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PubMed2004

Voice acoustical measurement of the severity of major depression.

A number of empirical studies have documented the relationship between quantifiable and objective acoustical measures of voice and speech, and clinical subjective ratings of severity of Major Depression. To further explore this relationship, speech samples were extracted from videotape recordings of structured interviews made during the administration of the 17-item Hamilton Depression Rating Scale (HDRS; ). Pilot data were obtained from seven subjects (five males, two females) from videotapes that have been used to train expert raters on the administration and scoring of the HDRS. Several speech samples were isolated for each subject and processed to obtain the acoustic measurements. Acoustic measures were selected on the basis that they were correlated with HDRS ratings of symptom severity as seen under ideal voice recording conditions in previous studies. Our findings corroborate earlier reports that speaking rate is well correlated (negatively) with HDRS scores, with a strong correlation and nearly significant trend seen for the measure of pitch variability. A moderate pairwise correlation between percent pause time and HDRS score was also revealed, although this relationship was not statistically significant. The results from this cross-sectional study further demonstrate the ability of voice and speech signal analyses to objectively track severity of depression. In the present case, it is suggested that this relationship is robust enough to be found despite the less than ideal recording conditions and equipment used during the original videotape recording. Voice acoustical analyses may provide a powerful compliment to the standard clinical interview for depression. Use of such measures increases the range of techniques that are available to explore the neurobiological substrates of Major Depression, its treatment, and the dynamic interplay of the systems that govern the motor, cognitive, and emotional aspects of speech production.

Adult↗
PubMed2004

Impaired pitch production and preserved rhythm production in a right brain-damaged patient with amusia.

Pre- and postmorbid singing of a patient with amusia due to a right-hemispheric infarction was analyzed acoustically. This particular patient had a premorbid tape recording of her own singing without accompaniment. Appropriateness of pitch interval and rhythm was evaluated based on ratios of pitch and duration between neighboring notes. The results showed that melodic contours and rhythm were preserved but individual pitch intervals were conspicuously distorted. Our results support a hypothesis that pitch and rhythm are subserved by independent neural subsystems. We concluded that action-related acoustic information for controlling pitch intervals is stored in the right hemisphere.

Auditory Perception↗
PubMed2005

Speech-sound duration processing in a second language is specific to phonetic categories.

The mismatch negativity (MMN) component of the auditory event-related potential was used to determine the effect of native language, Russian, on the processing of speech-sound duration in a second language, Finnish, that uses duration as a cue for phonological distinction. The native-language effect was compared with Finnish vowels that either can or cannot be categorized using the Russian phonological system. The results showed that the duration-change MMN for the Finnish sounds that could be categorized through Russian was reduced in comparison with that for the Finnish sounds having no Russian equivalent. In the Finnish sounds that can be mapped through the Russian phonological system, the facilitation of the duration processing may be inhibited by the native Russian language. However, for the sounds that have no Russian equivalent, new vowel categories independent of the native Russian language have apparently been established, enabling a native-like duration processing of Finnish.

Child↗
PubMed2005

Auditory backward masking deficits in children with reading disabilities.

Studies evaluating temporal auditory processing among individuals with reading and other language deficits have yielded inconsistent findings due to methodological problems () and sample differences. In the current study, seven auditory masking thresholds were measured in fifty-two 7- to 10-year-old children (26 diagnosed with reading disability [RD], 26 without reading disability). Hierarchic multiple regression analyses indicated that RD status predicted performance only in the backward-bandpass noise (p<.05) and backward notched-noise conditions (p<.05), suggesting both temporal and spectral auditory processing deficits. These results suggest that any auditory deficit associated with RD may be more complex than previously hypothesized.

Attention↗
PubMed2006

Mismatch negativity elicited by tones and speech sounds: changed topographical distribution in aphasia.

This study used the event-related brain potential mismatch negativity (MMN) to investigate preconscious discrimination of harmonically rich tones (differing in duration) and consonant-vowel syllables (differing in the initial consonant) in aphasia. Eighteen Norwegian aphasic patients, examined on average 3 months after brain injury, were compared to 11 healthy controls. The main finding was a difference in topographic distribution of the MMN: the aphasia group showed a less lateralized and centralized topographic pattern especially to CV syllables, which is consistent with a reduced temporal lobe processing contribution and an increased right hemisphere activation. No correlations between MMN amplitude and aphasia test results were found.

Acoustic Stimulation↗
PubMed2006

The distribution of substance P and met-enkephalin in vocal control nuclei among oscine species and its relation to song complexity.

Substance P (SP) and methionine-enkephalin (ENK) have been reported to appear in song control nuclei of oscine species. However, it remains unknown whether or not SP and ENK location in song control nuclei is correlated with song behavior. To address this issue, the present study first measured two variables for song complexity, i.e., song repertoire sizes, and syllable repertoire sizes in 11 oscine species. Then, we examined the distribution of SP and ENK in four control nuclei, two in the motor pathway, i.e., HVC and the robust nucleus of arcopallium (RA), and the other two in the forebrain pathway, i.e., Area X and the lateral magnocellular nucleus of the anterior nidopallium (LMAN). Finally, we measured the relative amounts of immunoreactivity for SP and ENK in song control nuclei, and tested whether they were correlated with song complexity. Our results showed that: (1) SP and ENK were broadly distributed in the song control nuclei of studied species. However, SP immunohistochemistry was more robust in comparison with ENK, and SP is generally more abundant in the two song learning nuclei than those in the two song producing ones; (2) SP and ENK staining patterns in song control nuclei did not show any obvious phylogenetic relationship among studied oscine species; (3) there was a significant correlation between the relative amounts of immunoreactivity for SP and the song and syllable repertoire sizes. Our results suggest that SP or ENK might be involved in song behavior, such as birdsong learning or memory.

Animals↗
PubMed2006

Dissimilarities in the vocal control over communication and echolocation calls in bats.

Bats, like other mammals, use communication calls for social interaction, but rely at the same time on sophisticated echolocation systems for orientation and prey capture. Both call types are of laryngeal origin, but can be distinguished on the basis of their spectral and temporal features and apparently their functional involvement as well. Although they share a common final motor pathway, there is evidence that separate vocally active brainstem areas are involved in the functional control of communication and echolocation calls. This review summarizes findings that support the above assumption, and focus on the functional involvement of the periaqueductal gray, the paralemniscal area, and the nucleus of the brachium of the inferior colliculus, in differentiated vocal control.

Animals↗
PubMed2004

A method for identifying sounds used in the classification of alarm calls.

In this study, we present a methodology that identifies acoustic units in Gunnison's prairie dog alarm calls and then uses those units to classify the alarm calls and bouts according to the species of predator that was present when the calls were vocalized. While traditional methods measure specific acoustic parameters in order to describe a vocalization, our method uses the variation in the internal structure of a vocalization to define possible information structures. Using a simple representation similar to that used in human speech to identify vowel sounds, a software system was developed that uses this representation to recognize acoustic units in prairie dog alarm calls. These acoustic units are then used to classify alarm calls and their associated bouts according to the species of predator that was present when the alarm calls were vocalized. Identification of bouts with up to 100% accuracy was obtained. This work represents a first step toward revealing the details of how information is encoded in a complex nonhuman communication system. Furthermore, the techniques discussed in this paper are not restricted to a database of prairie dog alarm calls. They could be applied to any animal whose vocalizations include multiple simultaneous frequencies.

Acoustics↗
PubMed2005

Call-based species recognition in black-capped chickadees.

Species recognition is essential for efficient communication between conspecifics. For this to occur, species information must be unambiguously encoded in the repertoire of each species' vocalizations. Until now, the study of species recognition in songbirds has been focused mainly on male songs and male territorial behaviour. Species recognition of other learned vocalizations, such as calls, have not been explored, and could prove useful as calls are used in a wider range of contexts. Here, we present an experimental field study investigating the coding of species information in a learned vocalization, the 'chick-a-dee' call of the black-capped chickadee (Poecile atricapillus). By modifying natural calls in both temporal and spectral domains and by observing the vocal responses of black-capped chickadees following the playback of these modified calls, we demonstrate that species recognition in chickadees relies on several acoustic features including syntax, frequency modulation, amplitude modulation, and to a lesser extent, call rhythmicity and frequency range.

Animal Communication↗
PubMed2006

Can humans discriminate between dogs on the base of the acoustic parameters of barks?

In this study we tested the often suggested claim that people are able to recognize their dogs by their barks. Earlier studies in other species indicated that reliable discrimination between individuals cannot be made by listening to chaotically noisy vocalizations. As barking is typically such a chaotic noisy vocalization, we have hypothesized that reliable discrimination between individuals is not possible by listening to barks. In this study, playback experiments were conducted to explore (1) how accurately humans discriminate between dogs by hearing only their barks, (2) the impact of the eliciting context of calls on these discrimination performances, and (3) how much such discrimination depends on acoustic parameters (tonality and frequency of barks, and the intervals between the individual barks). Our findings were consistent with the previous studies: human performances did not pass the empirical threshold of reliable discrimination in most cases. But a significant effect of tonality was found: discrimination between individuals was more successful when listeners were listening to low harmonic-to-noise ratio (HNR) barks. The contexts in which barks were recorded affected significantly the listeners' performances: if the dog barked at a stranger, listeners were able to discriminate the vocalizations better than if they were listening to sounds recorded when the dog was separated from its owner. It is rendered probable that the bark might be a more efficient communication system between humans and dogs for communicating the motivational state of an animal than for discrimination among strange individuals.

Acoustics↗
PubMed2006

Learning of auditory equivalence classes for vowels by rats.

Four male Long-Evans rats were trained to discriminate between synthetic vowel sounds using a GO/NOGO response choice task. The vowels were characterized by an increase in fundamental frequency correlated with an upward shift in formant frequencies. In an initial phase we trained the subjects to discriminate between two vowel categories using two exemplars from each category. In a subsequent phase the ability of the rats to generalize the discrimination between the two categories was tested. To test whether rats might exploit the fact that attributes of training stimuli covaried, we used non-standard stimuli with a reversed relation between fundamental frequency and formants. The overall results demonstrate that rats are able to generalize the discrimination to new instances of the same vowels. We present evidence that the performance of the subjects depended on the relation between fundamental and formant frequencies that they had previously been exposed to. Simple simulation results with artificial neural networks could reproduce most of the behavioral results and support the hypothesis that equivalence classes for vowels are associated with an experience-driven process based on general properties of peripheral auditory coding mixed with elementary learning mechanisms. These results suggest that rats use spectral and temporal cues similarly to humans despite differences in basic auditory capabilities.

Animals↗
PubMed2004

The effects of early maternal deprivation on auditory information processing in adult Wistar rats.

BACKGROUND: There is now ample evidence that schizophrenia is due to an interaction between genetic and (early) environmental factors which disturbs normal development of the central nervous system and ultimately leads to the development of clinical symptoms. Recently, we showed that a single 24-hour period of maternal deprivation of rat pups at postnatal day 9 leads to a disturbance in prepulse inhibition, similar to what is seen in schizophrenia. The present set of experiments was designed to further characterize the information processing deficits of maternally deprived Wistar rats. METHODS: Wistar rats were deprived from their mother for 24 hours on postnatal day 9. At adult age, rats were tested in the acoustic startle paradigm for prepulse inhibition and startle habituation. Rats were also tested in the evoked potentials paradigm for auditory sensory gating. RESULTS: The results show that maternal deprivation led to a reduction in acoustic startle habituation and auditory sensory gating in adult rats. Moreover, maternal deprivation disrupted prepulse inhibition but only when the prepulses were given shortly (50-100 milliseconds) before the startle stimulus. At longer intervals (250-1000 milliseconds), no effect was seen. CONCLUSIONS: The implications for the model and the development of disturbances in information processes are discussed.

Acoustic Stimulation↗
PubMed2005

Effects of background and prepulse characteristics on prepulse inhibition and facilitation: implications for neuropsychiatric research.

BACKGROUND: Both prepulse inhibition (PPI) and prepulse facilitation (PPF) deficits have been reported in schizophrenia patients, but the use of different experimental parameters across laboratories makes direct comparisons of results difficult. We assessed the effects of different parameters on PPI and PPF in normal subjects. METHODS: Eyeblink startle was measured in 14 healthy male subjects, using 115 dB[A] white noise startle pulses and 86 dB[A] prepulses. Analyses compared the effects of: 1) background noise level (ambient 54 vs. 70 dB[A]) on PPI and PPF, 2) prepulse duration (discrete 20 msec vs. continuous) on PPF, 3) prepulse frequency (1000 Hz vs. white noise) on PPI and PPF, and 4) prepulse interval (2000 vs. 4500 msec) on PPF. RESULTS: Compared to an experimentally delivered 70 dB[A] background, ambient 54 dB[A] background led to significantly more PPI (with discrete white noise prepulses), and more PPF (with continuous prepulses). Continuous and longer (4500 msec) prepulses induced more PPF than did discrete and shorter (2000 msec) prepulses. CONCLUSIONS: Paradigmatic differences appear likely to be responsible for divergent findings in studies of PPI and PPF in normal and schizophrenia subjects. The present study should guide investigators in the selection of parameters for assessing PPI and PPF in studies of normal subjects and schizophrenia patients. Attention to the 4 factors of 1) background noise, 2) prepulse duration, 3) frequency, and 4) interval will facilitate comparability of results across different laboratories, especially when using PPI/PPF in schizophrenia research as neural substrate probes, as biomarkers, and as endophenotypes.

Acoustic Stimulation↗
PubMed2006

Language processing and human voice perception in schizophrenia: a functional magnetic resonance imaging study.

BACKGROUND: Neuroimaging studies have demonstrated either reduced left-lateralized activation or reversed language dominance in schizophrenia. These findings of left hemispheric dysfunction could be attributed to language processing tasks, which activate mainly left hemispheric function. Recent functional magnetic resonance imaging studies reported right-lateralized temporal activation by human voice perception, but few studies have investigated activation by human voice in schizophrenia. We aimed to clarify the cerebral function of language processing in schizophrenia patients by considering cerebral activation of human voice perception. METHODS: Fourteen right-handed schizophrenia patients and 14 right-handed controls with matched handedness, sex, and education level were scanned by functional magnetic resonance imaging while listening to sentences (SEN), reverse sentences (rSEN), and identifiable non-vocal sounds (SND). RESULTS: Under the SEN-SND and SEN-rSEN contrasts including language processing, patients showed less activation of the left hemisphere than controls in the language-related fronto-tempo-parietal region, hippocampus, thalamus and cingulate gyrus. Under the rSEN-SND contrast including human voice perception, patients showed less activation than controls in the right-lateralized temporal cortices and bilateral posterior cingulate. CONCLUSIONS: Our results indicate that schizophrenia patients have impairment of broader bilateral cortical-subcortical regions related to both the semantic network in the left hemisphere and the voice-specific network in the right hemisphere.

Adult↗
PubMed2006

Effects of prepulse intensity, duration, and bandwidth on perceived intensity of startling acoustic stimuli.

Intense abrupt stimuli can elicit a startle reflex; a weak "prepulse" 30-300 ms earlier can reduce both startle and perceived stimulus intensity. Prepulse inhibition (PPI) of startle, an operational measure of sensorimotor gating, is used to understand brain disorders characterized by gating deficits. Compared to startle, PPI of perceived stimulus intensity (PPIPSI) may provide information that is distinct, and easier to acquire and analyze. To develop this experimental measure, we examined PPIPSI under different stimulus conditions. Both PPI and PPIPSI exhibited a non-linear relationship to prepulse intensity, with prepulses 15 dB(A) above background causing maximal inhibition of both measures. A 50 ms broadband noise prepulse produced maximal PPI and PPIPSI, whereas 5 and 20 ms pure tone prepulses produced maximal PPIPSI and PPI, respectively. PPIPSI is a robust, parametrically sensitive and "low tech" measure of sensory gating that may become a valuable tool for understanding the biology of certain mental disorders.

Acoustic Stimulation↗
PubMed2006

Musically induced arousal affects pain perception in females but not in males: a psychophysiological examination.

The present study investigated affective and physiological responses to changes of tempo and mode in classical music and their effects on heat pain perception. Thirty-eight healthy non-musicians (17 female) listened to sequences of 24 music stimuli which were variations of 4 pieces of classical music. Tempo (46, 60, and 95 beats/min) and mode (major and minor) were manipulated digitally, all other musical elements were held constant. Participants rated valence, arousal, happiness and sadness of the musical stimuli as well as the intensity and the unpleasantness of heat pain stimuli which were applied during music listening. Heart rate, respiratory rate and end-tidal PCO(2) were recorded. Pain ratings were highest for the fastest tempo. Also, participants' arousal ratings, their respiratory rate and heart rate were accelerated by the fastest tempo. The modulation of pain perception by the tempo of music seems to be mediated by the listener's arousal.

Adolescent↗
PubMed2004

Changes in emotional tone and instrumental timbre are reflected by the mismatch negativity.

The present study examined whether or not the brain is capable to preattentively discriminate tones differing in emotional expression or instrumental timbre. In two event-related potential (ERP) experiments single tones (600 ms) were presented which had been rated as happy or sad in a pretest. In experiment 1, 12 non-musicians passively listened to tone series comprising a frequent (standard) single musical tone played by a violin in a certain pitch and with a certain emotional connotation (happy or sad). Among these standard tones deviant tones differing in emotional valence, either in instrumental timbre or in pitch were presented. All deviants generated mismatch negativity (MMN) responses. The MMN scalp topography was similar for all of the three deviants but latency was shorter for pitch deviants than for the other two conditions. The topography of the mismatch responses was indistinguishable. In a second experiment, subjects actively detected the deviant tones by button press. All detected deviants generated P3b waves at parietal leads. These results indicate that the brain is not only able to use simple physical differences such as pitch for rapid preattentive categorization but can also perform similar operations on the basis of more complex differences between tones of the same pitch such as instrumental timbre and the subtle timbral differences associated with different emotional expression. This rapid categorization may serve as a basis for the further fine-grained analysis of musical (and other) sounds with regard to their emotional content.

Acoustic Stimulation↗
PubMed2005

Encoding of pitch in the human brainstem is sensitive to language experience.

Neural processes underlying pitch perception at the level of the cerebral cortex are influenced by language experience. We investigated whether early, pre-attentive stages of pitch processing at the level of the human brainstem may also be influenced by language experience. The human frequency following response (FFR), reflecting sustained phase-locked activity in a population of neural elements, was used to measure activity within the rostral brainstem. FFRs elicited by four Mandarin tones were recorded from native speakers of Mandarin Chinese and English. Pitch strength (reflecting robustness of neural phase-locking at the pitch periods) and accuracy of pitch tracking were extracted from the FFRs using autocorrelation algorithms. These measures revealed that the Chinese group exhibits stronger pitch representation and smoother pitch tracking than the English group. Consistent with the pitch data, FFR spectral data showed that the Chinese group exhibits stronger representation of the second harmonic relative to the English group across all four tones. These results cannot be explained by a temporal pitch encoding scheme which simply extracts the dominant interspike interval. Rather, these results support the possibility of neural plasticity at the brainstem level that is induced by language experience that may be enhancing or priming linguistically relevant features of the speech input.

Acoustic Stimulation↗