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Analysis of 22 kHz ultrasonic vocalization in laboratory rats: long and short calls.

There is a remarkable variation in the length of single ultrasonic calls emitted by adult rats. The duration of calls is likely to convey information for conspecifics. The goal of the present study was to analyze 22 kHz calls emitted by naive laboratory rats in response to contact with the human hand and to measure their acoustic features, with a particular emphasis on call duration. Repeated hand touch applied to the nape of the neck of rats induced ultrasonic calls, 97.4% of which were within the range of 20-29 kHz and 2.6% of which were within 44-67 kHz. Distribution of duration of 6765 calls revealed two subpopulations of 22 kHz calls: 20-300 ms calls with its peak at 150 ms and calls above 310 ms with highest values at approximately 500-600 ms without a clear peak. These two call populations were referred to as short and long calls, respectively. The short and the long vocalizations contained 80% and 100% of calls within the range of the 22 kHz frequency, respectively. The findings indicated that, in the situation studied, the 22 kHz vocalization of adult rats consists of two distinguishable subpopulation of calls: short and long with the boundary between them at 300 ms.

Animal Communication

Sound levels in rooms housing laboratory animals: an uncontrolled daily variable.

High sound levels are known to have adverse effects on the behaviour and physiology of laboratory animals, yet their acoustic environment is rarely monitored. In particular, high-frequency sounds that are above the limit of human hearing, but are well within the limits of many laboratory species (i.e., ultrasounds), are usually ignored. In this study, the acoustic environment of laboratory animals was investigated in a variety of different animal facilities. Sound pressure levels (dB SPL) were monitored for periods up to 24 h over two frequency ranges: a relatively low range (0.01-12.5 kHz), and a high range (12.5-70 kHz). While background sound levels in undisturbed situations were generally low (i.e., below 50 dB SPL), marked increases in sound levels often occurred during the working day, producing characteristic daily variations in the sound profile. Peak SPLs commonly reached values of 80-95 dB in the low-frequency range and 50-75 dB in the higher range. In most cases, sound levels were low over weekends. The results suggested that human activities were a very important source of sound in most animal facilities. In a few situations (e.g., rabbits, marmosets, dogs), the animals themselves provided a significant contribution to the acoustic environment. It is clear that the acoustic environment of laboratory animals is a daily variable that is usually uncontrolled and that may have important implications for behavioural and physiological experiments and for animal welfare.

Animal Welfare

Dissociation of androgen-dependent sociosexual behaviors in response to castration in Long-Evans rats.

Copulatory behavior and associated social behaviors such as ultrasonic vocalizations and scent marking are reduced in frequency following castration and are restored by exogenous administration of androgens. In the present study, we report the behavior of a subgroup of male Long-Evans rats in which there was a dissociation between the responses of androgen-dependent behaviors to castration. Five weeks after castration, 52% of the males tested (13 of 25) had higher 50 kHz vocalization frequencies than during precastration tests. This group continued to emit vocalizations after castration and actually increased their number of vocalizations over postcastration tests (pretest: 34.5 +/- 4.8 to week 15: 62.8 +/- 10.9/10 min test). The remaining males (n = 12) exhibited a decline in vocalizations (pretest: 29.7 +/- 5.1 to week 15: 6.5 +/- 2.7) that we typically observe in our laboratory. Both groups showed the expected decline in scent-marking frequency over the postcastration tests and were impaired in performance of copulatory behavior. Seminal vesicle and adrenal gland weights did not differ between the two groups. The 25 males were of the same genetic strain as previous animals in our laboratory except that they were born and raised in a different location prior to shipment to our laboratory. Androgens, therefore, may be only one of the possible influences mediating ultrasonic vocalizations.

Androgens

Effects of lung volume and airflow on the frequency spectrum of vesicular lung sounds.

UNLABELLED: The purpose of this study was to determine whether the vesicular lung sound frequency spectrum is affected by changes in lung volume and airflow. Nine healthy young nonsmokers were studied. The dependent variables were the points that divide the power spectrum of the vesicular lung sound into quarters (1st, 2nd and 3rd quartiles (Q1, Q2 and Q3]. Recording sites were the right upper anterior (RUL) and lower posterior (RLL) chest wall. Lung sounds were high-pass filtered at 100 Hz. To evaluate the effect of volume, lung sounds were recorded during an inspiratory vital capacity (VC) maneuver at near constant airflow rates. The spectral parameters were determined at each sixth of the VC. To assess the effects of airflow, 5 of the subjects breathed from resting lung volume at peak inspiratory airflows of between 1 and 3.0 L/sec for a total of 16 breaths each and the frequency parameters of the lung sounds occurring during peak inspiratory airflows were determined. RESULTS: Volume effects: only at the RUL was there a small but significant decrease in all three parameters with increasing lung volume. Airflow effects: all parameters were independent of airflow except for a weakly positive relationship (r = 0.285, P less than 0.05) for Q3 at the RUL location. Individually, there were weakly significant trends in three of the five subjects. These data suggest that the frequency composition of the vesicular lung sound in groups of healthy adults is not systematically affected by changes in lung volume or airflow.

Adult

Temporal speech characteristics associated with anterior left hemisphere cortical and subcortical lesions: a preliminary case study report.

There is disagreement in the literature regarding the characteristics of cortical and subcortical forms of aphasia. M. L. Albert, H. Goodglass, N. A. Helm, A. B. Rubens, and M. P. Alexander (Clinical Aspects of Dysphasia, Vienna/New York: Springer-Verlag, 1980) state that the two are indistinguishable. The opposing view has been presented by M. A. Naeser, M. P. Alexander, N. Helm-Estabrook, H. L. Levine, S. A. Laughlin, and N. Geschwind (Archives of Neurology, 39, 1982) and A. R. Damasio, H. Damasio, M. Rizzo, N. Varney, and F. Gersh (Archives of Neurology, 39, 15-20, 1982), who suggest that subcortical aphasias are not adequately described by the classic, cortical aphasia descriptions. In this study the temporal speech characteristics of a neurologically normal individual, an aphasic patient with anterior cortical and subcortical lesion locus, and a second aphasic patient, whose lesion was limited to anterior subcortical structures, were studied utilizing acoustic analysis of isolated word and phrase productions. The results of this investigation showed individually unique temporal patterns in the speech of each of the subjects studied. While the results must be interpreted conservatively due to the small number of cases described, they do provide tentative support for the Naeser et al. (1982) and Damasio et al. (1982) position. Furthermore, the results demonstrate the potential value of combining sensitive radiographic and acoustic measures in future studies that seek to compare cortical and subcortical forms of aphasia.

Aphasia

Disturbed coarticulation in apraxia of speech: acoustic evidence.

The results of a recent perceptual study (W. Ziegler & D. von Cramon, 1985, Anticipatory coarticulation in a patient with apraxia of speech. Brain and Language 26, 117-130) provided evidence for disturbed coarticulation in verbal apraxia. Further support for this finding is now provided by acoustic analyses. Formant frequencies and LP reflection coefficients were chosen to assess anticipatory vowel-to-vowel coarticulation and vowel anticipation in stop consonants, respectively. These parameters revealed a lack of coarticulatory cohesion in the speech of a patient suffering from verbal apraxia, explainable by a consistent delay in the initiation of anticipatory vowel gestures. The findings are discussed with respect to prosodic features and to theoretical and clinical concepts of verbal apraxia.

Adult

The neurological substrates for prosodic aspects of speech.

The ability to comprehend and produce the stress contrast between noun compounds and noun phrases (e.g., greenhouse vs. green house) was examined for 8 nonfluent aphasics, 7 fluent aphasics, 7 right hemisphere damaged (RHD) patients, and 22 normal controls. The aphasics performed worse than normal controls on the comprehension task, and the RHD group performed as well as normals. The ability to produce stress contrasts was tested with a sentence-reading task; acoustic measurements revealed that no nonfluent aphasic used pitch to distinguish noun compounds from phrases, but two used duration. All but one of the RHD patients and all but one of the normals produced pitch and/or duration cues. These results suggest that linguistic prosody is processed by the left hemisphere and that with brain damage the ability to produce pitch and duration cues may be dissociated at the lexical level.

Aged

The role of the right hemisphere in the production of linguistic stress.

Recent research has proposed a general prosodic disturbance associated with right hemisphere damage (RHD), one encompassing both affective and linguistic functions. The present study attempted to explore whether the ability to produce linguistic prosody was impaired in this patient population. Productions of phonemic stress tokens (e.g., Re'dcoat vs. red coa't) as well as examples of contrastive stress, or sentential emphasis (e.g., Sam hated the movie), were elicited from eight male speakers with unilateral right hemisphere CVAs and seven male control subjects. Two types of analyses were conducted on these utterances. Acoustic analysis focused on the correlates associated with word stress, namely changes in amplitude, duration, and fundamental frequency. The perceptual saliency of emerging cues to stress was also examined by presentation of test tokens to phonetically trained listeners for identification of stress placement. The patients as a group produced fewer acoustic cues to stress compared to the normal subjects, but no statistical differences were found between groups for either stress at the phrase level or at the sentence level. In the perceptual analysis, stress produced by the patient group was judged to be less salient than that for the normal group, although a high degree of variability was evident in both populations. The data suggest a spared processing mechanism for linguistic prosody in RHD speakers, thus mitigating against the view of a general dysprosody tied to RHD.

Adult

Acoustic analysis of affective prosody during right-sided Wada Test: a within-subjects verification of the right hemisphere's role in language.

A within-subjects study of the affective characteristics of voice was carried out in patients undergoing a Wada Test (WT). All patients became densely aphasic after the left-sided WT and lost the ability to impart affect into speech after the right-sided WT. The affective changes in voice induced by the Wada test were acoustically analyzed by computer-assisted techniques and compared to data obtained pre-Wada and post-Wada. The statistical results, using a one-way analysis of variance for repeated measures, confirmed robustly the current view that the right hemisphere modulates dominantly the affective components of language. The results are also evaluated in light of recent clinical and acoustical data regarding the organization of language in speakers of tone languages, thus, allowing the authors to address issues concerning universal principles of brain-language-behavioral relationships.

Adult

Language production in Parkinson's disease: acoustic and linguistic considerations.

The hypokinetic dysarthria of Parkinson's disease (PD) has been described extensively. In contrast, patterns of hesitation and the language structure in spontaneous speech of the PD patient have not been investigated, although several studies have shown language-related abnormalities in word naming, word generation, and verbal recall. In the present study, 10 male Parkinson's patients and 10 normal male speakers were compared in a reading and spontaneous speaking paradigm for acoustic and linguistic features. Among acoustic measures, fundamental frequency and relative intensity differentiated PD from control subjects, consistent with reported features of hypokinetic dysarthria. The striking observations among linguistic measures differentiating PD from control subjects were an increase in the number of (a) silent hesitations per minute, (b) abnormally long silent hesitations, (c) words per silent hesitation, (d) open class phrases, and (e) optional open phrases per speech sample, and a decrease in the number of modalizations and interjections. An increase in the number of filled hesitations occurring per minute, as well as a decrease in syntactic complexity separated moderate from mild Parkinson's patients. Our interpretation of the data favors the hypothesis that changes in the structure of spontaneous language production with increasing severity of dysarthria reflect PD patients' adaptation to their disease.

Dysarthria

The role of callosal connections in speech prosody.

A 39-year-old right-handed woman suffered an aneurysmal hemorrhage damaging the anterior four-fifths of the corpus callosum as shown on MRI. Computer-aided acoustical analyses of fundamental frequency (Fo) contours and durational patterns were performed on emotive and nonemotive utterances at 4 weeks, 4 months, and 1 year postsurgery. The patient read sentences in each of five tones (happy, sad, angry, neutral, questioning) or with emphasis on certain words. She showed little Fo distinction with intended mood at 4 weeks, but her performance improved over time. This improvement in speech production was accompanied by an improvement in perceptual judgments of her intended tone by six normal listeners. Fo patterns characteristic of emphatic stress and question forms were found at all test periods, but again improved with time. Durationally, the patient showed appropriate emotive and nonemotive distinctions on most sentences. These results provide acoustic evidence that interhemispheric connections via the corpus callosum are important to proper Fo programming, especially emotive distinctions. The results suggest that the right hemisphere contributes to Fo programming but, following callosal damage, such programming can later be performed by the left hemisphere.

Adult

Anticipatory coarticulation in aphasia: acoustic and perceptual data.

Two experiments investigated speech motor planning in aphasia by contrasting the degree of labial and lingual anticipatory coarticulation evident in normal subjects' speech with that found in the speech of aphasic subjects. In the first experiment, Linear Predictive Coding (LPC) analyses were conducted for the initial consonants of CV [si su ti tu ki ku] and CCV [sti stu ski sku] productions by 6 normal and 10 aphasic (5 anterior, 5 posterior) subjects. For normal subjects' productions, reliable coarticulatory shift was found for almost all measurements, indicating that acoustic correlates for anticipatory coarticulation obtain for [s], [t], and [k] in a prevocalic environment, as well as when [s] is the initial consonant of a CCV syllable. The data for the aphasic subjects were statistically indistinguishable from those of the normal subject group, and there were no differences noted as a function of aphasia type. In the second experiment, a subset of the consonantal stimuli produced by the normal and aphasic subjects was presented to a group of 10 naive listeners for a vowel identification task. Listeners were able to identify the productions of all subjects at a level well above chance. In addition, small but statistically significant Group differences were observed, with the [sV], [skV], and [tV] productions by anterior aphasics showing significantly lower perceptual scores than those of normal subjects.

Aged

A characterization of the prosodic loss in Parkinson's disease.

Prosodic contours in the verbal output of 30 patients with Idiopathic Parkinson's disease were contrasted to those of fifteen age-, sex-, and educationally matched normal subjects. All subjects were tested for language disorder, dementia, depression, and the comprehension of linguistic prosody. The striking disorder of prosody in Parkinson's disease relates to motor control, not to a loss of the linguistic knowledge required to make prosodic distinctions. It appears that prosody, language and the motor planning of speech are integrated at a basal ganglia level.

Aged

Characterizing sentence intonation in a right hemisphere-damaged population.

Current production studies present a mixed view of right hemisphere-damaged (RHD) patients' ability to produce normal sentence intonation. The present study characterized the sentence intonation of RHD patients, focusing on a greater number of acoustic parameters than past works, and relying on more naturally elicited speech samples through use of a story completion task. Eight RHD speakers and seven nonneurological control subjects produced declarative and imperative sentences as well as yes-no and wh-questions. Slope of F0 change, linearity of pitch contour, and variance of F0 points were calculated for each utterance as a whole, as well as for the preterminal and the terminal contour separately. RHD contours were less linear and flatter in F0 decline than normal controls for the declarative sentences. The patients' yes-no questions also differed from normal productions, displaying smaller F0 dispersion around a mean F0. Preterminal range values were more restricted for patients' utterances of yes-no questions, while terminal properties between groups differed for three of the four sentence types examined. The present results suggest some disturbance in the patients' ability to manipulate fundamental frequency across sentential domains. These data are discussed in terms of current theories of a general dysprosody in RHD patients.

Brain

Dysprosody in Broca's aphasia: a case study.

A detailed acoustic analysis of timing, intensity, and fundamental frequency (F0) at different levels of linguistic structure was conducted on the speech output of a Broca's aphasic who was a native speaker of Thai. Timing was measured with respect to syllables, phrases, and sentences in connected speech. Intensity variation at the sentence level was measured in connected speech. F0 variation associated with the five Thai tones was measured in both isolated words and connected speech. Results indicated that timing was differentially impaired depending upon complexity of articulatory gesture and size of the linguistic structure. Timing, as well as intensity, was aberrant at the sentence level. In contrast, F0 contours of the five tones were spared at all levels of linguistic structure. Findings are interpreted to support the view that dysprosody in Broca's aphasia is more applicable to speech timing than to F0.

Aphasia