Focal Brain Lesions Causing Acquired Amusia Map to a Common Brain Network.

Music is a universal human attribute. The study of amusia, a neurologic music processing deficit, has increasingly elaborated our view on the neural organization of the musical brain. However, lesions causing amusia occur in multiple brain locations and often also cause aphasia, leaving the distinct neural networks for amusia unclear. Here, we utilized lesion network mapping to identify these networks. A systematic literature search was carried out to identify all published case reports of lesion-induced amusia. The reproducibility and specificity of the identified amusia network were then tested in an independent prospective cohort of 97 stroke patients (46 female and 51 male) with repeated structural brain imaging, specifically assessed for both music perception and language abilities. Lesion locations in the case reports were heterogeneous but connected to common brain regions, including bilateral temporoparietal and insular cortices, precentral gyrus, and cingulum. In the prospective cohort, lesions causing amusia mapped to a common brain network, centering on the right superior temporal cortex and clearly distinct from the network causally associated with aphasia. Lesion-induced longitudinal structural effects in the amusia circuit were confirmed as reduction of both gray and white matter volume, which correlated with the severity of amusia. We demonstrate that despite the heterogeneity of lesion locations disrupting music processing, there is a common brain network that is distinct from the language network. These results provide evidence for the distinct neural substrate of music processing, differentiating music-related functions from language, providing a testable target for noninvasive brain stimulation to treat amusia.

Acquired amusia after a right middle cerebral artery infarction - a case study.

A 62-year-old musician-MM-developed amusia after a right middle-cerebral-artery infarction. Initially, MM showed melodic deficits while discriminating pitch-related differences in melodies, musical memory problems, and impaired sensitivity to tonal structures, but normal pitch discrimination and spectral resolution thresholds, and normal cognitive and language abilities. His rhythmic processing was intact when pitch variations were removed. After 3 months, MM showed a large improvement in his sensitivity to tonality, but persistent melodic deficits and a decline in perceiving the metric structure of rhythmic sequences. We also found visual cues aided melodic processing, which is novel and beneficial for future rehabilitation practice.

Multisensory perceptual distortion including auditory distortions in Alice in Wonderland syndrome: a case report.

Alice in Wonderland syndrome (AIWS) is a rare perceptual disorder characterized mainly by perceptual distortions of visual objects and one's own body. While there are many case reports of visual and somatosensory distortions associated with AIWS, little is known about auditory distortion. Therefore, we present the case of a 22-year-old right-handed woman who described having auditory as well as visual and somatosensory distortion experiences and a family history of AIWS. The subject reported experiencing multisensory perceptual distortions, where she sees other people's faces as larger and hears their voices as louder at the same time. This particular case suggests that auditory distortion - which contributes to constructing the perception of the surrounding space and the body - may also be characterized as a perceptual symptom of AIWS.

Abnormal development of auditory responses in the inferior colliculus of a mouse model of Fragile X Syndrome.

Sensory processing abnormalities are frequently associated with autism spectrum disorders, but the underlying mechanisms are unclear. Here we studied auditory processing in a mouse model of Fragile X Syndrome (FXS), a leading known genetic cause of autism and intellectual disability. Both humans with FXS and the Fragile X mental retardation gene (Fmr1) knockout (KO) mouse model show auditory hypersensitivity, with the latter showing a strong propensity for audiogenic seizures (AGS) early in development. Because midbrain abnormalities cause AGS, we investigated whether the inferior colliculus (IC) of the Fmr1 KO mice shows abnormal auditory processing compared with wild-type (WT) controls at specific developmental time points. Using antibodies against neural activity marker c-Fos, we found increased density of c-Fos+ neurons in the IC, but not auditory cortex, of Fmr1 KO mice at P21 and P34 following sound presentation. In vivo single-unit recordings showed that IC neurons of Fmr1 KO mice are hyperresponsive to tone bursts and amplitude-modulated tones during development and show broader frequency tuning curves. There were no differences in rate-level responses or phase locking to amplitude-modulated tones in IC neurons between genotypes. Taken together, these data provide evidence for the development of auditory hyperresponsiveness in the IC of Fmr1 KO mice. Although most human and mouse work in autism and sensory processing has centered on the forebrain, our new findings, along with recent work on the lower brainstem, suggest that abnormal subcortical responses may underlie auditory hypersensitivity in autism spectrum disorders.NEW & NOTEWORTHY Autism spectrum disorders (ASD) are commonly associated with sensory sensitivity issues, but the underlying mechanisms are unclear. This study presents novel evidence for neural correlates of auditory hypersensitivity in the developing inferior colliculus (IC) in Fmr1 knockout (KO) mouse, a mouse model of Fragile X Syndrome (FXS), a leading genetic cause of ASD. Responses begin to show genotype differences between postnatal days 14 and 21, suggesting an early developmental treatment window.

Nicotinic acetylcholine receptor subunit α7-knockout mice exhibit degraded auditory temporal processing.

The CHRNA7 gene that encodes the α7-subunit of the nicotinic acetylcholine receptor (α7-nAChR) has been associated with some autism spectrum disorders and other neurodevelopmental conditions characterized, in part, by auditory and language impairment. These conditions may include auditory processing disorders that represent impaired timing of neural activity, often accompanied by problems understanding speech. Here, we measure timing properties of sound-evoked activity via the auditory brainstem response (ABR) of α7-nAChR knockout mice of both sexes and wild-type colony controls. We find a significant timing delay in evoked ABR signals that represents midbrain activity in knockouts. We also examine spike-timing properties of neurons in the inferior colliculus, a midbrain nucleus that exhibits high levels of α7-nAChR during development. We find delays of evoked responses along with degraded spiking precision in knockout animals. We find similar timing deficits in responses of neurons in the superior paraolivary nucleus and ventral nucleus of the lateral lemniscus, which are brainstem nuclei thought to shape temporal precision in the midbrain. In addition, we find that other measures of temporal acuity including forward masking and gap detection are impaired for knockout animals. We conclude that altered temporal processing at the level of the brainstem in α7-nAChR-deficient mice may contribute to degraded spike timing in the midbrain, which may underlie the observed timing delay in the ABR signals. Our findings are consistent with a role for the α7-nAChR in types of neurodevelopmental and auditory processing disorders and we identify potential neural targets for intervention.NEW & NOTEWORTHY Disrupted signaling via the α7-nicotinic acetylcholine receptor (α7-nAChR) is associated with neurodevelopmental disorders that include impaired auditory processing. The underlying causes of dysfunction are not known but a common feature is abnormal timing of neural activity. We examined temporal processing of α7-nAChR knockout mice and wild-type controls. We found degraded spike timing of neurons in knockout animals, which manifests at the level of the auditory brainstem and midbrain.

Specialized neural dynamics for verbal and tonal memory: fMRI evidence in congenital amusia.

Behavioral and neuropsychological studies have suggested that tonal and verbal short-term memory are supported by specialized neural networks. To date however, neuroimaging investigations have failed to confirm this hypothesis. In this study, we investigated the hypothesis of distinct neural resources for tonal and verbal memory by comparing typical nonmusician listeners to individuals with congenital amusia, who exhibit pitch memory impairments with preserved verbal memory. During fMRI, amusics and matched controls performed delayed-match-to-sample tasks with tones and words and perceptual control tasks with the same stimuli. For tonal maintenance, amusics showed decreased activity in the right auditory cortex, inferior frontal gyrus (IFG) and dorso-lateral-prefrontal cortex (DLPFC). Moreover, they exhibited reduced right-lateralized functional connectivity between the auditory cortex and the IFG during tonal encoding and between the IFG and the DLPFC during tonal maintenance. In contrasts, amusics showed no difference compared with the controls for verbal memory, with activation in the left IFG and left fronto-temporal connectivity. Critically, we observed a group-by-material interaction in right fronto-temporal regions: while amusics recruited these regions less strongly for tonal memory than verbal memory, control participants showed the reversed pattern (tonal > verbal). By benefitting from the rare condition of amusia, our findings suggest specialized cortical systems for tonal and verbal short-term memory in the human brain.

Comorbidity and cognitive overlap between developmental dyslexia and congenital amusia.

This study investigated whether there is a co-occurrence between developmental dyslexia and congenital amusia in adults. First, a database of online musical tests on 18,000 participants was analysed. Self-reported dyslexic participants performed significantly lower on melodic skills than matched controls, suggesting a possible link between reading and musical disorders. In order to test this relationship more directly, we evaluated 20 participants diagnosed with dyslexia, 16 participants diagnosed with amusia, and their matched controls, with a whole battery of literacy (reading, fluency, spelling), phonological (verbal working memory, phonological awareness) and musical tests (melody, rhythm and metre perception, incidental memory). Amusia was diagnosed in six (30%) dyslexic participants and reading difficulties were found in four (25%) amusic participants. Thus, the results point to a moderate comorbidity between amusia and dyslexia. Further research will be needed to determine what factors at the neural and/or cognitive levels are responsible for this co-occurrence.

Ability to process musical pitch is unrelated to the memory advantage for vocal music.

Listeners remember vocal melodies better than instrumental melodies, but the origins of the effect are unclear. One explanation for the 'voice advantage' is that general perceptual mechanisms enhance processing of conspecific signals. An alternative possibility is that the voice, by virtue of its expressiveness in pitch, simply provides more musical information to the listener. Individuals with congenital amusia provide a unique opportunity to disentangle the effects of conspecific status and vocal expressiveness because they cannot readily process subtleties in musical pitch. Forty-one participants whose musical pitch discrimination ability ranged from congenitally amusic to typical were tested. Participants heard vocal and instrumental melodies during an exposure phase, and heard the same melodies intermixed with timbre-matched foils in a recognition phase. Memory was better for vocal than instrumental melodies, but the magnitude of the advantage was unrelated to musical pitch discrimination or memory overall. The voice enhances melodic memory regardless of music perception ability, ruling out the role of pitch expressiveness in the voice advantage. More importantly, listeners across a wide range of musical ability can benefit from the privileged status of the voice.

Impaired emotional processing of chords in congenital amusia: Electrophysiological and behavioral evidence.

This study investigated whether individuals with congenital amusia, a neurogenetic disorder of musical pitch perception, were able to process musical emotions in single chords either automatically or consciously. In Experiments 1 and 2, we used a cross-modal affective priming paradigm to elicit automatic emotional processing through ERPs, in which target facial expressions were preceded by either affectively congruent or incongruent chords with a stimulus onset asynchrony (SOA) of 200 msec. Results revealed automatic emotional processing of major/minor triads (Experiment 1) and consonant/dissonant chords (Experiment 2) in controls, who showed longer reaction times and increased N400 for incongruent than congruent trials, while amusics failed to exhibit such a priming effect at both behavioral and electrophysiological levels. In Experiment 3, we further examined conscious emotional evaluation of the same chords in amusia. Results showed that amusics were unable to consciously differentiate the emotions conveyed by major and minor chords and by consonant and dissonant chords, as compared with controls. These findings suggest the impairment in automatic and conscious emotional processing of music in amusia. The implications of these findings in relation to musical emotional processing are discussed.

Auditory Localization and Spatial Release From Masking in Children With Suspected Auditory Processing Disorder.

OBJECTIVES: We sought to investigate whether children referred to our audiology clinic with a complaint of listening difficulty, that is, suspected of auditory processing disorder (APD), have difficulties localizing sounds in noise and whether they have reduced benefit from spatial release from masking. DESIGN: Forty-seven typically hearing children in the age range of 7 to 17 years took part in the study. Twenty-one typically developing (TD) children served as controls, and the other 26 children, referred to our audiology clinic with listening problems, were the study group: suspected APD (sAPD). The ability to localize a speech target (the word "baseball") was measured in quiet, broadband noise, and speech-babble in a hemi-anechoic chamber. Participants stood at the center of a loudspeaker array that delivered the target in a diffused noise-field created by presenting independent noise from four loudspeakers spaced 90° apart starting at 45°. In the noise conditions, the signal-to-noise ratio was varied between -12 and 0 dB in 6-dB steps by keeping the noise level constant at 66 dB SPL and varying the target level. Localization ability was indexed by two metrics, one assessing variability in lateral plane [lateral scatter (Lscat)] and the other accuracy in the front/back dimension [front/back percent correct (FBpc)]. Spatial release from masking (SRM) was measured using a modified version of the Hearing in Noise Test (HINT). In this HINT paradigm, speech targets were always presented from the loudspeaker at 0°, and a single noise source was presented either at 0°, 90°, or 270° at 65 dB A. The SRM was calculated as the difference between the 50% correct HINT speech reception threshold obtained when both speech and noise were collocated at 0° and when the noise was presented at either 90° or 270°. RESULTS: As expected, in both groups, localization in noise improved as a function of signal-to-noise ratio. Broadband noise caused significantly larger disruption in FBpc than in Lscat when compared with speech babble. There were, however, no group effects or group interactions, suggesting that the children in the sAPD group did not differ significantly from TD children in either localization metric (Lscat and FBpc). While a significant SRM was observed in both groups, there were no group effects or group interactions. Collectively, the data suggest that children in the sAPD group did not differ significantly from the TD group for either binaural measure investigated in the study. CONCLUSIONS: As is evident from a few poor performers, some children with listening difficulties may have difficulty in localizing sounds and may not benefit from spatial separation of speech and noise. However, the heterogeneity in APD and the variability in our data do not support the notion that localization is a global APD problem. Future studies that employ a case study design might provide more insights.

Working Memory and Extended High-Frequency Hearing in Adults: Diagnostic Predictors of Speech-in-Noise Perception.

OBJECTIVE: The purpose of this study was to identify the main factors that differentiate listeners with clinically normal or "near-normal" hearing with regard to their speech-in-noise perception and to develop a regression model to predict speech-in-noise difficulties in this population. We also aimed to assess the potential effectiveness of the formula produced by the regression model as a "diagnostic criterion" for clinical use. DESIGN: Data from a large-scale behavioral study investigating the relationship between noise exposure and auditory processing in 122 adults (30 to 57 years) was re-examined. For each participant, a composite speech-in-noise score (CSS) was calculated based on scores from three speech-in-noise measures, (a) the Speech, Spatial and Qualities of Hearing scale (average of speech items); (b) the Listening in Spatialized Noise Sentences test (high-cue condition); and (c) the National Acoustic Laboratories Dynamic Conversations Test. Two subgroups were created based on the CSS, each comprising 30 participants: those with the lowest scores and those with the highest scores. These two groups were compared for differences in hearing thresholds, temporal perception, noise exposure, attention, and working memory. They differed significantly on age, low-, high-, and extended high-frequency (EHF) hearing level, sensitivity to temporal fine structure and amplitude modulation, linguistic closure skills, attention, and working memory. A multiple linear regression model was fit with these nine variables as predictors to determine their relative effect on the CSS. The two significant predictors, EHF hearing and working memory, from this regression were then used to fit a second smaller regression model. The resulting regression formula was assessed for its usefulness as a "diagnostic criterion" for predicting speech-in-noise difficulties using Monte Carlo cross-validation (root mean square error and area under the receiver operating characteristics curve methods) in the complete data set. RESULTS: EHF hearing thresholds (p = 0.01) and working memory scores (p < 0.001) were significant predictors of the CSS and the regression model accounted for 41% of the total variance [R = 0.41, F(9,112) = 7.57, p < 0.001]. The overall accuracy of the diagnostic criterion for predicting the CSS and for identifying "low" CSS performance, using these two factors, was reasonable (area under the receiver operating characteristics curve = 0.76; root mean square error = 0.60). CONCLUSIONS: These findings suggest that both peripheral (auditory) and central (cognitive) factors contribute to the speech-in-noise difficulties reported by normal hearing adults in their mid-adult years. The demonstrated utility of the diagnostic criterion proposed here suggests that audiologists should include assessment of EHF hearing and working memory as part of routine clinical practice with this population. The "diagnostic criterion" we developed based on these two factors could form the basis of future clinical tests and rehabilitation tools and be used in evidence-based counseling for normal hearers who present with unexplained communication difficulties in noise.

Predictors of Reading Skills in Children With Listening Concerns.

OBJECTIVES: Previous research shows that children with reading disorders perform poorly on auditory processing (AP) tasks. Correlational studies have also shown significant associations between some AP tasks and word and nonword reading. There is less clear evidence for AP contributions to spelling and passage reading. The aim of this research was to extend current knowledge by investigating the association between a range of AP measures used clinically and children's reading of words, nonwords, and passages, as well as word spelling. DESIGN: Regression analyses were conducted on data from 90 children 7 to 13 years of age (58 males) with reported listening and/or reading concerns. All children had normal hearing sensitivity and were tested on AP tasks including the frequency pattern test (FPT), dichotic digits test, random gap detection test, and the masking level difference. Reading tasks included word, nonword, and passage reading. Phonologic processing, core language skills, nonverbal intelligence, memory, and attention were also measured. RESULTS: All multiregression analyses were fixed order with age and gender, nonverbal intelligence, core language, phoneme manipulation, and digits backward scores included in the model before AP measures. FPT was the only AP task that accounted for significant unique variance in word/nonword reading and nonword spelling, but not passage reading. CONCLUSIONS: The findings from this study failed to show an association between many clinically used AP measures and children's reading and spelling outcomes. Nevertheless, they reiterate the importance of evaluating FPT in children with word reading disorders. The findings justify further investigation into the role of this test when diagnosing children with reading or spelling disorders.

Contralateral suppression of otoacoustic emissions in a clinical sample of children with auditory processing disorder.

OBJECTIVE: The suppression of evoked otoacoustic emissions (EOAE) may serve as a clinical tool to evaluate the medial olivocochlear (MOC) reflex, which is thought to aid speech discrimination (particularly in noise) by selectively inhibiting cochlear amplification. The present study aimed to determine if contralateral transient evoked otoacoustic emission (TEOAE) suppression was present in a clinical sample of children with listening difficulties with and without auditory processing disorder (APD). DESIGN: A three-group, repeated measure design was used. STUDY SAMPLE: Forty three children aged 8-14 years underwent an auditory processing assessment and were divided into three groups: children with reported listening difficulties with APD, children with reported listening difficulties without APD, and children with normal hearing. APD was defined as per British Society of Audiology. RESULTS: TEOAE suppression was present in all three participant groups. No significant group, age or ear effects were observed for TEOAE suppression in dB or as a normalised index. CONCLUSION: Contralateral TEOAE suppression method could not be used as a clinical tool to identify APD in this study's participating children and did not support the hypothesised link between reduced MOC function and general listening difficulties in background noise in children with or without APD.

Spectral ripple discrimination in children with auditory processing disorder.

Objective: The purpose of this study was to examine developmental trends in spectral ripple discrimination (SRD) and to compare the performance of typically developing children to children with auditory processing disorder (APD). Study design: Cross-sectional study. Study sample: Fifteen children with APD, as well as 17 typically developing children and 14 adults reporting no listening or academic difficulties participated. Results: Typically developing children showed poor SRD thresholds compared to adults, indicating prolonged maturation of spectral shape recognition. Both typically developing children and APD children showed a maturational trend in SRD, but a General Linear Model fit to their thresholds showed that children with APD displayed SRD thresholds that were significantly poorer than those of typically developing children when controlling for age. This suggests that in APD children, SRD maturation lags behind typically developing children. Conclusion: Poor spectral ripple discrimination may explain some of the listening difficulties experienced by children with APD.

Electrophysiological characteristics in children with listening difficulties, with or without auditory processing disorder.

Objective: To determine if the auditory middle latency responses (AMLR), auditory late latency response (ALLR) and auditory P300 were sensitive to auditory processing disorder (APD) and listening difficulties in children, and further to elucidate mechanisms regarding level of neurobiological problems in the central auditory nervous system. Design: Three-group, repeated measure design. Study sample: Forty-six children aged 8-14 years were divided into three groups: children with reported listening difficulties fulfilling APD diagnostic criteria, children with reported listening difficulties not fulfilling APD diagnostic criteria and normally hearing children. Results: AMLR Na latency and P300 latency and amplitude were sensitive to listening difficulties. No other auditory evoked potential (AEP) measures were sensitive to listening difficulties, and no AEP measures were sensitive to APD only. Moderate correlations were observed between P300 latency and amplitude and the behavioural AP measures of competing words, frequency patterns, duration patterns and dichotic digits. Conclusions: Impaired thalamo-cortical (bottom up) and neurocognitive function (top-down) may contribute to difficulties discriminating speech and non-speech sounds. Cognitive processes involved in conscious recognition, attention and discrimination of the acoustic characteristics of the stimuli could contribute to listening difficulties in general, and to APD in particular.

On the definition of APD and the need for a conceptual model of terminology.

Objective: To consider the definition of auditory processing disorder (APD). Design: Narrative review and opinion piece. Study sample: Considerations of definition drawn primarily from the fields of philosophy, audition, learning and language. Results: The problem of defining APD appears genuine. Current and previous definitions of APD are nominal in nature, being both stipulative (offering explicit and arbitrary adoptions of meaning relation between words) and operational (creating rules that stipulate how the terms might apply to particular cases). Such definitions survive by consensus and perceived heuristic value in a manner that fails to achieve closure as arguments about their validity remain relative. Conclusion: A conceptual model of APD terminology is needed that considers nominal, conceptual and real definitions as well as different purposes for defining APD within professional and public domains. A framework for such a conceptual model of APD terminology is offered.

Assessment of the efferent auditory system in children with suspected auditory processing disorder: the Middle ear muscle reflex and contralateral inhibition of OAEs.

OBJECTIVE: To determine whether children aged 7 to 12 years with listening difficulties show objective evidence for efferent auditory function based on measurements of medial olivo-cochlear and middle ear muscle reflexes. DESIGN: Click-evoked otoacoustic emissions recorded with and without contralateral broadband noise and ipsilateral and contralateral tonal (1000, 2000 Hz) middle ear muscle reflex thresholds were examined. STUDY SAMPLE: 29 children diagnosed with suspected auditory processing disorder (APD) and a control group of 34 typically developing children participated in this study. RESULTS: Children with suspected APD had poorer performance on auditory processing tests than the control group. Middle ear muscle reflex thresholds were significantly higher at 2000 Hz in the suspected APD group for contralateral stimulation. MOC inhibition effects did not differ between APD and control groups. CONCLUSIONS: This research supports earlier studies showing altered acoustic reflexes in children with APD. No group differences were found for the MOC reflex measures, consistent with some earlier studies in children with APD.

Auditory event-related potentials and function of the medial olivocochlear efferent system in children with auditory processing disorders.

OBJECTIVE: The objectives were to investigate the function of central auditory pathways and of the medial efferent olivocochlear system (MOCS). DESIGN: Event-related potentials (ERP) were recorded following the delivery of the stimulus /da/ in quiet and in ipsilateral, contralateral, and binaural noise conditions and correlated to the results of the auditory processing disorders (APD) diagnostic test battery. MOCS function was investigated by adding ipsilateral, contralateral, and binaural noise to transient evoked otoacoustic emission recordings. Auditory brainstem responses and pure tone audiogram were also evaluated. STUDY SAMPLE: Nineteen children (7 to 12 years old) with APD were compared with 24 age-matched controls. RESULTS: Otoacoustic emissions and ABR characteristics did not differ between groups, whereas ERP latencies were significantly longer and of higher amplitudes in APD children than in controls, in both quiet and noise conditions. The MOCS suppression was higher in APD children. CONCLUSIONS: Findings indicate that children with APD present with neural deficiencies in both challenging and nonchallenging environments with an increase in the timing of several central auditory processes correlated to their behavioural performances. Meanwhile, their modulation of the auditory periphery under noisy conditions differs from control children with higher suppression.

Behavioral assessment of auditory processing deficits in schizophrenia: Literature review and suggestions for future research.

During the last decades, a considerable number of studies about auditory processing deficits in schizophrenia have been published, some of them using the term of Auditory Processing Disorder (APD). Due to heterogeneous methodology and inconsistent results concrete conclusions may not be straightforward. We focused on studies that used at least one behavioral test for the assessment of auditory processing in schizophrenia, in order to identify new evidence on auditory processing deficits in schizophrenia, and to consider fields for future research. 28 studies met inclusion criteria and are presented in this review. The articles were divided into three groups, those that implemented a test battery approach, those that used only Dichotic Listening (DL), those that used DL along with imaging or electrophysiology techniques. Most of the studies that implemented a test battery showed significant performance differences between patients and controls. This indicates APD presence. Due to the limited number of studies implementing a test battery, this is not conclusive. The majority of all studies that used a DL task showed that patients' performance or laterality was significantly lower than that of controls. Age, duration of illness, total and specific positive symptoms seem to affect significantly DL performance and auditory laterality. The results support the existence of various schizophrenia subgroups that differ in their auditory processing performance, and also have structural and functional specificities. Further research in the field is needed, especially studies that implement a test battery, and studies that examine possible correlations between clinical variables and auditory processing deficits.

Impaired perceptual normalization of lexical tones in Cantonese-speaking congenital amusics.

Human listeners perceive speech sounds relative to acoustic cues in context. In this study the authors examined how congenital amusia, a pitch-processing disorder, affects perceptual normalization of lexical tones according to the distribution of F0 cues in context. Sixteen Cantonese-speaking amusics and 16 controls were tested on the effects of shifting F0 level in four types of contexts on tone perception: nonspeech, reversed speech, semantically anomalous speech, and meaningful speech contexts. Performance of controls replicated previous studies, showing contrastive changes of tone perception according to the shifted F0 level of anomalous and meaningful contexts, which were native speech contexts with phonological cues to estimate a talker's tone space. Effects of nonspeech and reversed contexts were small and inconsistent, and tone perception performance varied depending on the typicality of a talker's F0 range. In contrast to controls, amusics showed reduced context effects in anomalous and meaningful contexts, but largely comparable context effects in nonspeech and reversed contexts, indicating a deficit of amusics in tone normalization through phonological cues in native speech contexts. These findings suggest that the ability to perceive speech sounds relative to acoustic cues in context is not a universal endowment, and that this ability is impaired substantially in amusics.