Purpose Advances in neurobiology are providing new opportunities to investigate the neurological systems underlying motor speech control. This study explores the perceptual characteristics of the speech of three genotypes of spino-cerebellar ataxia (SCA) as manifest in four different speech tasks. Methods Speech samples from 26 speakers with SCA were perceptually rated by experienced listeners. The genotypes were: SCA1, SCA5, or SCA6. The speech tasks were: diadochokinesis, word repetition, sentence reading, and picture description. The speech samples were rated using two sets of dimensions characterized as primary (e.g., articulation, rate, and rhythm) or secondary (e.g., imprecise consonants, excess and equal stress, and harsh voice). Results On primary dimensions, SCA6 was the most impaired generally. Articulation was the most severely affected dimension and the diadochokinesis task was most effective in revealing speech impairments. On secondary dimensions, picture description was the task most likely to produce abnormal speech. The SCA groups shared articulatory problems but differed with respect to abnormal voice features. Conclusions These results support previous characterizations of ataxic dysarthria, and provide further information about the speech characteristics of genetic subtypes. Task demands affect perceptual ratings. Voice characteristics may be key to differentiating ataxic subtypes. As the genetic disorders that affect speech become better understood, more detailed characterizations of motor control systems should emerge.

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The relationship between speech and singing in cerebral function is not fully understood. The effects of focal brain damage on pitch, timing, and rhythm in speech and singing were retrospectively investigated in 2 persons diagnosed with dysprosodic speech following cerebral vascular accidents; both were experienced singers. Participant 1 suffered a large right hemisphere infarct encompassing frontal, parietal, and temporal lobes extending partly into subcortical structures, and Participant 2 sustained a right-sided ischemic subcortical lesion, affecting globus pallidus, caudate and medial putamen. Pitch and timing in lexical contrasts were acoustically analyzed, rhythm and pitch in spontaneous speech were quantified, and accuracies of pitch and rhythm in familiar songs were measured acoustically and rated by listeners. Both participants produced lexical contrasts with disordered pitch but normal timing. Pitch was abnormal in spontaneous speech in both cases, but in singing, pitch was impaired in Participant 1, not in Participant 2. Speech rhythm deviated from normal values for Participant 1 but not for Participant 2, whereas rhythm in singing was accurate for both persons. These studies reveal dissociations between pitch, rhythm, and timing in speech versus singing, suggesting that talking and singing arise from disparate neurological systems. Better understanding of these dissociations may lead to improved models of speaking and singing in cerebral function and may assist in assessment and treatment of dysprosody and amusia.

Ditropic sentences are utterances that convey either a literal or an idiomatic meaning (e.g., It broke the ice). This study investigated listener’s ability to discriminate between literal or idiomatic meanings and examined the acoustic features contributing to this distinction. Ten ditropically ambiguous Korean sentences were audio-recorded by four native speakers of Korean. Each utterance was produced twice with either a literal or idiomatic meaning. Fifteen native Korean subjects listened to a randomized presentation of these utterances singly and in pairs without other context and identified each as literal or idiomatic. Listeners successfully discriminated the intended idiomatic or literal meanings (singletons = 70.65%, pairs = 75.67%). These results were consistent with those of Van Lancker and Canter [(1981)] for English ditropic sentences. Each utterance was acoustically analyzed in terms of means and variations in fundamental frequency, duration, and intensity. Analyses of variance revealed significantly longer durations and greater variation in syllable duration for literal than idiomatic sentences, whereas idiomatic sentences were characterized by significantly greater variation in intensity than literal sentences. Some prosodic cues for Korean differed from those found previously for English [Van Lancker et al. (1981)] and French [Abdelli-Baruh et al. (2007)]. These results further understanding of use of prosody in sentential linguistic contrasts.