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PubMed1982

The detection and quantification of sleep apnea by tracheal sound recordings.

Tracheal sound recordings and O2 saturation were compared with conventional recordings of respiratory events (thermistors, strain gauges, and O2 saturation) in 14 patients referred for assessment of sleep apnea syndrome. There was no significant difference in the number of respiratory events associated with desaturation recorded during the sleep by the two methods. Tracheal sound recordings were more useful in analyzing the cause of the respiratory event. Hypopnea without desaturation was seen more often with tracheal sound recordings than with the conventional methods. The durations of apneic and hypopneic events were significantly longer when recorded by thermistors and strain gauges than by breath sounds.

Adult↗

PubMed2005

Relationship between habitual occlusal position and flat bite plane induced occlusal position in volunteers with and without temporomandibular joint sounds.

The aim of this study was to assess whether temporomandibular joint (TMJ) sounds are associated with the difference between the habitual occlusal position (HOP) and the bite plane induced occlusal position (BPOP). Fifteen dental technician school students who had complete natural dentition, normal occlusion and who exhibited TMJ sounds were compared with fifteen healthy control subjects. HOP was recorded by voluntary jaw closing while in an upright position, and BPOP was recorded after wearing an anterior bite plane for a short period of time. Three interocclusal records were obtained in both positions with a vinyl polysiloxane material, and the recorded maxillomandibular relations were analyzed three-dimensionally and compared. Subjects with TMJ sounds had statistically larger differences between HOP and BPOP than controls (p<.05). Within this study population, an association was found between TMJ sounds and the difference between HOP and BPOP.

Adolescent↗

PubMed2005

Simultaneous measurement of metabolic and acoustic power and the efficiency of sound production in two mole cricket species (Orthoptera: Gryllotalpidae).

We here report the first simultaneous measurement of metabolic cost of calling, acoustic power and efficiency of sound production in animals--the mole crickets Scapteriscus borellii and S. vicinus (Gryllotalpidae). We measured O(2) consumption, CO(2) production and acoustic power as the crickets called from their burrows in an open room. We utilized their calling burrow as the functional equivalent of a mask. Both species had a respiratory quotient near 0.85, indicative of metabolism based on a mix of carbohydrates and fats. The metabolic rate was significantly higher in S. borellii (11.6 mW g(-1)) than in S. vicinus (9.0 mW g(-1)) and averaged about eight- to fivefold greater, respectively, than resting metabolism. In some individuals, metabolic rate decreased by 20% during calling bouts. Costs of refurbishing calling burrows in S. borellii were less than calling costs, due to the behavior's short duration (ca. 15 min) and its relatively low average metabolic rate (4 mW). Acoustic power was on average sevenfold greater in S. borellii (21.2 vs 2.9 microW) and was more variable within individuals and across species than the metabolic rate. The efficiency of sound production was significantly higher in S. borellii (0.23 vs 0.03%). These values are below published estimates for other insects even though these mole crickets construct acoustic burrows that have the potential to increase efficiency. The cricket/burrow system in both species have an apparent Q(ln decrement) of about 6, indicative of significant internal damping caused by the airspaces in the sand that forms the burrow's walls. Damping is therefore an important cause of the low sound production efficiency. In field conditions where burrow walls are saturated with water and there is less internal damping, calls are louder and sound production efficiency is likely higher. File tooth depths and file tooth-to-tooth distances correlated with interspecific differences in metabolism and acoustic power much better than with wing stroke rates and plectrum-to-file tooth strike rates. To further investigate these correlations, we constructed two models of energy input to the tegminal oscillator. A model based on transfer of kinetic energy based on differences in tegminal velocity and file tooth spacing showed the most promise. Related calculations suggest that if there are no elastic savings, the power costs to accelerate and decelerate the tegmina are greater than the predicted power input to the tegminal oscillator, and that they are similar in the two species even though S. vicinus has a nearly threefold higher wing stroke rate.

Acoustics↗

PubMed1993

What ears do for bats: a comparative study of pinna sound pressure transformation in chiroptera.

Using a moveable loudspeaker and an implanted microphone, we studied the sound pressure transformation of the external ears of 47 species of bats from 13 families. We compared pinna gain, directionality of hearing and interaural intensity differences (IID) in echolocating and non-echolocating bats, in species using different echolocation strategies and in species that depend upon prey-generated sounds to locate their targets. In the Pteropodidae, two echolocating species had slightly higher directionality than a non-echolocating species. The ears of phyllostomid and vespertilionid species showed moderate directionality. In the Mormoopidae, the ear directionality of Pteronotus parnellii clearly matched the dominant spectral component of its echolocation calls, unlike the situation in three other species. Species in the Emballonuridae, Molossidae, Rhinopomatidae and two vespertilionids that use narrow-band search-phase echolocation calls showed increasingly sharp tuning of the pinna to the main frequency of their signals. Similar tuning was most evident in Hipposideridae and Rhinolophidae, species specialized for flutter detection via Doppler-shifted echoes of high-duty-cycle narrow-band signals. The large pinnae of bats that use prey-generated sounds to find their targets supply high sound pressure gain at lower frequencies. Increasing domination of a narrow spectral band in echolocation is reflected in the passive acoustic properties of the external ears (sharper directionality). The importance of IIDs for lateralization and horizontal localization is discussed by comparing the behavioural directional performance of bats with their bioacoustical features.

Animals↗

PubMed1999

Mosquito hearing: sound-induced antennal vibrations in male and female Aedes aegypti.

Male mosquitoes are attracted by the flight sounds of conspecific females. In males only, the antennal flagellum bears a large number of long hairs and is therefore said to be plumose. As early as 1855, it was proposed that this remarkable antennal anatomy served as a sound-receiving structure. In the present study, the sound-induced vibrations of the antennal flagellum in male and female Aedes aegypti were compared, and the functional significance of the flagellar hairs for audition was examined. In both males and females, the antennae are resonantly tuned mechanical systems that move as simple forced damped harmonic oscillators when acoustically stimulated. The best frequency of the female antenna is around 230 Hz; that of the male is around 380 Hz, which corresponds approximately to the fundamental frequency of female flight sounds. The antennal hairs of males are resonantly tuned to frequencies between approximately 2600 and 3100 Hz and are therefore stiffly coupled to, and move together with, the flagellar shaft when stimulated at biologically relevant frequencies around 380 Hz. Because of this stiff coupling, forces acting on the hairs can be transmitted to the shaft and thus to the auditory sensory organ at the base of the flagellum, a process that is proposed to improve acoustic sensitivity. Indeed, the mechanical sensitivity of the male antenna not only exceeds the sensitivity of the female antenna but also those of all other arthropod movement receivers studied so far.

Acoustic Stimulation↗

PubMed2000

Effects of fish size and temperature on weakfish disturbance calls: implications for the mechanism of sound generation.

To categorize variation in disturbance calls of the weakfish Cynoscion regalis and to understand their generation, we recorded sounds produced by different-sized fish, and by similar-sized fish at different temperatures, as well as muscle electromyograms. Single, simultaneous twitches of the bilateral sonic muscles produce a single sound pulse consisting of a two- to three-cycle acoustic waveform. Typical disturbance calls at 18 degrees C consist of trains of 2-15 pulses with a sound pressure level (SPL) of 74 dB re 20 microPa at 10 cm, a peak frequency of 540 Hz, a repetition rate of 20 Hz and a pulse duration of 3.5 ms. The pulse duration suggests an incredibly short twitch time. Sound pressure level (SPL) and pulse duration increase and dominant frequency decreases in larger fish, whereas SPL, repetition rate and dominant frequency increase and pulse duration decreases with increasing temperature. The dominant frequency is inversely related to pulse duration and appears to be determined by the duration of muscle contraction. We suggest that the lower dominant frequency of larger fish is caused by a longer pulse (=longer muscle twitch) and not by the lower resonant frequency of a larger swimbladder.

Acoustic Stimulation↗

PubMed2001

Physical factors affecting the cost and efficiency of sound production in the treefrog Hyla versicolor.

The metabolic cost, energy output and efficiency (i.e. the ratio of energy output to metabolic cost) of sound production were compared among male grey treefrogs (Hyla versicolor) as a function of body size and temperature. The effects of call length (in notes per call) and dominant frequency (in kHz) were also considered. Cost, determined from the amount of oxygen consumed, averaged 12.1 mJ per note and was dependent only upon body mass. Acoustic energy per note, determined from oscillograms of recorded calls, averaged 0.34 mJ and was dependent only upon temperature. Conventional theory suggests that the efficiency of sound production should be a function of the ratio of the linear size of the radiating structures to the wavelength of the sound generated (i.e. efficiency is assumed to be a function of the product of mass(0.33) and frequency), but efficiency in H. versicolor was found to be a function of the product of temperature(2.1) and mass(-1.08). Adjusting for temperature and body mass, the efficiency of sound production in H. versicolor (average 2.4 %) is greater than the efficiency of other frog species for which data are available. Temperature may affect acoustic energy output because trunk muscle contraction speed increases with temperature, which increases the velocity of airflow across the vocal cords.

Animals↗

PubMed1998

An early systolic sound associated with midventricular obstruction in a patient with hypertrophic cardiomyopathy.

A 57-year-old woman was admitted for examination because of chest discomfort. Transthoracic echocardiography was performed and she was diagnosed as having hypertrophic cardiomyopathy. An echocardiogram also revealed that she had midventricular obstruction with a pressure gradient of 125 mmHg determined by Doppler echocardiography. A phonocardiogram showed an early systolic sound and the beginning of the sound coincided with the time of septal-posterior wall contact. In addition, the timing also corresponded to the sudden obstruction of blood flow in the region of the midventricular narrowing. Furthermore, this sound markedly decreased with the reduction in pressure gradient caused by cibenzoline treatment. Thus, it was concluded that the early systolic sound was associated with midventricular obstruction and produced by a rapid deceleration of the interventricular flow caused by midventricular obstruction.

Anti-Arrhythmia Agents↗

PubMed2003

Temporomandibular internal derangement: correlation of MRI findings with clinical symptoms of pain and joint sounds in patients with bruxing behaviour.

OBJECTIVES: The aim of this study was to correlate magnetic resonance imaging (MRI) findings of effusion, disc displacement, condylar bony changes and disc form with clinical findings of pain and sounds in patients with bruxing and non-bruxing behaviour. METHODS: Disc displacement was confirmed by MRI in 102 joints from 64 patients (total of 128 joints) with bruxing behaviour who were referred for clinically diagnosed internal derangements of the temporomandibular joint (TMJ). Sixty joints with internal derangement from 30 patients without bruxing behaviour served as a control group. The clinical inclusion criteria were pain in the pre-auricular area and muscles of mastication, limitation or deviation in mandibular range of motion, and TMJ sounds. Signs of bruxism were diagnosed clinically and were obtained from the patient's history given on their first visit. Pain was evaluated using a visual analogue scale. RESULTS: Of the 102 joints in the study group with disc displacement, 53 (52%) showed disc displacement with reduction and 49 (48%) showed disc displacement without reduction. In the control group, 16 joints were classified as normal. Of the remaining 44 joints, 27 (61%) had disc displacement with reduction and 17 (39%) had unilateral disc displacement without reduction. Condylar bony changes were seen in 55% of the reducing joints in the study group and in 38% of the reducing joints in the control group, compared with 86% of the non-reducing joints in the study group and 24% of the non-reducing joints in the control group. There was a strong correlation between age and degenerative change in the study group. In the reducing joints, there was a significant difference in the prevalence of condylar bony changes between the study and control groups (P<0.01). In non-reducing joints, 30% of painful joints in the study group and 59% of those in the control group showed a strong signal in the joint space on T(2) weighted imaging. Statistically significant differences between the study and control groups were also found for disc form and the prevalence of effusion and disc displacement. Joint sounds were important in unilaterally affected joints in the study group. A statistically significant correlation was found between joint sounds and reducing joints (P<0.05). CONCLUSION: It was demonstrated that a higher prevalence of condylar bony changes occurred in reducing joints in patients with bruxing behaviour.

Adolescent↗

PubMed1978

Abnormal pulmonic sound during acute massive pulmonary embolism.

The findings in two patients with angiographically proven massive pulmonary embolism and with clinical and phonocardiographic evidence of abnormal respiratory movement of the pulmonic sound are reported. One patient with complete right bundle-branch block and another with normal conduction had a wide and fixed split second sound with a loud pulmonic component. Both patients had a moderate degree of pulmonary hypertension. Approximately two weeks after administration of heparin, the pulmonic sound moved normally during respiration in both patients. Thromboembolic pulmonary hypertension regressed in one patient and remained unchanged in the other. Changes in impedance through the large pulmonary arteries are are postulated to be responsible for the abnormal movement of the pulmonic valve during both phases of respiration. Wide expiratory splitting of the second sound should be an important clue in the diag nosis of acute massive pulmonary embolism, and the reappearance of a normal inspiratory splitting could be used at the beside to assess indirectly the rate of resolution of the blood clots.

Acute Disease↗

PubMed2002

Improvement of ultrasound compound imaging by speed-of-sound estimation.

It is well known that the superposition of ultrasound images of the same object acquired from different directions reduces speckle and improves image quality. Philips/ATL were the first to overlay up to nine images using a phased linear array with different steering angles for real-time compound imaging. However, image quality suffers from speed of sound deviations from the velocity of 1540 m/s assumed by ultrasonic scanners. It has been shown that this is relevant in anatomical imaging and image quality can be improved significantly by estimating the speed of sound [1] and correcting for deviations. In this paper, average sound speed estimation based on a compound image quality criterion is discussed. Additionally, the criteria presented are evaluated for a simple case of local speed of sound estimation.

Artifacts↗

PubMed2001

The pathway for the transmission of external sounds into the fetal inner ear.

After at least 20 weeks gestation, the human fetus in utero is able to hear and respond to external and internal (maternal) sounds. The external sounds are attenuated by maternal tissues and fluids - higher frequencies by about 20 dB, and lower frequencies are only slightly reduced. The sounds in the amniotic fluid, which completely envelops the fetus, then reach the fetal inner ear by bone conduction. The sound pressure in the amniotic fluid induces skull vibrations which are transmitted directly into the contents of the cranial cavity (brain and CSF) and from there, presumably by fluid channels connecting them, into the cochlear fluids. A further stage of conductive attenuation is probably involved in this transmission. Since the fetus in utero receives oxygen by placental diffusion (less efficient than pulmonary diffusion), the fetal inner ear is hypoxic compared to that following birth (pulmonary oxygen diffusion). This leads to a reduction in the magnitude of the endocochlear potential, to a depression of cochlear transduction and amplification, and thus to an additional sensorineural component of threshold elevation in the fetus. Upon birth, these conductive and sensorineural attenuations are removed.

Amniotic Fluid↗

PubMed2006

Navigation performance with a virtual auditory display: effects of beacon sound, capture radius, and practice.

OBJECTIVE: We examined whether spatialized nonspeech beacons could guide navigation and how sound timbre, waypoint capture radius, and practice affect performance. BACKGROUND: Auditory displays may assist mobility and wayfinding for those with temporary or permanent visual impairment, but they remain understudied. Previous systems have used speech-based interfaces. METHOD: Participants (108 undergraduates) navigated three maps, guided by one of three beacons (pink noise, sonar ping, or 1000-Hz pure tone) spatialized by a virtual reality engine. Dependent measures were efficiency of time and path length. RESULTS: Overall navigation was very successful, with significant effects of practice and capture radius, and interactions with beacon sound. Overshooting and subsequent hunting for waypoints was exacerbated for small radius conditions. A human-scale capture radius (1.5 m) and sonar-like beacon yielded the optimal combination for safety and efficiency. CONCLUSION: The selection of beacon sound and capture radius depend on the specific application, including whether speed of travel or adherence to path are of primary concern. Extended use affects sound preferences and quickly leads to improvements in both speed and accuracy. APPLICATION: These findings should lead to improved wayfinding systems for the visually impaired as well as for first responders (e.g., firefighters) and soldiers.

Adolescent↗

PubMed2005

Relearning sound localization with a new ear.

Human sound localization results primarily from the processing of binaural differences in sound level and arrival time for locations in the horizontal plane (azimuth) and of spectral shape cues generated by the head and pinnae for positions in the vertical plane (elevation). The latter mechanism incorporates two processing stages: a spectral-to-spatial mapping stage and a binaural weighting stage that determines the contribution of each ear to perceived elevation as function of sound azimuth. We demonstrated recently that binaural pinna molds virtually abolish the ability to localize sound-source elevation, but, after several weeks, subjects regained normal localization performance. It is not clear which processing stage underlies this remarkable plasticity, because the auditory system could have learned the new spectral cues separately for each ear (spatial-mapping adaptation) or for one ear only, while extending its contribution into the contralateral hemifield (binaural-weighting adaptation). To dissociate these possibilities, we applied a long-term monaural spectral perturbation in 13 subjects. Our results show that, in eight experiments, listeners learned to localize accurately with new spectral cues that differed substantially from those provided by their own ears. Interestingly, five subjects, whose spectral cues were not sufficiently perturbed, never yielded stable localization performance. Our findings indicate that the analysis of spectral cues may involve a correlation process between the sensory input and a stored spectral representation of the subject's ears and that learning acts predominantly at a spectral-to-spatial mapping level rather than at the level of binaural weighting.

Acoustic Stimulation↗

PubMed2004

Sound-induced motions of individual cochlear hair bundles.

We present motions of individual freestanding hair bundles in an isolated cochlea in response to tonal sound stimulation. Motions were measured from images taken by strobing a light source at the tone frequency. The tips and bases of hair bundles moved a comparable amount, but with a phase difference that increased by 180 degrees with frequency, indicating that distributed fluid properties drove hair bundle motion. Hair bundle rotation increased with frequency to a constant value, and underwent >90 degrees of phase change. The frequency at which the phase of rotation relative to deflection of the bundle base was 60 degrees was comparable to the expected best frequency of each hair cell, and varied inversely with the square of bundle height. The sharpness of tuning of individual hair bundles was comparable to that of hair cell receptor potentials at high sound levels. These results indicate that frequency selectivity at high sound levels in this cochlea is purely mechanical, determined by the interaction of hair bundles with the surrounding fluid. The sharper tuning of receptor potentials at lower sound levels is consistent with the presence of a negative damping, but not a negative stiffness, as an active amplifier in hair bundles.

Acoustic Stimulation↗

PubMed1977

Phono-, echo-, and electro-cardiographic correlation in the Wolff-Parkinson-White syndrome, with special reference to the split pattern of second heart sound.

Twenty-three cases with WPW syndrome were studied by means of phonocardiography, echocardiography, and electrocardiography. All cases showed the abnormal cardiac motion in echocardiography, which could be divided into 2 types; ventricular (V) type in which the posterior left ventricular wall showed the abnormal humps in the early and late systole (18 cases), and septal (S) type in which the abnormal hump was noted in the early systole in the interventricular septum (5 cases). The cases with V type echocardiogram showed either type A, B, or C, and those with S type either type B or C of ECG. All cases with V type had the splitting of second heart sound of a normal fashion and the IIA-IIP interval ranged from 0.015 to 0.08 sec with a mean of 0.0356+/-0.0157 sec. In contrast, those with S type showed either a reversed splitting of second heart sound (4 cases) or a single second heart sound (1 case), and the IIA-IIP interval ranged from 0 to--0.05 sec with a mean of --0.0250+/-0.0170 sec. No consistent relationship was noted between the ECG type and the split interval of second heart sound. There was the significant positive correlation between the IIA-IIP interval and the QRS duration in the cases with V type echocardiogram. In S type, these 2 parameters showed the significant negative correlation.

Adolescent↗

PubMed1981

The pulmonary component of the second heart sound in acquired aortic stenosis.

The amplitude of the pulmonic component of the second sound in aortic stenosis was studied in 49 patients with this lesion. As controls, 50 normal subjects were also studied. Both groups were investigated by phonocardiography, apex cardiography and arterial tracings. Nineteen patients with aortic stenosis and four subjects without it were also studied by cardiac catheterization and angiography. The amplitudes of the two components of the second sound were compared, and the ratio of each with the amplitude of the first sound was determined. The ratios of both the aortic and the pulmonic component to that of the first sound were decreased in aortic stenosis, and the decrease of the pulmonic component was comparable to that of the aortic component. These findings could be related to prolongation of the isovolumic relaxation period of both ventricles caused by an influence of the left ventricle on the right, most likely due to functional changes of the interventricular septum.

Adolescent↗

PubMed1990

A case of secundum atrial septal defect combined with aortic stenosis and coronary artery disease showing a single second heart sound.

We describe an extremely rare case of secundum atrial septal defect with aortic stenosis and coronary artery disease showing a single second heart sound throughout the respiratory cycle by echocardiogram with simultaneous phonocardiogram. Aortic valve closure corresponded to the single second heart sound. We were unable to detect pulmonary valve closure (PVC) on echocardiogram. Because of the presence of pulmonary hypertension, the pulmonary component of the second heart sound (P2) was presumed to be increased in intensity, and the PVC-P2 interval was thought to be abbreviated. Carotid pulse tracing showed a prolongation of the left ventricular ejection time. We concluded that the single second heart sound was due to both prolongation of left ventricular systole and pulmonary hypertension.

Aortic Valve Stenosis↗