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At least 973 records · Page 54Linked to original sources
PubMed1976

The contribution of tricuspid valve closure to the first heart sound. An intracardiac micromanometer study.

The sound-pressure correlates of the second high frequency component of a split first heart sound (S1) were investigated in 27 patients. An external phonocardiogram was recorded with high fidelity sound and pressure from the left and right atria in 21 patients, from the pulmonary artery in 14 of these, and from the central aorta in 11. In the remaining six patients, high fidelity recordings from the central aorta and right-sided chambers were obtained with an external phonocardiogram. The external component of S1 that coincided with a left atrial C wave and "internal sound" was defined as M1. In those cases where the left atrial pressure was not recorded, this component could be identified by a low frequency transient in the central aortic pressure trace. The other external high frequency component of S1 that was synchronous with a separate right atrial C wave and "internal sound" was defined as T1; with two exceptions, M1 preceded T1. The two exceptions which caused reversal of this order, so that T1 preceded M1, were due to chronic left bundle branch block and mitral stenosis. In both cases, T1 was shown to be distinctly separated from the upstroke of pressure rise in the central aorta. This finding was also demonstrated in three cases of right bundle branch block and one case with aortic valvular disease. The usual asynchrony of ventricular contraction was altered by induction of ventricular premature systoles; the separation of externally identifiable M1 and T1 components and their internal markers was predictably altered by this maneuver. The occurrence of T1 was variable in relation to the upstroke of the pulmonary artery pressure, which suggests that it is not related to pulmonic ejection. It is concluded that micromanometrically recorded right and left atrial C waves can serve as markers for externally recordable M1 and T1 components of the first heart sound. In addition, T1 is frequently an externally recordable and audible event.

Adolescent↗
PubMed1977

The aortic closure sound in pure aortic insufficiency.

The second sound in aortic insufficiency has been described as accentuated, normal, or moderately diminished. A study of intracardiac phonocardiograms was performed to evaluate its intensity and to eliminate extracardiac factors. Pressure and intracardiac sound measurements were made in 28 patients undergoing diagnostic cardiac catheterization. Recordings were obtained above the aortic valve and within the left ventricle in 14 patients with normal aortic valves and 11 patients with aortic insufficiency uncomplicated by aortic stenosis. The amplitude of the aortic closure sound in the patients with pure aortic insufficiency, 1000 +/- 100 dynes/cm2, was significantly lower than in those patients with normal aortic valves, 3100 +/- 200 dynes/cm2 (P less than 0.001). The results indicate, therefore, that the presence of aortic insufficiency causes a diminished amplitude of the aortic closure sound. These results are supportive of the theory that the second heart sound is caused by diastolic vibrations of the closed aortic cusps. Diminished valvular vibrations and sound would occur in pure aortic insufficiency if the valve is unable to properly tense during diastole, or if the rate of development of the driving pressure is diminished.

Aortic Valve↗
PubMed1999

Tissue characterization of myocardial cells by use of high-frequency acoustic microscopy: differential myocyte sound speed and its transmural variation in normal, pressure-overload hypertrophic, and amyloid myocardium.

The purpose of the present study was to evaluate the acoustic properties of myocytes in normal, pressure-overload hypertrophic, and amyloid myocardium. Myocardial tissue specimens at autopsy were obtained from 10 subjects without cardiovascular disease, six patients with left ventricular (LV) hypertrophy, and six patients with cardiac amyloidosis. Sound speed of myocytes was measured at subendocardial and subepicardial regions in myocardium by use of a high-frequency (450 MHz) acoustic microscope. In normal myocardium, the sound speed of myocytes was significantly higher in subendocardial region (1,728+/-19 m/sec) than in subepicardial region (1,645+/-22 m/sec) (p<0.0001). A significantly higher sound speed of myocytes was observed in the subendocardial region in LV hypertrophic myocardium (1,779+/-19 m/sec) than that in normal myocardium (p<0.001). In amyloid myocardium, a significantly lower sound speed of myocytes was observed in subendocardial (1,560+/-8 m/sec) and subepicardial (1,594+/-48 m/sec) regions than that in respective regions of the normal myocardium (p<0.0001 and p<0.05, respectively). Transmural variation in sound speed of myocytes measured by high-frequency acoustic microscopy existed in normal left ventricle. The differential myocyte sound speed and its transmural variation was observed in LV hypertrophic and amyloid myocardium as compared with normal myocardium. High-frequency acoustic microscopy can be a promising technique for myocardial tissue characterization at the myocyte level.

Acoustics↗
PubMedDate not supplied

Sound-symbol learning in children with dyslexia.

This study evaluated the effect of sound-symbol association training on visual and phonological memory in children with a history of dyslexia. Pretests of phonological and visual memory, a sound-symbol training procedure, and phonological and visual memory posttests were administered to children with dyslexia, to children whose dyslexia had been compensated through remedial training, and to age- and reading level-matched comparison groups. Deficits in visual and phonological memory and memory for sound-symbol associations were demonstrated in the dyslexia group. For children with dyslexia and children whose dyslexia had been remediated, the sound-symbol training scores were significantly associated with word and pseudoword reading scores and were significantly lower than those of the comparison groups. Children with dyslexia and children whose dyslexia had been compensated showed significantly less facilitation of phonological memory following the training than did typical readers. Skilled readers showed some reduction in accuracy of visual memory following the training, which may be the result of interference of verbalization with a predominantly visual task. A parallel decrease was not observed in the children with dyslexia, possibly because these children did not use the verbal cues. Children with dyslexia and children whose dyslexia had been compensated seemed to have difficulty encoding the novel sounds in memory. As a result, they derived less phonological memory advantage and less visual memory interference from the training than did typical readers. Children in the compensated dyslexia group scored lower on sound-symbol training than their age peers. In other respects, the scores of these children were equivalent to those of the typically reading comparison groups. Children in the compensated dyslexia group exhibited higher phonological rehearsal, iconic memory, and associative memory scores than children in the dyslexia group. Implications for the remediation of dyslexia are discussed.

Auditory Perception↗
PubMed2005

Vestibular responses to sound.

Research into vestibular responses to sound has evolved in four stages. The first, largely the work of Tullio in the 1920s, involved inspection of the eye, head, and postural responses to sound of alert animals with surgical fenestrae into various parts of the bony labyrinth. The second, begun in 1964 by Bickford and his group and continued by our group and then by others in the last 10 years, involves the measurement of evoked myogenic potentials to air-conducted and bone-conducted clicks and tones in normal humans. The third, begun by Mikaelian at about the same time as Bickford and continued by McCue, our group, and others, involves electrophysiological recordings of primary vestibular afferent neuron responses to sound in anesthetized animals. The fourth involves measurements of vestibulo-ocular responses to sound in humans with the Tullio phenomenon. It was begun by Minor and his group in 1998 with the observation that sound-induced nystagmus in humans, the Tullio phenomenon, aligned with the rotation axis of the superior semicircular canal. They then showed a defect in the temporal bone between the apex of the superior semicircular canal and the middle cranial fossa, which was the cause of most, if not all, cases of sound-induced nystagmus. Here some of the key observations made in each of these four stages are reviewed.

Acoustic Stimulation↗
PubMed2006

Dolphin foraging sounds suppress calling and elevate stress hormone levels in a prey species, the Gulf toadfish.

The passive listening hypothesis proposes that dolphins and whales detect acoustic signals emitted by prey, including sound-producing (soniferous) fishes. Previous work showed that bottlenose dolphins (Tursiops truncatus) behaviorally orient toward the sounds of prey, including the advertisement calls of male Gulf toadfish (Opsanus beta). In addition, soniferous fishes constitute over 80% of Tursiops diet, and toadfishes alone account for approximately 13% of the stomach contents of adult bottlenose dolphins. Here, we used both behavioral (vocalizations) and physiological (plasma cortisol levels) parameters to determine if male Gulf toadfish can, in turn, detect the acoustic signals of bottlenose dolphins. Using underwater playbacks to toadfish in their natural environment, we found that low-frequency dolphin sounds (;pops') within the toadfish's range of hearing dramatically reduce toadfish calling rates by 50%. High frequency dolphin sounds (whistles) and low-frequency snapping shrimp pops (ambient control sounds) each had no effect on toadfish calling rates. Predator sound playbacks also had consequences for circulating stress hormones, as cortisol levels were significantly elevated in male toadfish exposed to dolphin pops compared with snapping shrimp pops. These findings lend strong support to the hypothesis that individuals of a prey species modulate communication behavior in the presence of a predator, and also suggest that short-term glucocorticoid elevation is associated with anti-predator behavior.

Acoustics↗
PubMed1997

In situ biomechanics of the syrinx and sound generation in pigeons.

The in situ biomechanics of the vocal organ, the syrinx, was studied in anesthetized pigeons using fiberoptic instruments. The role of syringeal muscles was determined by electrical stimulation, and phonation was induced by injecting gas into the subsyringeal air sacs. This study presents the first direct observations of the biomechanical processes that occur in an intact syrinx. Contraction of one of the syringeal muscles, the m. tracheolateralis (TL), withdraws the lateral tympaniform membranes (LTM) from the syringeal lumen, causing opening of the syringeal airways. Shortening of a second muscle, the sternotrachealis (ST), draws the syringeal cartilages closer to each other, causing the LTM to fold into the syringeal lumen. Maximal ST contraction does not lead to complete closure of the syrinx. As air-sac pressure is increased by the injection of gas, the LTM are drawn into the syringeal lumen and balloon in a rostral direction until they touch, thus forming a fold-like valve. Air-induced phonation is always associated with vibrations of the membrane folds, suggesting that pulsatile release of air into the trachea by vibratory motion of the LTM generates sound. During air-induced phonation, strong stimulation of the TL terminates sound generation by abducting the LTM, whereas weak stimulation changes the geometry of the membrane folds, which is accompanied by changes in the acoustic structure of the sound. Stimulation of the ST has little effect on air-induced sounds. The LTM appear to be the main sound generators, since disabling the medial tympaniform membranes (MTM) with tissue adhesive does not prevent phonation or change the frequency and amplitude structure of display coos in spontaneously vocalizing pigeons. Moreover, the activity of the syringeal muscles appears to have a mainly modulatory function, suggesting that the basic sound-generating mechanism is similar in both air-induced and natural phonation.

Air↗
PubMed2002

Response of western diamondback rattlesnakes Crotalus atrox to airborne sounds.

In order to test the hypothesis that snakes can not only perceive airborne sounds, but also respond to them, an acoustic isolation chamber was designed and constructed to perform best within the 150-450 Hz range in which snakes perceive sound. Suspended within this acoustic chamber was a steel mesh basket designed to minimize the potential for groundborne vibrations. A synthesized tone was created out of 20 different 150 ms sounds, each separated by a 50 ms period of silence; the acoustic energy of each of the 20 sounds was concentrated between 200-400 Hz, and each sound included frequency modulation. The trial stimuli were presented to western diamondback rattlesnakes Crotalus atrox at a level 5-10 dB above their perception threshold. Four significant behavioural responses were observed upon stimulus presentation: cessation of body movements, reduction or cessation of tongue flicking, rapid jerks of the head and rattling. At least one significant behavioural response was observed in 92% of the behavioural trials. This study provides the first experimental evidence that snakes can respond behaviourally to airborne sounds.

Animal Communication↗
PubMed1996

Sound stimulation-induced vasomotor reflex in the central artery of the rabbit ear.

Effects of sound stimulation on the central artery of the rabbit ear were studied as a somato-autonomic reflex. Vasoconstriction and dilatation, caused by metronome sound stimulation, were estimated from the temperature fluctuations in the central artery of the ear, measured by a thermistor. To enhance the detection of temperature rises, moderately high background levels of arterial tone were established by exposing the tips of the ears to water at a temperature of 10 degrees C or 5 degrees C, prior to sound stimulation. A fall in arterial temperature due to vasoconstriction was observed immediately after the start of the 1-min sound stimulation, with a subsequent temperature rise which overshot the original basal level due to vasodilatation. A positive correlation between the ear temperature before sound stimulation and the temperature fall (p < 0.01), and a negative correlation between the ear temperature and the temperature rise (p < 0.05) were obtained. The temperature fall was blocked by phenoxybenzamine (9 mg/kg, i.p., p < 0.01). The subsequent rise was not influenced by atropine (3 mg/kg, i.p.) or phenoxybenzamine, however, it was attenuated by hexamethonium (6 mg/kg, i.p., p < 0.05). The temperature fall at the beginning of sound stimulation was related to alpha-adrenergic mechanism. The subsequent temperature rise was thought to be related to parasympathetic mechanism, excluding cholinergic mechanism.

Acoustic Stimulation↗
PubMed1994

Use of furcal bone sounding to improve accuracy of furcation diagnosis.

Accurate diagnosis of periodontal destruction in the furcation region of multi-rooted teeth is a critical component of treatment planning, with different therapeutic approaches chosen based upon clinical determination of the severity of involvement. The current study assessed both vertical and horizontal depths of 274 furcations from 67 patients at three separate time points: by probing prior to anesthesia, by bone sounding after administration of anesthesia, and by direct measurement at the time of surgery. All measurements were made to the nearest millimeter. The mean vertical (1.8 mm) and horizontal (2.16 mm) furcation depths determined prior to anesthesia were significantly less than surgical measurements (2.79 mm and 3.65 mm, respectively). Use of sounding significantly improved the mean accuracy of vertical (2.40 mm) and horizontal (3.11 mm) furcation depth measurements relative to surgical determinations (P = 0.000). Surgical vertical depth was exactly the same as pre-anesthesia probing in 42% of furcations, within +/- 1 mm in 72.3% and within +/- 2 mm in 83.6%. Use of post-anesthesia sounding improved agreement in vertical measurements to 59.5%, 85.7%, and 93.1%, respectively. Surgical horizontal depth was exactly the same as pre-anesthesia probing measurements in 47.1% of furcations, within +/- 1 mm in 68.3% and within +/- 2 mm in 77.4%. Sounding improved agreement of horizontal measurements to 64.2%, 83.6%, and 88.3%, respectively. Underestimation of surgical furcation depths by pre-anesthesia probing was much more common than overestimation. Sounding reduced the percent and degree of underestimation in all furcation types. The data demonstrate the ability of post-anesthesia bone sounding to significantly improve the diagnostic accuracy of furcation invasions.

Adult↗
PubMed1989

[Analysing noise levels in dental environment. Air turbine sound response to various physical factors].

Dental Air Turbine sound depends on the mechanical performance such as rotation and it is impossible to neglect connections of the sound with fluid mechanics and acoustics. Turbine sound must be considered from the standpoint of the sound pressure level and frequency component. In this study, the sound samples was measured and analysed in octave band spectrum. Turbine sound has three resonance bands of the frequency with the range from 0 to 1,600 Hz and the resonance band increased as air pressure increased. The frequency of the second resonance band decreased as the cutting load and cutting point diameter increased. Damping of the second resonance band frequency shifted downward by polishing point.

Dental High-Speed Equipment↗
PubMed2002

Improving the classroom listening skills of children with Down syndrome by using sound-field amplification.

Many children with Down syndrome have fluctuating conductive hearing losses further reducing their speech, language and academic development. It is within the school environment where access to auditory information is crucial that many children with Down syndrome are especially disadvantaged. Conductive hearing impairment which is often fluctuating and undetected reduces the child's ability to extract the important information from the auditory signal. Unfortunately, the design and acoustics of the classroom leads to problems in extracting the speech signal through reduced speech intensity due to the increased distance of the student from the teacher in addition to masking from excessive background noise. One potential solution is the use of sound-field amplification which provides a uniform amplification to the teacher's voice through the use of a microphone and loudspeakers. This investigation examined the efficacy of sound-field amplification for 4 children with Down syndrome. Measures of speech perception were taken with and without the sound-field system and found that the children perceived significantly more speech in all conditions where the sound-field system was used (p < .0001). Importantly, listening performance with the sound-field system was not affected by reducing the signal-to-noise ratio through increasing the level of background noise. In summary, sound-field amplification provides improved access to the speech signal for children with Down syndrome and as a consequence leads to improved classroom success.

Amplifiers, Electronic↗
PubMedDate not supplied

Effect of vasodilating agents on cochlear blood flow under loud sound exposure.

Loud sound has been proved by means of laser Doppler flowmetry to decline cochlear blood flow. The purpose of this study was to investigate the effect of a vasodilating agent on cochlear blood flow under loud sound exposure, i.e. whether the drug can impede blood flow decrease or not. As a vasodilating agent, dilazep dihydrochloride in a dose of 5 mg/kg was used. This drug caused a stable and significant increase of cochlear blood flow when intravenously injected into guinea pigs. When guinea pigs were exposed to loud sound (120 dB SPL at 10 kHz) for 10 min, cochlear blood flow promptly declined at the onset of sound stimulation and promptly recovered at its cessation. Then, dilazep dihydrochloride 5 mg/kg was injected intravenously into the same animal and loud sound (120 dB SPL at 10 kHz) was exposed for 10 min. Dilazep did not fully block a prompt decline of cochlear blood flow. However, the blood flow level was kept much higher than at pre-injection level. This study shows that a vasodilating agent which normally enhances blood flow probably does not completely block the sound-induced drop response in cochlear blood flow.

Animals↗
PubMed1981

The effect of hearing protectors on the attention demand of warning sounds.

A reason often given by noise-exposed workers for not wearing their hearing protection is that it impairs their ability to hear important sounds such as acoustic warning signals. An experiment was therefore conducted to assess the possible effect of wearing hearing protection on the attention demand of a typical industrial warning sound. Inattention was created by providing uncertainty as to the time occurrence of the signal, and a separate loading task. The results indicate that neither inattention, nor the combination of inattention and the wearing of hearing protection, need necessarily impair the perception of a warning sound. The experiment therefore found no basis for the attitude that hearing protectors impair the effectiveness of warning sounds. This conclusion may not however apply to warning sounds which are not distinct from the ambient noise, those which have to be recognized amongst other discrete sounds, or to users of hearing protection with an existing noise-induced hearing loss.

Adult↗
PubMed2005

The seasonality of fecal coliform bacteria pollution and its influence on closures of shellfish harvesting areas in Mississippi Sound.

Runoff from agricultural lands and farm animal feedlots is one of the major sources of fecal coliforms in surface waters, and fecal coliform (FC) bacteria concentrations tend to vary with season because of seasonal variations in climatic factors. However, El Niño--Southern Oscillation (ENSO) events may affect the extent and patterns of seasonality in FC levels in coastal waters. Water quality monitoring data for shellfish management collected during El Niño (1990, 1992, 1997), and La Niña (1999, 2000) years were analyzed to evaluate the extent to which these events influenced Pearl River stage, and bacterial levels, water temperature, and salinity in the western part of Mississippi Sound. Models to predict FC levels in relation to various environmental factors were also developed. In 1990, 1992 and 1997, FC geometric mean counts peaked in late winter (January/February) reaching 120 MPN (February 1990), 165 MPN (January 1992), and 86 MPN (January 1997), and then decreased considerably during spring and summer (1.2 - 19 MPN). Thereafter, FC abundance increased slightly in fall and early winter (1.9 - 24 MPN). Fecal coliform abundance during the 2000 La Niña year was much lower (1.0 -10.3 MPN) than in 1992 (1.2 - 165 MPN), and showed no seasonal pattern from January to August, perhaps due to the relative scarcity of rainfall in 2000. In 1995 (ENSO neutral year), peak geometric mean FC count (46 MPN) was lower than during El Niño years and occurred in early spring (March). The seasonal and between year variations in FC levels determined the number of days during which the conditionally approved shellfish growing area was opened for harvesting shellfish. For example, from January to April 1997, the area was not opened for shellfish harvesting, whereas in 2000, the number of days during which the area was opened ranged from 6 - 27 (January to April) to 24 - 26 (October to December). ENSO events thus influenced the extent and timing of the peak levels of fecal coliforms in Mississippi Sound. Models consisting of one or more of the variables: Pearl River stage, water temperature, and salinity were developed to predict FC concentrations in the Sound. The model parameter(s) explained 56 to 91% of the variations in FC counts. Management of shellfish in Mississippi Sound can be improved by utilizing information on the forecasted three to seven years occurrence of ENSO events. In addition, since Pearl River stage was the most important variable predicting FC concentration in the Sound, a study of the levels and sources of FC bacteria in the river, especially the middle and lower sections, is needed for developing a management plan for reducing FC bacteria pollution in the Sound.

Colony Count, Microbial↗
PubMed2003

Do video sounds interfere with auditory event-related potentials?

To make the electroencephalogram (EEG) recording procedure more tolerable, listeners have been allowed in some experiments to watch an audible video while their auditory P1, N1, P2, and mismatch negativity (MMN) event-related potentials (ERPs) to experimental sounds have been measured. However, video sounds may degrade auditory ERPs to experimental sounds. This concern was tested with 19 adults who were instructed to ignore standard and deviant tones presented through headphones while they watched a video with the soundtrack audible in one condition and silent in the other. Video sound impaired the size, latency, and split-half reliability of the MMN, and it decreased the size of the P2. However, it had little effect on the P1 or N1 or on the split-half reliability of the P1-N1-P2 waveform, which was significantly more reliable than the MMN waveform regardless of whether the video sound was on or off. The impressive reliability of the P1 and N1 components allows for the use of video sound during EEG recording, and they may prove useful for assessing auditory processing in listeners who cannot tolerate long testing sessions.

Acoustic Stimulation↗
PubMed2003

[Development of a computerized sound attenuation measurement system of hearing protectors based on Japanese Industrial Standard(JIS)].

Sound attenuation measurement of hearing protectors is done in accordance with JIS T 8161 in Japan. In the JIS T 8161 it is stated that more than three non-coherent sets which include a noise generator, one-third octave band-pass filter, amplifier, calibrated attenuator and signal interrupter are required. To realize this measurement system, various expenses and a large space are required. In our study, four channel test signals were generated by our programs, and fed to a digital/analog converter. Consequently, the hardware of a noise generator and one-third octave band-pass filter could be reduced. Moreover, a program, which automatically controlled sound pressure level by digitally controlled attenuators, was developed with the result that the sound attenuation measurement could be performed by operating the mouse. Furthermore, sound attenuation of the earplug was measured in accordance with JIS T 8161 to evaluate our system. The result showed that practical sound attenuation values were obtained by easy operation. It was considered that this system was effective in hardware reduction, and useful for sound attenuation measurement of hearing protectors.

Adolescent↗
PubMed1986

[Measurement of knee joint sounds by microphone].

The use of a microphone to detect sound emitted from knee joint and tissues is a significant advance on acoustic detection systems. All possible artifact signals encountered by the sound detection technique were investigated. Background noise is minimized by measuring in an anechoic chamber. Coupler noise is eliminated by ventilation holes. Skin friction noise is effectively eliminated using ultrasonic-gel. The use of a double microphone with differential amplifier to subtract the signals between two microphones is not suitable for the measurement of knee joint sound, because of the appearance of peak and dip frequency in a spectrum. It is possible to obtain the actual spectrum of knee joint sound by subtracting the spectrum of background sound from the spectrum of recorded knee joint sound.

Auscultation↗