes a biophysical mechanism by which fine-structure temporal information can be extracted from the spikes generated at the auditory periphery. Deriving meaningful pitch-related information from spike times requires neural structures specialized in capturing synchronous or correlated activity from amongst neural events. The emergence of such pitch-processing neural mechanisms is described through a computational model of auditory processing. Simulation results show that a correlation-based, unsupervised, spike-based form of Hebbian learning can explain the development of neural structures required for recognizing the pitch of simple and complex tones, with or without the fundamental frequency. The temporal code is robust to variations in the spectral shape of the signal and thus can explain the phenomenon of pitch constancy.     

音乐绝对音高行为研究述评

音乐绝对音高(musical absolute pitch,AP)能力是一种敏锐的乐音音高知觉分类和记忆能力,表现为在没有任何其它音高参照的情况下,能够对所听到乐音音高进行准确命名或分类。本文从音乐绝对音高甄别方法、基因遗传、早期音乐训练、语言环境对音乐绝对音高能力形成的影响,以及绝对音高与音乐能力、音乐记忆和空间能力方面的研究进行了介绍,提出研究音乐绝对音高的重要性。最后展望了音乐绝对音高领域未来可能的四个研究方向。     

Improving language and literacy is a matter of time

Developmental deficits that affect speech perception increase the risk of language and literacy problems, which can lead to lowered academic and occupational accomplishment. Normal development and disorders of speech perception have both been linked to temporospectral auditory processing speed. Understanding the role of dynamic auditory processing in speech perception and language comprehension has led to the development of neuroplasticity-based intervention strategies aimed at ameliorating language and literacy problems and their sequelae.     

The Pitch Imagery Arrow Task: Effects of Musical Training,Vividness, and Mental Control

Musical imagery is a relatively unexplored area, partly because of deficiencies in existing experimental paradigms, which are often difficult, unreliable, or do not provide objective measures of performance. Here we describe a novel protocol, the Pitch Imagery Arrow Task (PIAT), which induces and trains pitch imagery in both musicians and non-musicians. Given a tonal context and an initial pitch sequence, arrows are displayed to elicit a scale-step sequence of imagined pitches, and participants indicate whether the final imagined tone matches an audible probe. It is a staircase design that accommodates individual differences in musical experience and imagery ability. This new protocol was used to investigate the roles that musical expertise, self-reported auditory vividness and mental control play in imagery performance. Performance on the task was significantly better for participants who employed a musical imagery strategy compared to participants who used an alternative cognitive strategy and positively correlated with scores on the Control subscale from the Bucknell Auditory Imagery Scale (BAIS). Multiple regression analysis revealed that Imagery performance accuracy was best predicted by a combination of strategy use and scores on the Vividness subscale of BAIS. These results confirm that competent performance on the PIAT requires active musical imagery and is very difficult to achieve using alternative cognitive strategies. Auditory vividness and mental control were more important than musical experience in the ability to perform manipulation of pitch imagery.     

Hearing feelings: affective categorization of music and speech in alexithymia, an ERP study

Background

Alexithymia, a condition characterized by deficits in interpreting and regulating feelings, is a risk factor for a variety of psychiatric conditions. Little is known about how alexithymia influences the processing of emotions in music and speech. Appreciation of such emotional qualities in auditory material is fundamental to human experience and has profound consequences for functioning in daily life. We investigated the neural signature of such emotional processing in alexithymia by means of event-related potentials.

Methodology

Affective music and speech prosody were presented as targets following affectively congruent or incongruent visual word primes in two conditions. In two further conditions, affective music and speech prosody served as primes and visually presented words with affective connotations were presented as targets. Thirty-two participants (16 male) judged the affective valence of the targets. We tested the influence of alexithymia on cross-modal affective priming and on N400 amplitudes, indicative of individual sensitivity to an affective mismatch between words, prosody, and music. Our results indicate that the affective priming effect for prosody targets tended to be reduced with increasing scores on alexithymia, while no behavioral differences were observed for music and word targets. At the electrophysiological level, alexithymia was associated with significantly smaller N400 amplitudes in response to affectively incongruent music and speech targets, but not to incongruent word targets.

Conclusions

Our results suggest a reduced sensitivity for the emotional qualities of speech and music in alexithymia during affective categorization. This deficit becomes evident primarily in situations in which a verbalization of emotional information is required.     

Influence of Musical Training on Understanding Voiced and Whispered Speech in Noise

This study tested the hypothesis that the previously reported advantage of musicians over non-musicians in understanding speech in noise arises from more efficient or robust coding of periodic voiced speech, particularly in fluctuating backgrounds. Speech intelligibility was measured in listeners with extensive musical training, and in those with very little musical training or experience, using normal (voiced) or whispered (unvoiced) grammatically correct nonsense sentences in noise that was spectrally shaped to match the long-term spectrum of the speech, and was either continuous or gated with a 16-Hz square wave. Performance was also measured in clinical speech-in-noise tests and in pitch discrimination. Musicians exhibited enhanced pitch discrimination, as expected. However, no systematic or statistically significant advantage for musicians over non-musicians was found in understanding either voiced or whispered sentences in either continuous or gated noise. Musicians also showed no statistically significant advantage in the clinical speech-in-noise tests. Overall, the results provide no evidence for a significant difference between young adult musicians and non-musicians in their ability to understand speech in noise.     

Congenital amusia: all the songs sound the same

Recent evidence from individuals born with a profound musical impairment suggests that the ability to process pitch information is normally present from birth. This finding supports the idea that the perception and appreciation of music, both of which critically depend on pitch processing, have a biological basis in the brain.     

Hearing and seeing meaning in speech and gesture: insights from brain and behaviour

As we speak, we use not only the arbitrary form–meaning mappings of the speech channel but also motivated form–meaning correspondences, i.e. iconic gestures that accompany speech (e.g. inverted V-shaped hand wiggling across gesture space to demonstrate walking). This article reviews what we know about processing of semantic information from speech and iconic gestures in spoken languages during comprehension of such composite utterances. Several studies have shown that comprehension of iconic gestures involves brain activations known to be involved in semantic processing of speech: i.e. modulation of the electrophysiological recording component N400, which is sensitive to the ease of semantic integration of a word to previous context, and recruitment of the left-lateralized frontal–posterior temporal network (left inferior frontal gyrus (IFG), medial temporal gyrus (MTG) and superior temporal gyrus/sulcus (STG/S)). Furthermore, we integrate the information coming from both channels recruiting brain areas such as left IFG, posterior superior temporal sulcus (STS)/MTG and even motor cortex. Finally, this integration is flexible: the temporal synchrony between the iconic gesture and the speech segment, as well as the perceived communicative intent of the speaker, modulate the integration process. Whether these findings are special to gestures or are shared with actions or other visual accompaniments to speech (e.g. lips) or other visual symbols such as pictures are discussed, as well as the implications for a multimodal view of language.