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PubMed1977

[Contoursonagraphic analysis of heart sound phenomena and sounds produced by various heart valve prostheses].

The normal heart sounds, murmurs, opening and closing sounds of aortic and mitral valve prostheses were recorded on a tape and analyzed in terms of contour sonagrams in order to obtain the highest frequencies which were recordable on the chest wall. The peak frequencies showed a broad range, the maximum beeing reached at about 8000 c.p.s. in the case of the sounds of prosthetic valves. Furthermore, sound level examinations of the normal first and second heart sound, as well as of the opening and closing sounds of the aortic valve prostheses were performed. The highest sound level of all of these sounds was found to lie within the low frequency range of 40 to 100 c.p.s.

Aortic Valve Insufficiency↗

PubMed1975

First heart sound and ejection sounds. Echocardiographic and phonocardiographic correlation with valvular events.

To provide additional information on the relation of valvular events to the principal components of the first heart sound (s1), combined echocardiograms and phonocardiograms were recorded in 49 subjects, chosen because of audible splitting of S1 or a combination of S1 and an ejection sound. The subjects included 14 normal persons, 16 patients with a variety of predominantly right-sided heart conditions, 7 with mitral stenosis, 3 with pulmonary stenosis and 9 with aortic valve disease or systemic hypertension. A precise relation was found between completion of closure of the atrioventricular (A-V) valves manifested in the echocardiogram and the high-frequency components of S1 (M1 and T1). The average time from the Q wave of the electrocardiogram to M1 was 0.06 plus or minus 0.003 second and the Q-T1 interval was 0.09 plus or minus 0.002 second. In mitral stenosis the Q-M1 interval was delayed to 0.10 plus or minus 0.005 second, resulting in some instances in reversed splitting of S1. In pulmonary stenosis, the ejection sound occurred 0.10 plus or minus 0.003 second from the Q wave. In 7 of the 16 patients with various right-sided abnormalities, but without valvular stenosis, an ejection sound of pulmonary origin occurred 0.18 plus or minus 0.012 second from the Q wave. In the nine patients with aortic valve disease or systemic hypertension, the time from the Q wave to the aortic ejection sound was 0.13 plus or minus 0.004 second. With only two exceptions the ejection sounds of aortic and plumonary origin coincided exactly with achievement of a fully opened position of the respective semilunar valve. Our findings support the postulate that M1, T1 and the ejection sounds occur in association with closing or opening of valves with consequent sudden deceleration or acceleration of a column of blood that, in turn, results in vibrations of the cardiohemic system and audible sounds.

Adolescent↗

PubMed1999

Long-lasting enhancement of sound discrimination ability after sound exposure in rats.

Changes in the sound discrimination ability of rats were investigated after sound exposure (SE) in a Skinner box. For estimation of the sound discrimination ability, two different amplitude-modulated (AM) sounds (S+ and S-) were presented to the rats deprived of water for 48 h. Pedal press behavior in response to only S+ was rewarded with water. The percentages of trials in which pedal press behavior occurred in response to S+ or S- were calculated separately, and test performance of the rats was determined from the difference between the percentages. Rats were exposed to AM sounds during SE of 48 h, and the sound discrimination test was carried out. Enhancement of discrimination between S+ and S- was elicited by SE in a stimulus-specific manner. Latent extinction of the pedal press behavior in response to sound stimuli was not clearly found after SE. The enhancement of test performance was detected 1-48 h after the cessation of SE, and was blocked by injection of an antagonist of N-methyl-D-aspartate receptors into the auditory cortex bilaterally, immediately before the initiation of SE. These results suggest that SE elicits enhancement of sound discrimination ability, and the responsible site is in the auditory cortex.

Acoustic Stimulation↗

PubMed1995

Directional sound processing and interaural sound transmission in a small and a large grasshopper

Physical mechanisms involved in directional hearing are investigated in two species of short-horned grasshoppers that differ in body length by a factor of 34. The directional cues (the effects of the direction of sound incidence on the amplitude and phase angle of the sounds at the ears) are more pronounced in the larger animal, but the scaling is not simple. At high frequencies (1020 kHz), the sound pressures at the ears of the larger species (Schistocerca gregaria) differ sufficiently to provide a useful directionality. In contrast, at low frequencies (35 kHz), the ears must be acoustically coupled and work as pressure difference receivers. At 35 kHz, the interaural sound transmission is approximately 0.5 (that is, when a tympanum is driven by a sound pressure of unit amplitude at its outer surface, the tympanum of the opposite ear receives a sound pressure with an amplitude of 0.5 through the interaural pathway). The interaural transmission decreases with frequency, and above 10 kHz it is only 0.10.2. It still has a significant effect on the directionality, however, because the directional cues are large. In the smaller species (Chorthippus biguttulus), the interaural sound transmission is also around 0.5 at 5 kHz, but the directionality is poor. The reason for this is not the modest directional cues, but rather the fact that the transmitted sound is not sufficiently delayed for the ear to exploit the directional cues. Above 7 kHz, the transmission increases to approximately 0.8 and the transmission delay increases; this allows the ear to become more directional, despite the still modest directional cues.

Journal Article↗

PubMed1995

A study of temporomandibular joint sounds. Part 2. Acoustic characteristics of joint sounds.

In an attempt to gain a better understanding of temporomandibular joint (TMJ) sounds, we recorded joint sounds from 14 non-orthodontically treated dental students, analyzed the acoustic characteristics of the TMJ sounds, and correlated the sound characteristics with axiographic features, morphologic observations of X-ray images and clinical history. The group with a low peak frequency (< 500 Hz) of the opening click had a shorter history of subjective joint sound, a longer distance between the opening and closing curves, and a low rate of TMJ transformation. For the closing click, the history of subjective joint sounds tended to be longer when the duration of the wave was short. Acoustic analysis of TMJ sounds could be an aid to the differential diagnosis of temporomandibular disorders, although it is difficult to deduce the clinical history and internal deformities of the TMJ based solely on acoustic characteristics.

Auscultation↗

PubMed1984

Audibility of an artificial third heart sound in relation to its frequency, amplitude, delay from the second heart sound and the experience of the observer.

The possibility of detecting synthetic third heart sounds was studied. A special unit was used that added a sound to a previously recorded phonocardiogram. The sound could be changed in frequency, amplitude and delay from the second heart sound. Four groups of observers--cardiologists, residents, nurses and students--listened to 32 random examples. Detection rate increased with experience of the observer (p less than 0.0001) as well as with amplitude (p less than 0.0001), frequency (p less than 0.0001) and delay of the sound (p less than 0.05). The sensitivity was highest among the cardiologists, but the specificity was not different between the groups. Data from this study indicate that the audibility of the third heart sound depends on several important factors. The sound should usually be audible, but variability of results were considerable even among experienced cardiologists. A quantified phonocardiographic recording should be used for validation.

Cardiology↗

PubMed2006

Use of bedside sound generators by patients with tinnitus-related sleeping difficulty: which sounds are preferred and why?

CONCLUSIONS: Most tinnitus patients who have difficulty sleeping experience some improvement in sleep after short-term use of bedside sound generators (BSSGs), although this study does not allow conclusions to be drawn as to how much other factors contribute. Many patients seem to find BSSGs helpful in reducing autonomic arousal. Further research is needed, but these findings raise the possibility that the emotional effects of sound enrichment have an important role to play in improving sleep among tinnitus patients. OBJECTIVES: This study investigated which sounds out of the options available on BSSGs are commonly chosen by patients and the reasons behind these choices. It also aimed to provide an indication as to whether BSSGs improve sleep quality in the short term. PATIENTS AND METHODS: A consecutive series of 39 tinnitus clinic patients who made a subjective complaint of sleep disturbance took part in the study. All participants were given a Naturecare BSSG to use at night. The Pittsburgh Sleep Quality Index (PSQI) and a semi-structured interview were used as outcome measures. RESULTS: Among the 35 participants who attended for follow-up there was a significant improvement in PSQI scores (p=0.001). 'Brook' and 'birds' were the most popular sounds, while 'white noise' proved the least popular. Most BSSG users listened to one sound only and most said that they chose their sound because of a pleasant emotional effect. A minority gave the quality of sound or its perceived effect on tinnitus as a reason for their choice.

Acoustic Stimulation↗

PubMed1990

Interaction between tracheal sound and flow rate: a comparison of some different flow evaluations from lung sounds.

We simultaneously recorded tracheal sound and air flow from nine normal subjects (seven males and two females). Sound was picked up at the supra sternal notch with an air-coupled sensitive microphone held in a small airtight probe. Flow was measured at the mouth using a pneumotachograph Fleisch n degrees 2. Both sound and flow were directly digitized at a sampling rate of 5120 Hz and then divided in 128-sample blocks. For each sound block the frequency spectrum was computed using the fast Fourier transform. In order to evaluate instantaneous flow-rate from tracheal sounds we investigated eight methods divided in two groups of four. In the first group (i.e., reference curves methods), we assumed that a relationship existed between sound and flow and was thus reflected by the variations of certain parameters. We chose to use simple straightforward relationships, already known and published. We tested four different parameters. During a calibration phase, we built for each parameter P a reference curve representing the variations of P versus flow and being specific to each subject. Then, an unknown flow was evaluated in calculating P on a 128-sample block, and the reference curve gave the corresponding flow. In the second group, we made a hierarchial clustering analysis of sound spectra for revealing the frequency modifications, induced by the flow. We tested two kinds of spectra as well as two ways of associating a flow to a given cluster. This led us to four other methods for calculating the flow. All the eight methods but one gave a mean uncertainty in the measure of flow of about 15%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed2006

The sound of death rattle I: are relatives distressed by hearing this sound?

BACKGROUND: Death rattle is the noisy, rattling breathing that occurs in many dying patients. Health professionals intervene because the sound is said to distress attendant relatives. We found no formal study to confirm or refute relatives' distress, so we decided to ask the relatives. METHOD: Face-to-face semi-structured interviews with 27 bereaved relatives to investigate their experience of terminal care and what their response had been to the sound of death rattle if this had occurred. Interview transcripts were subjected to thematic content analysis. RESULTS: We found that almost half of the 12 relatives who had heard the sound of death rattle had been distressed by it. The others were either neutral about the sound or found it a helpful signal of impending death. CONCLUSION: We confirmed that some relatives do find it distressing to hear the sound of death rattle. However, our expectation that relatives are universally disturbed by this sound was unfounded. There is no justification for a 'blanket' approach to therapeutic intervention when death rattle occurs. A better understanding is required of how relatives make sense of the sound of death rattle.

Attitude to Death↗

PubMed1996

Studies of temporomandibular joint sounds; Part 4. Phase relations of TMJ sounds and jaw movement.

A study was conducted to investigate the timing relationship of temporomandibular joint (TMJ) sounds during mandibular movement, as evaluated by the location of the condyle, in relation to the articular fossa using axiograph recording. TMJ sounds during jaw opening and closing occurred over a wide range: opening sounds were observed within a range of 41-100% of maximum opening, while closing sounds occurred within 1-80% of maximum opening. In calculating the peak frequency of the joint sounds, it was noted that there was no correlation between the timing of the sound and its peak frequency. This study revealed that the acoustic characteristics of TMJ sounds may be unaffected by the location of the condyle.

Auscultation↗

PubMed1991

[Acoustical analysis of occlusal sound--transfer functions of oral cavities and characteristics of waveform of occlusal sound].

The purpose of this study is to clarify the acoustical characteristics of the occlusal sound. An FFT analyzer was used to analyze the transfer functions of the oral cavities. The characteristics of the waveform of the occlusal sound were investigated by the time-frequency analysis. The results obtained were as follows: (1) There were three peaks in the low frequency area of the transfer functions of the oral cavities. The duration of the impulse responses of the oral cavities had a wide variation among the individuals. (2) The waveform of the occlusal sound by air-conduction was proved to consist of two components. One was the teeth collision sound produced by the collision of the teeth in the oral cavity and emitted directly out from the oral cavity. The other was the reverberation considered to be formed mainly by the resonance system in the oral cavity. (3) By the time-frequency analysis, the teeth collision sound could be distinguished clearly from the reverberation; the former was recognized as the component where the energy existed up to the high frequency area, while the latter was recognized as the component where the energy existed only in the low frequency area. (4) It was suggested that the teeth collision sound, after separating from the reverberation, should be analyzed for the purpose of obtaining further information about the functional condition of the occlusion from the occlusal sound.

Adult↗

PubMed2006

A robust method for heart sounds localization using lung sounds entropy.

Heart sounds are the main unavoidable interference in lung sound recording and analysis. Hence, several techniques have been developed to reduce or cancel heart sounds (HS) from lung sound records. The first step in most HS cancellation techniques is to detect the segments including HS. This paper proposes a novel method for HS localization using entropy of the lung sounds. We investigated both Shannon and Renyi entropies and the results of the method using Shannon entropy were superior. Another HS localization method based on multiresolution product of lung sounds wavelet coefficients adopted from was also implemented for comparison. The methods were tested on data from 6 healthy subjects recorded at low (7.5 ml/s/kg) and medium 115 ml/s/kg) flow rates. The error of entropy-based method using Shannon entropy was found to be 0.1 +/- 0.4% and 1.0 +/- 0.7% at low and medium flow rates, respectively, which is significantly lower than that of multiresolution product method and those of other methods reported in previous studies. The proposed method is fully automated and detects HS included segments in a completely unsupervised manner.

Adult↗

PubMed1998

Effect of sound familiarity on the event-related potentials elicited by novel environmental sounds.

The effect of sound familiarity was examined within the context of an event-related potential (ERP) novelty oddball paradigm. Brain electrical activity was recorded while subjects (16 young adults) listened to frequent tones, infrequent target tones, and infrequent novel environmental sounds. Subjects were instructed to press a button in response to the target tones only. There were 48 different novel sounds, 32 of which were repeated, and about two-thirds of which represented familiar sound concepts. The novel sounds elicited two ERP components, the novelty P3 and the P32. The novelty P3 was modulated by both repetition and familiarity, such that repeated familiar sounds elicited decreased novelty P3 amplitude at frontal sites, while repeated unfamiliar sounds elicited increased novelty P3 amplitude at posterior sites. This differential effect may reflect the operation of a neural network that distinguishes among different degrees of novelty.

Adult↗

PubMed1986

Sound spectral analysis of voice-transmitted sound.

There is a change in voice-generated sound heard over an area of pulmonary consolidation described as the "e" to "a" change. The lung may act as a low pass filter with properties that are changed by consolidation. We studied 5 patients with pneumonia. Using an electronic stethoscope, we recorded the voice-generated sounds "e" and "9-9-9." Sound spectral analysis using the fast Fourier transformation technique was used to characterize the frequency spectrum of the recorded sound. This technique allowed us to evaluate the filter properties of the normal and consolidated lung. We found that the normal lung allowed transmission of sound as high as 250 Hz with a gradual cutoff by 400 Hz. The consolidated lung allowed transmission of sound of a higher frequency; however, there was no significant transmission of sound with a frequency higher than 1,000 Hz.

Auscultation↗

PubMed2004

The role of phase changes in sound signals in localization of sound sources.

The auditory system in humans and animals makes virtually no discrimination of phase changes in the structure of monaurally presented sound signals. However, electrophysiological studies have demonstrated marked changes in the responses of the central parts of the auditory system when the phase structure of the signal changes during presentation of the same type of stimulation. We have suggested that this inconsistency is due to the preparative role of phase effects during monaural stimulation for subsequent operations in the auditory system involved in determining the location of a sound source in space. This report presents experimental data on defined changes (increases in amplitude) in the electrical responses of the midbrain center of the auditory system (inferior colliculus) in antiphase binaural presentation of series of sound impulses (comparison with synphase presentation). These changes may be part of the mechanism underlying the interference resistance of the auditory system during determination of the location of a sound source (binaural release from masking). Neuronal cortical activity is sensitive and selective to dynamic interaural changes in the phase spectrum of the signal, which may provide the basis of the mechanism for locating a moving sound source. Auditory evoked potentials in humans demonstrate memorizing of the direction of movement of a sound image, as shown by the changes in parameters on presentation of stimuli of different locations (deviant stimuli) differing from the standard parameters of mismatch negativity.

Acoustic Stimulation↗

PubMed1998

The physiologic cause of swallowing sounds: answers from heart sounds and vocal tract acoustics.

A hypothetical discussion of the cause of swallowing sounds is presented. It is suggested that the pharynx contains a number of valves and pumps that produce reverberations within the pharynx to generate swallowing sounds. As heart sounds are propagated via vibration of muscles and valves, it is further suggested that an analogy exists between the generation of heart sounds and swallowing sounds. This new theory is known as the cardiac analogy hypothesis. The inability of the current literature to explain the cause of swallowing sounds is seen to limit the diagnostic potential of cervical auscultation for dysphagia assessment. Future investigators are encouraged to prove or disprove the cardiac analogy hypothesis.

Acoustics↗

PubMed1992

Infants' perception of illusions in sound localization: reaching to sounds in the dark.

Sixteen infants each at 4, 6, and 8 months of age were tested for reaching to sounding toys in the dark under two auditory illusion conditions: the Haas-effect, which creates the illusion of a single lateralized sound based on an interaural intensity difference (the toy was visible and invisible under some test conditions); and the midline illusion, which creates the illusion of a single sound at midline due to an absence of any interaural time or intensity differences (invisible toy condition only). No-sound control trials indicated the level of spontaneous reaching in the dark. Results indicate that by 4 months infants perceive both the Haas-effect and midline illusions. The ability to reach both for invisible and visible sounding objects in the dark was well developed by 4 months of age, although developmental changes in aspects of reaching behavior were observed and, at all ages, object contact was most frequent when visual localization cues accompanied sound localization cues. The incidence of spontaneous reaching in the dark was low and did not vary with age. Theoretical and methodological implications of this research are discussed.

Acoustic Stimulation↗

PubMed1985

Maternal vocalisations and other sounds in the fetal lamb's sound environment.

In a first experiment a miniaturised radio hydrophone was implanted inside the amniotic sac in three pregnant ewes and recordings were made from 3 weeks before the lambs were born until they had emerged; these recordings showed that the sound of the mother's voice was slightly louder when picked up by the hydrophone inside the amniotic sac than when picked up by a microphone beside her flank and that sounds recorded during labour included long and loud low frequency sounds associated with contractions, and an increase, compared with before labour, in the incidence of sounds produced by the maternal cardiovascular system and by breathing. Over the last 3 weeks of gestation the attenuation of sounds from outside the mother decreased at frequencies between 500 and 4000 Hz, but not below or above those frequencies. In a second experiment the bleats of 23 pregnant ewes were recorded; their lambs were taken at birth and tested with the sound of either their own mother's bleats, or with bleats from an alien ewe. Heart rate changes which occurred during playback of maternal and alien bleats differed significantly, but only on the occasion when each lamb heard its first bleat, postnatally.

Animals↗