SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The problem of distinguishing particular sounds, such as conversation, against a background of irrelevant noise is a matter of common experience. Psychologists have studied it for some 40 years, but it is only comparatively recently that computer modelling of the phenomenon has been attempted. This article reviews progress made, possible practical applications, and prospects for the future.
Area X, a large sexually dimorphic nucleus in the avian ventral forebrain, is part of a highly discrete system of interconnected nuclei that have been implicated in either song learning or adult song production. Previously, this nucleus has been included in the song system because of its substantial connections with other vocal control nuclei, and because its volume is positively correlated with the capacity for song. In order to directly assess the role of Area X in song behavior, this nucleus was bilaterally lesioned in both juvenile and adult zebra finches, using ibotenic acid. We report here that lesioning Area X disrupts normal song development in juvenile birds, but does not affect the production of stereotyped song by adult birds. Although juvenile-lesioned birds were consistently judged as being in earlier stages of vocal development than age-matched controls, they continued to produce normal song-like vocalizations. Thus, unlike the lateral magnocellular nucleus of the anterior neostriatum, another avian forebrain nucleus implicated in song learning, Area X does not seem to be necessary for sustaining production of juvenile song. Rather, the behavioral results suggest Area X is important for either the acquisition of a song model or the improvement of song through vocal practice.
Although songbirds rely on auditory input for normal song development, many species eventually attain adult song patterns that are thought to be maintained without reference to auditory feedback. In such species, it is believed that a central motor program for song is established when the stereotyped adult song pattern is achieved. However, we report here that in the Australian zebra finch, stereotyped song patterns gradually change in adult males following bilateral cochlear removal. By 16 weeks after surgery, deaf birds accurately reproduced only 36% of the song syllables produced prior to surgery. Moreover, on average, the phonology of over 50% of the syllables produced by deaf birds was either only slightly similar or unlike the phonology of any syllable produced prior to surgery. In contrast, control birds accurately retained over 90% of their syllables over a comparable time period and less than 5% of their syllables was unmatched or only slightly similar in phonology to previously recorded syllables. In many of the deafened birds, changes in song patterns were not evident until 6-8 weeks after surgery. These data indicate that continued auditory input is necessary to maintain the patterns of neural organization supporting learned song in zebra finches and raise questions concerning the neural sites and cellular mechanisms that mediate this feedback control.
Adult male zebra finches (Taeniopygia guttata), as closed-ended learners, normally crystallize their songs at 90 days of age, and the song remains fixed throughout life (Price, 1979). We show that injuring the tracheosyringeal nerve(s) (each of which innervates the ipsilateral half of the syrinx, the avian vocal organ) results in a short-term deficit in the syllables forming adult male song; this deficit disappears after ts nerve regeneration. However, when adult males were followed for a period of several weeks after unilateral tracheosyringeal nerve injury, long-term changes occurred in the temporal patterning of song. Syllables were deleted, remaining portions of the song were linked, and new syllables were added. Syllables with call-like morphology were less likely to be deleted from and more likely to be added to the song. Deletions were most often contiguous chunks of syllables. Changes in the temporal patterning of song occurred during specific periods following nerve injury, were completed within 100 days after nerve transection, and were not dependent upon regeneration of the ts nerve. The resulting newly formed song patterns were stable, remaining unchanged up to 1 year later. The ability of adult male zebra finches to make specific types of changes to crystallized song indicates that some form of vocal plasticity remains even after song learning is completed, though this plasticity may be restricted to a subset of song characteristics. The limitations on the types of changes that are possible may reflect how song is centrally organized.
Photoacoustic (PA) measurements provide, by the very nature of the PA effect, the possibility to obtain information on the optical and thermal properties of samples. In addition they can yield information on the enthalpy changes and characteristic times involved in photo-induced processes as the acoustic signal is proportional to the hear produced following the absorption of the modulated excitation. In the study of optical properties the relative insensitivity to scattered light of the PA signal makes such measurement an attractive way to measure biological samples in vivo, or, at least, without the need to isolate the absorbing compounds. The dependence of the PA signal on the thermal properties of the sample is particularly useful when heterogeneous samples are studied. As a photocalorimetric method the technique shows considerable promise in the study of photo-bioenergetics, especially photosynthesis. Only in special cases can analytical applications of the PA method compete with fluorescence measurements for detection, and with increasingly sophisticated optical transmission and reflectance techniques (for identification).. However, the PA method may find important uses in fundamental research and in applied areas such as biomedicine and agricultural biochemistry.
The mechanism underlying improvement after total sleep deprivation (TSD) was studied in 14 major depressed patients. The suggestions that (1) circadian processes and/or (2) dimensions of arousal may play a role in the response to TSD were investigated. Diurnal variation of depressed mood and of mood- and arousal-related vocal parameters was studied in relation to the effect of TSD on depressed mood and vocal parameters. During 3 baseline days, during TSD and 2 days after TSD vocal parameters and depressed mood were assessed 6 and 3 times daily respectively. The mean fundamental frequency (frequency of vocal fold vibration, F0) (presumably reflecting aspects of arousal) as well as the range of the F0 (proposed to reflect sadness) showed a clear circadian pattern with a peak at about 4.00 p.m. TSD affected the circadian organization of the mean F0 and advanced the peak of the curve. After one night of subsequent sleep this effect disappeared. In addition, improvement after TSD coincided with an increase of the mean F0. The diurnal variation of mood before TSD predicted the mood response to TSD, whereas diurnal variation of vocal parameters did not. Moreover, circadian changes in vocal parameters were not related to changes in depressed mood. These findings suggest that the diurnal variations in mood and vocal parameters are regulated by different mechanisms. Data support the presumption that circadian as well as arousal processes are involved in the mood response to TSD. Circadian changes in vocal parameters due to TSD are not likely to reflect changes in the biological clock.
The effect of corticotropin-releasing factor (CRF) on ultrasonic vocalizations (USVs) and other behaviors of isolated rat pups was examined at 5/6-, 9/10-, and 13/14-days. The hypothesis tested was that central CRF affects USV rate biphasically: as endogenous CRF increases from low basal levels it initiates USV production, but at higher levels CRF diminishes USV production. As predicted, the largest doses of CRF (0.1 and 1 microgram) and of its antagonist alpha-helical CRF9-41 (aH-CRF; 20 micrograms) administered intracerebroventricularly (ICV) reduced USV rate compared to saline treatment during a 2-min isolation at ambient temperature in pups of all ages. Other behaviors were either unaffected or increased by drug treatment. Effects were not attributable to sedation or to a change in core temperature. Peripheral administration of 1 microgram CRF or 20 micrograms aH-CRF had no effect. When isolation occurred in a heated chamber containing soiled bedding from the home cage to minimize baseline USV rate, ICV-CRF (0.001, 0.01, 0.1, or 1 microgram) did not enhance the rate. The quieting ability of aH-CRF is evidence that central endogenous CRF enhances the rate of ongoing USVs during brief isolation; the quieting ability of CRF suggests that this peptide may also be responsible for the reduction in USV rate that normally occurs during more protracted isolation. However, CRF alone is not sufficient to induce vocalizing in quiet pups.
The study of the acoustics of infants' vocalizations has important implications for the study of infant development and for clinical prediction. We suggest procedures that enhance the probability of discriminating among sub-glottal, periglottal, and supraglottal sites of pathology, With these procedures, then, it should become possible to contribute to diagnosis and therefore to treatment.
Ontogenic changes in ultrasound production by isolated rat pups were compared in male and female pups of litters of various sex compositions. In both sexes, the peak of emission of sound around 50 kHz was on days 4-5, while 40 kHz sound production peaked on days 6-7. By days 4-5 each pulse is an inverted V-shape with frequencies between 40 and 55 kHz. At the peak of sound production, pulses with a slight downsweep from 40-45 kHz were prominent, and in the preweaning period, pulses of a relatively stable frequency of 35-40 kHz were emitted. There was a general tendency for sound pulses of female pups to be of short duration compared with those of male pups. The ontogenic changes in the ultrasonic distress call are less variable throughout all female pups of litters consisting of 2, 4, 6 or 8 female pups in a litter of 8. In contrast to this, it was found that male pups emit ultrasound more vigorously than female pups from days 2-3 to days 12-13 when male and female pups coexisted in the same litter. The activity of sound production of male pups which had no female littermates was similar to that of female pups. These findings suggest that the interaction of some kind between male and female pups produces the sex differences in the ultrasonic distress calls as early as several days after birth in the rat.
The metrological and computational problems of detecting very weak variations in the frequencies of the fundamental tone are discussed from a signal processing point of view. An appropriate computer method of high-resolution analysis of the fundamental frequency is proposed. When applying high-resolution fundamental frequency analysis to cry signals, a jitter was found to exist in the fundamental frequency curve of both healthy babies and those suffering from cerebral disorders. A method is given to separate the jitter from the fundamental frequency curve. The separated jitter curve depends on the degree of slope of the fundamental frequency curve and shows differences between healthy and ill babies. For an objective evaluation of the jitter abnormities, an integral parameter--the so-called cry-jitter index--is proposed.
The phonetogram represents an area limited by piano and forte contours of the sound pressure levels along the vocal range. Phonetograms are used in the diagnosis of voice status. Apart from reference phonetograms and the extraction of single parameters, phonetograms have not been evaluated quantitatively in medical practice. The present computer program divided the phonetogram into subareas which were approximated by simple patterns (ellipses). The ellipse parameters were used to evaluate voice efficiency, to recognize voice categories, and to derive diagnostic comments.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Secondary sound emission, partly in the audible frequency range, from shock wave disintegration of kidney stones has been recorded during the treatment of two patients. A skilled operator can determine by listening if the stone is hit by the shock-wave or not. Spectral analysis of these recordings show differences between the sounds which can be used to evaluate the fragmenting effect on the stone. Results are presented of a preliminary discriminating method based on parameters in an autoregressive signal model.
Fourteen infants who were undergoing routine immunization were studied from a multidimensional perspective. The measures used were heart rate, crying, body movement/posturing, and voice spectrographs. There was wide variability between infants on the measures, especially on the cry spectrographs, although facial expression was consistent across infants. The pattern that did emerge was characterized by an initial response: a drop in heart rate, a long, high pitched cry followed by a period of apnea, rigidity of the torso and limbs, and a facial expression of pain. This was followed by a sharp increase in heart rate, lower pitched, but dysphonated cries, less body rigidity, but still facial expression was of pain. Finally, in the second half of the minute's response, heart rate remained elevated, cries were lower pitched, more rhythmic, with a rising-falling pattern, and were mostly phonated, and body posturing returned to normal. Those faces that could be viewed also were returning to the at rest configuration. It was suggested that facial expression may be the most consistent across-infant indicator of pain at this point in time.
A cotton tip applicator was utilized to stimulate far IR scatter (emission) from human breath. The reticulated cotton tip was vibrated at 200 Hz, the acoustic frequency that matches the average vibration frequency of common species of mosquitoes. Mosquitoes have open resonator dielectric sensillae (spines) on their antenna that match the 643 cm-1 (15.5) Cabannes line in the 667 cm-1 region of CO2 rotation line, acoustic Stokes Brillouin and Stokes Raman lines are noted. Implications of such maserlike (coherent or partial coherent) scatter lines to insect control and disease diagnostics are discussed.
Sound spectrographic cry analysis was performed on 302 cries of 48 preterm infants born at 30-37 gestational weeks. The cries were recorded during the first week of life and thereafter weekly until the infants were discharged. The control series comprised 54 cries from 27 fullterm healthy infants. The results showed that the cries of the smallest prematures compared with the controls were shorter, more high-pitched, and included bi-phonation and glide more often. The cry characteristics changed with increasing conceptual age and the older the child the more the cry pattern resembled that of the fullterm. The cries of the preterm infants when they had reached 38 conceptual weeks were similar to those of newly born fullterm infants. The results indicate that the gestational age should be taken into consideration in cry analysis.
Representation of simple stationary sounds can be given either in the temporal form by display of the waveform as function of time or in the spectral form by intensity and phase as function of frequency. For complex nonstationary sounds, e.g. animal vocalisations and human speech, a combined spectro-temporal representation is more directly associated with auditory perception. The well-known sonogram or dynamic power spectrum has a fixed spectro-temporal resolution and neglects phase relations of different spectral and temporal sound components. In this paper the complex spectro-temporal intensity density CoSTID) is presented as a coherent spectro-temporal image of a sound, based on the analytic signal representation. The CoSTID allows an arbitrary form of the spectro-temporal resolution and preserves phase relations of different sound components. Since the CoSTID is a complex function of two variables, it leads naturally to the use of colour images for the spectro-temporal representation of sound: the phonochrome. The phonochromes are shown for different technical and natural sounds. Applications of this technique for study of phonation and audition and for biomedical signal processing are indicated.