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Biomedical subjects

J Sundberg

Publications and source records attributed to J Sundberg.

At least 55 records · Page 3Linked to original sources
PubMed1994

Relations between voice range profiles and physiological and perceptual voice characteristics in ten-year-old children.

Pitch and intensity range of 60 children were recorded and plotted in voice range profiles (VRPs). Different aspects were investigated: minimum phonation threshold, pitch range, and maximum dynamic range. Vocal fold status was determined via laryngoscopic examination. Ten percent of the children had vocal nodules, 23% glottal chinks. Seven voice experts listened to the voices recorded on two separate occasions and rated their properties along 16 parameters including hoarseness. Fourteen percent were rated as hoarse on both recordings and were thus classified as being chronically hoarse. Departures from normal in VRP characteristics were found for children suffering from chronic hoarseness, nodules, and glottal chinks. Children in general seem to have somewhat compressed VRP contours compared with adults, reflecting restricted dynamic vocal capabilities; however, children with mutational voices exhibited an approximation to adult upper VRP contours.

Auditory Perception↗
PubMed1994

Perceptual aspects of singing.

The relations between acoustic and perceived characteristics of vowel sounds are demonstrated with respect to timbre, loudness, pitch, and expressive time patterns. The conditions for perceiving an ensemble of sine tones as one tone or several tones are reviewed. There are two aspects of timbre of voice sounds: vowel quality and voice quality. Although vowel quality depends mainly on the frequencies of the lowest two formants. In particular, the center frequency of the so-called singer's formant seems perceptually relevant. Vocal loudness, generally assumed to correspond closely to the sound pressure level, depends rather on the amplitude balance between the lower and the higher spectrum partials. The perceived pitch corresponds to the fundamental frequency, or for vibrato tones, the mean of this frequency. In rapid passages, such as coloratura singing, special patterns are used. Pitch and duration differences are categorically perceived in music. This means that small variations in tuning or duration do not affect the musical interval and the note value perceived. Categorical perception is used extensively in music performance for the purpose of musical expression because without violating the score, the singer may sharpen or flatten and lengthen or shorten the tones, thereby creating musical expression.

Auditory Perception↗
PubMed1993

Winter dysentery diagnosed by farmers in dairy herds in central Sweden: incidence, clinical signs and protective immunity.

The occurrence of winter dysentery, diagnosed by farmers and defined as an outbreak of diarrhoea among at least 30 per cent of adult cattle in a herd, was monitored in 256 dairy herds in an area of central Sweden. The cumulative incidence of winter dysentery between April 1988 and March 1989 was 28.5 per cent. A typical outbreak lasted for one to two weeks and 74 per cent of the outbreaks occurred between November and January. A decrease in milk yield was reported in 90 per cent of the affected herds and the cows showed respiratory signs in 57 per cent of them. There was a significant (P < 0.05) association between the occurrence of fever and coughing. In 31 per cent of the outbreaks the farmer also noticed diarrhoea among the calves. One-third of the affected herds had experienced an outbreak within the previous four years and 18 per cent had at least one further outbreak during the following two years. There was a significantly (P < 0.05) lower disease score in herds that had had an outbreak within the previous four years than in herds which had had a less recent or no previous outbreak, indicating the development of temporary immunity to the causative agent.

Animals↗
PubMed1993

Phonatory control in male singing: a study of the effects of subglottal pressure, fundamental frequency, and mode of phonation on the voice source.

This article describes experiments carried out in order to gain a deeper understanding of the mechanisms underlying variation of vocal loudness in singers. Ten singers, two of whom are famous professional opera tenor soloists, phonated at different pitches and different loudnesses. Their voice source characteristics were analyzed by inverse filtering the oral airflow signal. It was found that the main physiological variable underlying loudness variation is subglottal pressure (Ps). The voice source property determining most of the loudness variation is the amplitude of the negative peak of the differentiated flow signal, as predicted by previous research. Increases in this amplitude are achieved by (a) increasing the pulse amplitude of the flow waveform; (b) moving the moment of vocal fold contact earlier in time, closer to the center of the pulse; and (c) skewing the pulses. The last mentioned alternative seems dependent on both Ps and the ratio between the fundamental frequency and the first formant. On the average, the singers doubled Ps when they increased fundamental frequency by one octave, and a doubling of the excess Ps over threshold caused the sound pressure level (SPL) to increase by 8-9 dB for neutral phonation, less if mode of phonation was changed to pressed. A shift of mode of phonation from flow over neutral to pressed was associated with a reduction of the peak glottal permittance i.e., the ratio between peak transglottal airflow to Ps. Flow phonation had the most favorable relationship between Ps and SPL.

Air Pressure↗
PubMed1993

Comparisons of pharynx, source, formant, and pressure characteristics in operatic and musical theatre singing.

Belting, a vocal technique typically cultivated in musical theatre singing, differs timbrally from operatic singing in many interesting respects. The underlying phonatory differences have not been previously investigated in detail. Yet, belting is frequently associated with disturbances of voice function. Articulatory and phonatory characteristics are investigated in a female subject who is a professional singer (co-author JL) trained in both the operatic and belting styles and in an intermediate vocal technique ("mixed"). This article presents data obtained from this subject by video-fiberoptic observation of the pharynx, inverse filtering of airflow, and measurement of subglottal pressure. The results reveal that belting was characterized by very high subglottal pressures and sound levels, and apparently also by a comparatively high degree of glottal adduction. Comparisons with other investigations of related aspects of belting and operatic singing support the assumption that the data obtained from our subject are representative for these vocal techniques.

Female↗
PubMed1993

Short-term variation of subglottal pressure for expressive purposes in singing and stage speech: a preliminary investigation.

According to previous investigations, subglottal pressure in singing is adapted not only to loudness but also to fundamental frequency. Here the significance of musical expression to subglottal pressure is analyzed in terms of alternations between stressed and unstressed bar positions. Esophageal pressure was recorded together with the audio signal in a male and a female professional singer using a paranasally introduced pressure transducer while the subjects performed vocal exercises. Also, the subjects gave examples of actors' speech by reading poetry aloud. The results show that subglottal pressure can be used for stressing the first beat in bars and also for increasing the sound level in voiced consonants in actor's speech.

Air Pressure↗
PubMed1992

Lead poisoning in cattle--transfer of lead to milk.

The transfer of lead to milk in cattle in relation to blood lead levels and the uptake of lead in edible tissues was studied for an accidental exposure over 1 or 2 days to lead in excessive amounts from the licking of burnt storage batteries. The degree of exposure was monitored by determination of blood lead levels. Milk and blood samples were taken from eight cows, without acute symptoms of lead poisoning, during a period of 18 weeks. Two weeks after the accidental exposure, lead levels (mean +/- SD) in milk were 0.08 +/- 0.04 mg kg-1 and in blood 0.36 +/- 0.04 mg kg-1 in six of the cows. The relationship between lead concentration in blood and those in milk was found to be exponential and could be expressed by the equation: log y = 3.19x - 2.36 (r = 0.85, p less than 0.001), where y and x are the lead concentrations in milk and blood, respectively. The lead level in milk was relatively constant up to a blood lead level of 0.2-0.3 mg kg-1, and increased sharply at higher blood levels. The biological half-life of lead in blood was shown to be approximately 9 weeks. In eight acutely sick cows, which were emergency slaughtered, the range of lead levels in edible muscle tissue was 0.23-0.50 mg kg-1 wet weight. Very high concentrations were found in the kidneys, with a range of 70-330 mg kg-1, and in the livers, with a range of 10-55 mg kg-1. Four of the cows were pregnant, in the first or second month of gestation, during the episode of exposure. The lead exposure was not found to disturb the gestation or development of the fetuses.

Animals↗
PubMed1992

Formant frequency estimates for abruptly changing area functions: a comparison between calculations and measurements.

Vocal tract area functions may contain quite abrupt changes in cross-sectional area. In formant frequency calculations for such area functions, an inner length correction (ILC) should be applied. The relevance of this correction was investigated by comparing acoustic measurements obtained from a physical model of the vocal tract with data gathered by means of computer simulations. Calculating formant frequencies without applying internal length corrections caused substantial errors, particularly for area functions representing apical stops just anterior to occlusion. Decentering and axial symmetry in the arrangement of the area elements of the physical model were briefly studied and found to have effects on the formant frequency values.

Humans↗
PubMed1992

Vocal intensity in speakers and singers.

Vocal intensity is studied as a function of fundamental frequency and lung pressure. A combination of analytical and empirical models is used to predict sound pressure levels from glottal waveforms of five professional tenors and twenty five normal control subjects. The glottal waveforms were obtained by inverse filtering the mouth flow. Empirical models describe features of the glottal flow waveform (peak flow, peak flow derivative, open quotient, and speed quotient) in terms of lung pressure and phonation threshold pressure, a key variable that incorporates the Fo dependence of many of the features of the glottal flow. The analytical model describes the contributions to sound pressure levels SPL by the vocal tract. Results show that SPL increases with Fo at a rate of 8-9 dB/octave provided that lung pressure is raised proportional to phonation threshold pressure. The SPL also increases at a rate of 8-9 dB per doubling of excess pressure over threshold, a new quantity that assumes considerable importance in vocal intensity calculations. For the same excess pressure over threshold, the professional tenors produced 10-12 dB greater intensity than the male nonsingers, primarily because their peak airflow was much higher for the same pressure. A simple set of rules is devised for predicting SPL from source waveforms.

Glottis↗
PubMed1991

Methylmercury induced alterations in the nerve growth factor level in the developing brain.

Pre- and early postnatal stages in the development of the central nervous system (CNS) are very sensitive to the toxic effects of methylmercury. The influence of methylmercury on the level of nerve growth factor (NGF) during the development of CNS was studied. Sprague-Dawley rats were exposed indirectly throughout the fetal and suckling periods until weaning on postnatal day 25 (P 25) via their dams given methylmercury in the diet (3.9 mg/kg diet). In addition, after weaning offsprings were exposed directly to methylmercury via the diet until postnatal day 50 (P 50). The level of NGF was analyzed in cortical areas and in the septum with a sensitive enzyme immunoassay. The pups exposed to MeHg exhibited a 50% elevation in the level of NGF in the hippocampus on P 25 and P 50 compared to control animals. Concomitantly, the level of NGF decreased by 30% in the septum on P 25 and P 50, suggesting that the retrograde transport of NGF from hippocampus to septum could be affected by the exposure of methylmercury. The exact mechanism by which the low level of mercury is affecting the NGF concentration in the developing brain is yet unknown. The increase of NGF in the hippocampus and the decrease of NGF measured in the septum could reflect altered conditions for neurotrophic support in these areas of the brain as a result of the exposure to heavy metal. Thus, this finding might indicate a connection between exposure of heavy metals and neurodegeneration, such as that found in the basal forebrain in Alzheimer's disease.

Animals↗
PubMed1991

Persistent cutaneous ulcers associated with feline herpesvirus type 1 infection in a cheetah.

Persistent cutaneous ulcers developed in a female cheetah cub after an episode of rhinotracheitis. When they were 3 weeks old, the cub and a male littermate developed mucopurulent oculonasal discharge consistent with feline herpesvirus type 1 infection (feline viral rhinotracheitis). The male cub was weaned and its lesions resolved. The female cub remained with the dam until the cub was 3 months old, at which time plaque-like lesions developed on the eye margins and muzzle. These plaques regressed over the next month and were replaced with cutaneous ulcers ranging from 1 to 10 mm in diameter. Feline herpesvirus type 1 was isolated from biopsy specimens collected from the ulcers. Cutaneous ulcers are uncommon manifestations of feline herpesvirus infections and have not been reported in other exotic fields. A proposed susceptibility to viral infections related to low genetic diversity has been proposed in cheetahs, and may be involved in the pathogenesis of persistent herpetic ulcers.

Acinonyx↗
PubMed1991

Milk transfer of inorganic mercury to suckling rats. Interaction with selenite.

The transport of mercury into rat milk, and uptake in the suckling offspring was studied after peroral administration of inorganic mercury to lactating control rats, and to rats fed selenite in the diet. On day 8, 9, 10, or 11 of lactation, dams were administered a single oral dose of 0.1, 0.4, 0.7, 1.3, or 5.8 mg Hg/kg bw labeled with 203mercuric acetate. There was a linear relationship between mercury concentrations in dam's plasma and milk. The level of mercury in milk was approximately 25% of the level in plasma. After 3 d, milk levels were reduced to half the levels at 24 h. In the suckling offspring, exposed to mercury via milk during 3 d, the mercury level in blood was approximately 1% of the level in maternal blood. Mercury concentration in milk was linearly correlated to the levels in kidney, liver, and brain in the suckling offspring after 3 d exposure to mercury via milk. Selenite treatment of rats, 1.3 micrograms Se/g diet for 5 mo, resulted in increased transport of mercury to milk, probably because of increased plasma levels of mercury. However, selenite treatment of the dams did not cause any increased tissue levels of mercury in the suckling offspring.

Animals↗
PubMed1991

Methyl mercury exposure via placenta and milk impairs natural killer (NK) cell function in newborn rats.

The effect of methyl mercury (MeHg) exposure (3.9 micrograms/g diet) on the development of immune function was studied in the newborn Sprague-Dawley rat after MeHg exposure via placenta and/or milk. No consistent alterations were observed between control and treated offspring (at the age of 15 days) on the following parameters: body weights, lymphoid organ weights or cell number, and the lymphoproliferative response to B-cell mitogen. The lymphoproliferative response to T-cell mitogen was increased in thymocytes (by 30-48%), but decreased in splenocytes (by 30-32%). This decreased activity was only observed in the groups exposed during lactation. White blood cell counts (WBC) were increased in all groups. Natural killer (NK) cell activity was reduced (by 42%, P less than 0.01) in the group that was exposed both via placenta and milk. These results indicate that placental and lactational transfer of MeHg does adversely affect the developing immune system of the rat.

Animals↗
PubMed1991

Effects of long-term treatment with methyl mercury on the developing rat brain.

Sprague-Dawley rats were exposed to low doses of methyl mercury (3.9 mg mercury/kg diet), via their dams during gestation and lactation and directly via their diet until sacrifice at 50 days postpartum, in order to study possible detrimental effects on CNS development. The methyl mercury exposure of the rats resulted in a brain concentration of 1.45 +/- 0.06 mg mercury/kg wet weight (mean +/- SEM). No general toxic effects were observed; body weight was not affected, brain weight was only slightly increased. No discernible general morphological alterations were seen in the brain as evaluated using cresyl violet histology. Furthermore, no effects on GFA-positive astrocytes in brain sections were observed and computerized morphometry of smeared astrocytes from frontal cortex, hippocampus, and cerebellum did not reveal any effects of the methyl mercury treatment. The noradrenaline (NA) and dopamine (DA) systems were also studied. In cerebellum the NA levels were increased (117% of controls, P = 0.008), whereas in other regions analyzed NA and DA levels were unchanged. Thus, long-term low-dosage exposure of methyl mercury in rats during development does not appear to exert any major effects on the morphological maturation of neurons and astrocytes. However, the results indicate that effects may occur in specific transmitter-identified systems, such as the NA input to cerebellum. The results therefore underline the need for detailed biochemical analyses to study the effects of long-term low-dosage exposure to neurotoxic compounds.

Animals↗
PubMed1991

Transfer of 137cesium via rat milk: reduction with ammonium ferric hexacyanoferrate.

Dose-dependent transfer of 137cesium (137Cs) into milk and uptake in suckling rats after a three-day nursing period was studied. On lactation day 9, the dams were administered a single oral dose of cesium, labeled with 137cesium chloride, in six doses from 0.4 to 19.7 micrograms Cs/kg. In addition, one group of rats was given ammonium-ferric(III)-hexacyanoferrate(II) (AFCF). There was a linear dose-dependent relationship between Cs levels in plasma and milk, as well as in whole blood and milk. The Cs milk/plasma ratios were 7 at 24 hr and 6 at 72 hr after Cs administration. Cesium concentration in milk was linearly correlated with tissue levels in suckling offspring at 72 hr. Concentration ratios of cesium in tissues between pups and their lactating dams ranged from 0.5 to 1.2. Repeated treatment with AFCF (50 mg) given orally at 24, 30, 48 and 54 hr after a single administration of 137Cs, resulted in significantly decreased Cs levels in dam's kidney, liver, lung, erythrocytes and blood at 72 hr. In addition, Cs level in milk was decreased by 40% in rats treated with AFCF. However, no effects of AFCF on Cs levels in tissues of suckling pups were observed.

Animals↗
PubMed1991

Variability of phonetograms.

Various sources of phonetogram variation were investigated, i.e. graphs showing voice sound pressure level (SPL) for a speaker's loudest and softest phonation at different fundamental frequencies. The short-term SPL variation within a vocalization was analyzed for 10 female and 10 male normal speakers and for 10 female patients with nonorganic dysphonia, i.e. patients with insufficient voices and no indication of pathology according to microlaryngostroboscopy. This variability was about 5 dB in soft phonation and less in loud phonation. The agreement between 2 investigators independently determining SPL for identical vocalizations by means of a sound-level meter was also studied and found to be quite good. The long-term variation was analyzed in 1 male and 1 female normal subject in 15 phonetogram recordings made on different days; the standard deviation averaged across fundamental frequency and subjects was found to be approximately 3 dB. The implications of these findings for a clinical use of phonetograms are discussed.

Adult↗
PubMed1990

Acoustic estimations of the front cavity in apical stops.

Sweep-tone measurements of front-cavity resonances in apical stops are reported. Volumes inferred from resonance frequency data are presented as a function of place of articulation. The results indicate that, for post-dental points of contact, a cavity located under the tongue tip is formed. It is shown that this sublingual cavity plays a very important role in shaping the spectral structure of apical stops.

Humans↗