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PubMed2001

On the annoyance caused by impulse sounds produced by small, medium-large, and large firearms.

A laboratory study was designed in which the annoyance was investigated for 14 different impulse sound types produced by various firearms ranging in caliber from 7.62 to 155 mm. Sixteen subjects rated the annoyance for the simulated conditions of (1) being outdoors, and (2) being indoors with the windows closed. In the latter case, a representative outdoor-to-indoor reduction in sound level was applied. It was anticipated that the presumed additional annoyance caused by the "heaviness" of the impulse sounds might be predicted from the difference between the C-weighted sound exposure level (CSEL; LCE) and the A-weighted sound exposure level (ASEL; LAE). In the outdoor rating conditions, the annoyance was almost entirely determined by ASEL. The explained variance, r2, in the mean ratings by ASEL was 0.95. In the indoor rating conditions, however, the explained variance in the annoyance ratings by (outdoor) ASEL was significantly increased from r2 = 0.87 to r2= 0.97 by adding the product (LCE-LAE)(LAE-alpha) as a second variable. In combination with a 12-dB adjustment for small firearms, the present results showed that for the entire set of impulse sounds rated indoors with windows closed, the rating sound level, Lr, is given by Lr=LAE +12dB+beta(LCE-LAE)(LAE-alpha), with alpha=45dB and beta=0.015dB(-1). For the outdoor rating condition, the optimal parameter values were equal to alpha=57 dB and, again, beta=0.015 dB(-1). In validation studies, in which the effects of the present rating procedure will be compared to field data, it has to be determined to what extent the constants alpha and beta have to be adjusted.

Adolescent↗
PubMed2001

Formant-frequency matching between sounds with different bandwidths and on different fundamental frequencies.

The two experiments described here use a formant-matching task to investigate what abstract representations of sound are available to listeners. The first experiment examines how veridically and reliably listeners can adjust the formant frequency of a single-formant sound to match the timbre of a target single-formant sound that has a different bandwidth and either the same or a different fundamental frequency (F0). Comparison with previous results [Dissard and Darwin, J. Acoust. Soc. Am. 106, 960-969 (2000)] shows that (i) for sounds on the same F0, introducing a difference in bandwidth increases the variability of matches regardless of whether the harmonics close to the formant are resolved or unresolved; (ii) for sounds on different F0's, introducing a difference in bandwidth only increases variability for sounds that have unresolved harmonics close to the formant. The second experiment shows that match variability for sounds differing in F0, but with the same bandwidth and with resolved harmonics near the formant peak, is not influenced by the harmonic spacing or by the alignment of harmonics with the formant peak. Overall, these results indicate that match variability increases when the match cannot be made on the basis of the excitation pattern, but match variability does not appear to depend on whether ideal matching performance requires simply interpolation of a spectral envelope or also the extraction of the envelope's peak frequency.

Adult↗
PubMed2002

Linking the sounds of dolphins to their locations and behavior using video and multichannel acoustic recordings.

It is difficult to attribute underwater animal sounds to the individuals producing them. This paper presents a system developed to solve this problem for dolphins by linking acoustic locations of the sounds of captive bottlenose dolphins with an overhead video image. A time-delay beamforming algorithm localized dolphin sounds obtained from an array of hydrophones dispersed around a lagoon. The localized positions of vocalizing dolphins were projected onto video images. The performance of the system was measured for artificial calibration signals as well as for dolphin sounds. The performance of the system for calibration signals was analyzed in terms of acoustic localization error, video projection error, and combined acoustic localization and video error. The 95% confidence bounds for these were 1.5, 2.1, and 2.1 m, respectively. Performance of the system was analyzed for three types of dolphin sounds: echolocation clicks, whistles, and burst-pulsed sounds. The mean errors for these were 0.8, 1.3, and 1.3 m, respectively. The 95% confidence bound for all vocalizations was 2.8 m, roughly the length of an adult bottlenose dolphin. This system represents a significant advance for studying the function of vocalizations of marine animals in relation to their context, as the sounds can be identified to the vocalizing dolphin and linked to its concurrent behavior.

Acoustics↗
PubMed2002

Microphone array measurement system for analysis of directional and spatial variations of sound fields.

A measurement system has been developed that is capable of analyzing the directional and spatial variations in a reverberant sound field. A spherical, 32-element array of microphones is used to generate a narrow beam that is steered in 60 directions. Using an omnidirectional loudspeaker as excitation, the sound pressure arriving from each steering direction is measured as a function of time, in the form of pressure impulse responses. By subsequent analysis of these responses, the variation of arriving energy with direction is studied. The directional diffusion and directivity index of the arriving sound can be computed, as can the energy decay rate in each direction. An analysis of the 32 microphone responses themselves allows computation of the point-to-point variation of reverberation time and of sound pressure level, as well as the spatial cross-correlation coefficient, over the extent of the array. The system has been validated in simple sound fields in an anechoic chamber and in a reverberation chamber. The system characterizes these sound fields as expected, both quantitatively from the measures and qualitatively from plots of the arriving energy versus direction. It is anticipated that the system will be of value in evaluating the directional distribution of arriving energy and the degree and diffuseness of sound fields in rooms.

Amplifiers, Electronic↗
PubMed2003

Reliability of sound attenuation in Florida scrub habitat and behavioral implications.

Attenuation over distance in natural habitat is often difficult to predict when measured without respect to sound frequency. The physical-acoustic structure of Florida scrub habitat is described and both attenuation and reliability of attenuation are measured as a function of sound frequency, over several distances, speaker elevations, and microphone elevations. The spatial context of sound propagation in Florida scrub habitat is discussed and a model designed to describe contributions to overall attenuation from individual factors is presented. Sound frequencies below approximately 3.5 kHz attenuate more reliably than higher sound frequencies, suggesting that animals should pay greatest attention to relatively low sound frequencies when they assess attenuation or estimate sound-pressure level.

Animals↗
PubMed2004

Spectral-temporal factors in the identification of environmental sounds.

Three experiments tested listeners' ability to identify 70 diverse environmental sounds using limited spectral information. Experiment 1 employed low- and high-pass filtered sounds with filter cutoffs ranging from 300 to 8000 Hz. Listeners were quite good (>50% correct) at identifying the sounds even when severely filtered; for the high-pass filters, performance was never below 70%. Experiment 2 used octave-wide bandpass filtered sounds with center frequencies from 212 to 6788 Hz and found that performance with the higher bandpass filters was from 70%-80% correct, whereas with the lower filters listeners achieved 30%-50% correct. To examine the contribution of temporal factors, in experiment 3 vocoder methods were used to create event-modulated noises (EMN) which had extremely limited spectral information. About half of the 70 EMN were identifiable on the basis of the temporal patterning. Multiple regression analysis suggested that some acoustic features listeners may use to identify EMN include envelope shape, periodicity, and the consistency of temporal changes across frequency channels. Identification performance with high- and low-pass filtered environmental sounds varied in a manner similar to that of speech sounds, except that there seemed to be somewhat more information in the higher frequencies for the environmental sounds used in this experiment.

Adolescent↗
PubMed2004

Potential sound production by a deep-sea fish.

Swimbladder sonic muscles of deep-sea fishes were described over 35 years ago. Until now, no recordings of probable deep-sea fish sounds have been published. A sound likely produced by a deep-sea fish has been isolated and localized from an analysis of acoustic recordings made at the AUTEC test range in the Tongue of the Ocean, Bahamas, from four deep-sea hydrophones. This sound is typical of a fish sound in that it is pulsed and relatively low frequency (800-1000 Hz). Using time-of-arrival differences, the sound was localized to 548-696-m depth, where the bottom was 1620 m. The ability to localize this sound in real-time on the hydrophone range provides a great advantage for being able to identify the sound-producer using a remotely operated vehicle.

Air Sacs↗
PubMed2004

Measurement of an individual silver perch Bairdiella chrysoura sound pressure level in a field recording.

Simultaneous audio and video were recorded of a silver perch Bairdiella chrysoura producing its characteristic drumming sound in the field. The background noise contribution to the total sound pressure level is estimated using sounds that occurred between the pulses of the silver perch sound. This background contribution is subtracted from the total sound to give an estimate of the sound pressure level of the individual fish. A silver perch source level in the range 128-135 dB (re: 1 microPa) is obtained using an estimate of the distance between the fish and the hydrophone. The maximum distance at which an individual silver perch could be detected depends on the background sound level as well as the propagation losses. Under the conditions recorded in this study, the maximum detection distance would be 1-7 m from the hydrophone.

Air Sacs↗
PubMed2005

Sound radiation around a flying fly.

Many insects produce sounds during flight. These acoustic emissions result from the oscillation of the wings in air. To date, most studies have measured the frequency characteristics of flight sounds, leaving other acoustic characteristics--and their possible biological functions--unexplored. Here, using close-range acoustic recording, we describe both the directional radiation pattern and the detailed frequency composition of the sound produced by a tethered flying (Lucilia sericata). The flapping wings produce a sound wave consisting of a series of harmonics, the first harmonic occurring around 190 Hz. In the horizontal plane of the fly, the first harmonic shows a dipolelike amplitude distribution whereas the second harmonic shows a monopolelike radiation pattern. The first frequency component is dominant in front of the fly while the second harmonic is dominant at the sides. Sound with a broad frequency content, typical of that produced by wind, is also recorded at the back of the fly. This sound qualifies as pseudo-sound and results from the vortices generated during wing kinematics. Frequency and amplitude features may be used by flies in different behavioral contexts such as sexual communication, competitive communication, or navigation within the environment.

Acoustics↗
PubMed1996

Sound orientation behavior in cats. I. Localization of broadband noise.

Behavioral experiments measured the accuracy of the cat's voluntary head orientation responses to bursts of broadband noise at 104 locations in the frontal sound field. Cats were presented sound stimuli at randomly selected locations and received a food reward for releasing a lever when a light-emitting diode (LED) flashed at the same location. Head movements to the perceived location of the acoustic stimulus, and therefore expected location of the LED cue, were tracked by an electromagnetic sensor. Orientation responses to single sound bursts were directed to within 5 degrees of the azimuth and elevation of sounds within 15 degrees of the immediate frontal field and did not change for burst durations of 40, 100, and 200 ms. An increasing underestimation of target location was observed as the sound stimulus moved to more lateral azimuths and higher elevations. The "undershoot" phenomenon was reduced by allowing subjects to track paired stimulus bursts that repeated from the same location. These effects of sound location on the accuracy of orientation responses are predicted by the availability of mid-frequency spectral cues for sound localization.

Animals↗
PubMed1989

Relation of third and fourth heart sounds to blood velocity during left ventricular filling.

To investigate the relation between changes in left ventricular inflow velocity and the timing of third and fourth heart sounds, simultaneous phonocardiograms and continuous wave Doppler traces were recorded in 48 patients (aged 17-78) with heart disease and in 21 normal children. The onset of the first vibration of the third heart sound coincided with peak left ventricular inflow blood velocity to within 5 ms in all but two of the patients. The mean (SD) difference between the two events was 5 (5) ms, which did not differ significantly from zero. The relation was similar in patients with primary myocardial disease (11), and in those with valve disease (26), hypertension (five), and coronary artery disease (four). In the normal children, the mean interval was 2.5 (5) ms--not significantly different from zero. By contrast, the first deflection of the fourth heart sound consistently preceded the timing of peak atrial inflow velocity by 55 (10) ms. Agreement was much closer between the onset of atrial flow and the onset of the atrial sound (mean difference 1 (5) ms, not significantly different from zero). Gallop sounds seem to be closely related to changes in ventricular inflow velocity, and thus to the effects of forces acting on blood flow. The forces underlying the third sound seem to arise within the ventricle and are responsible for sudden deceleration of flow during rapid ventricular filling. The fourth sound, occurring at the onset of the "a" wave, is more likely to arise from dissipation of forces causing acceleration of blood flow--that is, atrial systole itself.

Adolescent↗
PubMed1995

Potential for lung sound monitoring during bronchial provocation testing.

BACKGROUND: The use of lung sound monitoring during bronchial provocation testing has not been clearly demonstrated. The appearance of wheeze and changes in inspiratory breath sound intensity have been analysed and related to changes in spirometric parameters and to airways hyperresponsiveness. METHODS: Lung sounds were recorded in 38 patients undergoing a routine carbachol airway challenge (CAC) test. Spirometric testing was performed before and after the inhalation of each of five cumulative doses of 320 micrograms carbachol; a fall in forced expiratory volume in one second (FEV1) by 20% or more was considered as significant. Lung sound analysis was carried out using a computerised system. RESULTS: The CAC test was positive (CAC+) in 21 patients and negative (CAC-) in 17. At the final stage of the challenge, wheeze was identified in 10 positive patients (48%) and in one negative patient (6%); in non-wheezers the inspiratory breath sound intensity decreased significantly from baseline in 11 CAC+ patients (mean (SD) change -35 (24%)) but not in 16 CAC- patients (mean (SD) change 5 (24%)). In all non-wheezers a linear relationship was found between breath sound intensity and the squared inspiratory airflow (r = 0.53-0.92) which became looser after the inhalation of carbachol. CONCLUSION: When unertaking bronchial provocation testing the accurate identification of wheeze may prove useful in avoiding or shortening the test because of the presumed relationship between wheeze and airways hyperresponsiveness. Changes in breath sound intensity may also be useful, but further studies are required to define the threshold for significant changes in this index.

Adult↗
PubMed2006

Sound localization under perturbed binaural hearing.

This paper reports on the acute effects of a monaural plug on directional hearing in the horizontal (azimuth) and vertical (elevation) planes of human listeners. Sound localization behavior was tested with rapid head-orienting responses toward brief high-pass filtered (>3 kHz; HP) and broadband (0.5-20 kHz; BB) noises, with sound levels between 30 and 60 dB, A-weighted (dBA). To deny listeners any consistent azimuth-related head-shadow cues, stimuli were randomly interleaved. A plug immediately degraded azimuth performance, as evidenced by a sound level-dependent shift ("bias") of responses contralateral to the plug, and a level-dependent change in the slope of the stimulus-response relation ("gain"). Although the azimuth bias and gain were highly correlated, they could not be predicted from the plug's acoustic attenuation. Interestingly, listeners performed best for low-intensity stimuli at their normal-hearing side. These data demonstrate that listeners rely on monaural spectral cues for sound-source azimuth localization as soon as the binaural difference cues break down. Also the elevation response components were affected by the plug: elevation gain depended on both stimulus azimuth and on sound level and, as for azimuth, localization was best for low-intensity stimuli at the hearing side. Our results show that the neural computation of elevation incorporates a binaural weighting process that relies on the perceived, rather than the actual, sound-source azimuth. It is our conjecture that sound localization ensues from a weighting of all acoustic cues for both azimuth and elevation, in which the weights may be partially determined, and rapidly updated, by the reliability of the particular cue.

Acoustic Stimulation↗
PubMed1992

Midline and lateral field sound localization in the ferret (Mustela putorius): contribution of the superior olivary complex.

1. The ability of ferrets to localize sound in space was determined before and after unilateral or bilateral lesions of the superior olivary complex (SOC). Lesions were made by pressure injection of kainic acid into the SOC through a stereotaxically positioned glass micropipette. The lesions destroyed the cell bodies in the superior olive without disrupting fibers of passage in the trapezoid body or other pathways in the auditory brain stem. The integrity of fibers was demonstrated by protargol staining of axonal processes and by the retrograde transport of horseradish peroxidase (HRP) from the inferior colliculus to other auditory brain stem nuclei. Behavioral tests were carried out separately for sound localization at midline and lateral field positions. Minimum audible angles were determined for single 45-ms noise bursts presented through paired loudspeakers positioned symmetrically around 0, -60, and +60 degrees azimuth. 2. Four ferrets received complete lesions of the left SOC, and two received complete lesions of the right SOC. In general, unilateral destruction of the superior olive resulted in impairments in sound localization in both left and right lateral fields. In some cases, deficits were also apparent on midline. Four additional animals received unilateral lesions that spared cells within the SOC. In most cases, deficits were apparent despite incomplete lesions of the SOC. The pattern of deficits was generally consistent with that found in animals with complete lesions. Most animals had difficulty localizing sounds in the lateral fields. 3. Four animals received bilateral lesions of the SOC. Three had complete or near-complete destruction of the superior olive on one side of the brain with relatively minor damage on the other side. Each of these animals exhibited behavioral deficits that were particularly severe ipsilateral to the more extensively damaged superior olive. One animal with complete bilateral destruction of the SOC was incapable of sound localization, even with 2-s noise bursts. This animal, however, suffered severe motor impairments after surgery that might have contributed to the apparent inability to localize sound. 4. Two animals with kainic acid lesions that caused little or no damage to the SOC were still capable of high levels of performance in tests of sound localization and had no elevation in minimum audible angles. These cases served as controls for the possible effects of nonspecific brain damage and demonstrated that kainic acid injections per se resulted in no obvious deficits in our test situation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2003

Use of sound-absorbing panel to reduce noisy incubator reverberating effects.

OBJECTIVES: To assess the amplification and distortion of noise in incubators by measuring noise levels from various sources under various conditions. STUDY DESIGN: We recorded sound pressure levels (SPL) of background noise, baby crying, alarms and porthole closing with the incubator hood open or closed. Then we tried to reduce the sound level in the incubator by applying a sound absorbing panel to the ceiling of the hood. RESULTS: The sound sources analysed produced very high SPL. In free field baby crying and porthole noise were, respectively, 81-83 dB and 70-71 dB, closing the hood they raised to 84-87 and 73-74 dB: this means that the noise perceived by a baby in the incubator had twice the SPL of the same noise emitted in a free field; alarm noise was 56-57 dB inside incubators. Sound emitted inside the hood was also distorted, i.e. it had different features from the same source in a free field. The insulating panel prevented amplification and distortion due to the hood and reduced the SPL of alarms. Only background noise did not decrease with the panel. Sound absorbing panel reduced baby's crying, porthole noise and alarm noise SPL to 82-85, 70-71 and 50-51 dB, respectively. CONCLUSIONS: Incubators are reverberating environments, which amplify the baby's cry and other noises produced inside the hood. The frequency components of noises are altered by the hood. The sound absorbing panel reduced this phenomenon.

Crying↗
PubMed2006

Aerodynamic and sound intensity measurements in tracheoesophageal voice.

BACKGROUND: In laryngectomized patients, tracheoesophageal voice generally provides a better voice quality than esophageal voice. Understanding the aerodynamics of voice production in patients with a voice prosthesis is important for optimizing prosthetic designs and successful voice rehabilitation. OBJECTIVES: To measure the aerodynamics and sound intensity in tracheoesophageal voice production. STUDY DESIGN AND METHODS: We built a special setup, which consisted of a Pentium 200 MHz computer with an AD-DA interface card and Labview 4.01 software. In an oral/nasal mask we constructed several mass flow sensors and a microphone. This measured both the oral airflow and the level of sound. For the measurement of endotracheal pressure, which is the driving force behind the airflow, we used a transducer which was connected to the tracheostoma. The endoesophageal pressure was measured at the level of the prosthesis in the esophagus by a Mikrotip transducer. Using this we could determine how much the voice prosthesis contributes to the overall pressure drop of the phonatory tract. Furthermore, the average airflow rate as a function of the sound pressure levels could be determined. RESULTS: In our population, 6 out of 7 patients showed a positive relationship between trans-source airflow and generated sound intensity. We compared our prosthesis pressure drop values with in vitro data and found that there are some differences, possibly due to difference in age of the prosthesis and physiological circumstances in vivo. The overall contribution of the voice prosthesis to the airway resistance depends on the level of phonation and the type of device. In our patient group it is apparent that the pharyngoesophageal (PE) segment has the greatest share of the total pressure drop, especially at higher airflow rates. We measured a 27% pressure drop in airflow over the voice prosthesis. Different tracheostoma occlusion methods did not have any effect on the aerodynamics and sound intensity. One patient that had had a jejunal graft for reconstruction showed, not unexpectedly, extremely different aerodynamic values. We were unable to define optimal airflow rates or optimal resistance values for sound production in the PE segment. CONCLUSION: The aerodynamic characteristics of voice production in laryngectomized patients with voice prostheses are determined by both prosthetic factors and PE segment tissue factors. In our patient group the PE segment is responsible for the greatest pressure drop. We found no significant difference in pressure drop and sound intensity for different tracheostoma occlusion methods.

Aged↗
PubMed1981

Lung sounds in patients with emphysema.

We recorded an index of breath sound intensity (Ib) and the transmission of white noise (Tn) over four lung regions between apex and base in eight subjects with emphysema. The Ib and Tn were recorded over the whole range of lung volume from residual volume to total lung capacity. Each value was expressed as a fraction of the value recorded over the apical region with the help of an analog divider. The ratio of Ib to Tn was computed to correct for differences in Ib due to differences in transmission of sound. The ratio of Ib and Tn was computed to correct for differences in Ib due to differences in transmission of sound. The ratio of Ib to Tn was also expressed as a fraction of the value recorded over the apex. Both Ib and Tn had definite patterns in subjects with emphysema but varied considerably from breath to breath. The Ib and Tn were more reproducible in normal subjects. The magnitude and the sequence of Ib, Tn, and Ib/Tn were also different in subjects with emphysema and normal subjects. The ratio of Ib to Tn is an index of sound production in both normal subjects and subjects with emphysema. We conclude that both production and transmission of breath sounds vary from breath to breath in patients with emphysema. There are areas of both increased and decreased production and transmission of sound. If regional breath sound production (Ib/Tn) is related to regional ventilation in persons with emphysema as in normal subjects, these findings further suggest that regional ventilation varies from breath to breath and is also altered drastically from the normal pattern, leading to a severe ventilation and perfusion inequality so characteristic of emphysematous lungs.

Female↗
PubMed1981

First heart sound in atrial septal defect.

This is a retrospective study of 25 patients with secundum-type of ASD, confirmed by catheterization and angiocardiography. As controls, 25 normal subjects of matching age were studied. The phonocardiograms and carotid pulses of the 2 groups were recorded and compared. Special attention was paid to the interval between the 2 main components (Ia and Ib) of the first heart sound, to the amplitude of both Ia and Ib, and to the relationship between carotid upstroke and first heart sound. All intervals between sound components of the patients with ASD were found similar to those of the controls. No increase in amplitude of Ib could be documented. The amplitude of the first heart sound relative to that of the second sound (measured from the ratio I/IIA) was similar to that of the controls, Finally, a slight precedence of aortic valve opening (obtained from the carotid upstroke time minus transmission time) over the second component of the first sound (Ib) was found both in ASD and in controls. In view of these facts, a tricuspid contribution to the mechanism of the b component of the first heart sound appears highly unlikely. On the other hand, this component seems closely related to the dynamic events (blood acceleration and walls deceleration in the aortic root) that follow the aortic valve opening.

Adolescent↗