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At least 1,243 records · Page 69Linked to original sources
PubMed1999

Sound exposure as a measure against driver drowsiness.

Twelve lorry drivers participated in a field study, including in total 110 tests of a waking sound system. The system was based on a time and frequency varied sound, generated at intervals between 1 and 15 min for periods of 3-7 s. The waking effect of the sound was analysed through subjective ratings. Exposure to the sounds was correlated to improvements of the immediate as well as the long-term self-reported changes in wakefulness. The results of the study show consistently positive assessments concerning the applied waking system, both regarding the system as a measure for raised wakefulness, increased road safety and the interest in having the system installed in the vehicle. The waking sounds were in no case felt to be annoying. Analyses of the wakefulness and other factors and the interaction related to fatigue and driving are included in the investigation.

Accidents, Traffic↗
PubMed2004

Irrelevant sound disrupts speech production: exploring the relationship between short-term memory and experimentally induced slips of the tongue.

To explore the relationship between short-term memory and speech production, we developed a speech error induction technique. The technique, which was adapted from a Japanese word game, exposed participants to an auditory distractor word immediately before the utterance of a target word. In Experiment 1, the distractor words that were phonologically similar to the target word led to a greater number of errors in speaking the target than did the dissimilar distractor words. Furthermore, the speech error scores were significantly correlated with memory span scores. In Experiment 2, memory span scores were again correlated with the rate of the speech errors that were induced from the task-irrelevant speech sounds. Experiment 3 showed a strong irrelevant-sound effect in the serial recall of nonwords. The magnitude of the irrelevant-sound effects was not affected by phonological similarity between the to-be-remembered nonwords and the irrelevant-sound materials. Analysis of recall errors in Experiment 3 also suggested that there were no essential differences in recall error patterns between the dissimilar and similar irrelevant-sound conditions. We proposed two different underlying mechanisms in immediate memory, one operating via the phonological short-term memory store and the other via the processes underpinning speech production.

Acoustic Stimulation↗
PubMed2004

Children with obstructive sleep-disordered breathing generate high-frequency inspiratory sounds during sleep.

STUDY OBJECTIVES: We observed that some children with adenotonsillar hypertrophy and obstructive sleep-disordered breathing (SDB) make high-frequency inspiratory sounds (HFIS) during sleep. Our objective was to determine whether HFIS occur in most children with obstructive SDB and adenotonsillar hypertrophy and whether adenotonsillectomy reduces HFIS. DESIGN: Prospective consecutive-entry trial. SETTING: Sleep laboratory. PARTICIPANTS: Twenty-six children between 6 and 12 years of age with adenotonsillar hypertrophy suspected of having obstructive SDB. MEASUREMENTS AND RESULTS: We performed polysomnography and measured sounds during sleep with a microphone suspended above the bed. Sounds were recorded on a computer at 44 kHz, analyzed with fast Fourier transformation for frequency content. HFIS were sounds occurring during an inspiration with frequencies greater than 2 kHz. HFIS were different from the low-frequency (< 2 kHz) sounds described in snoring adults. HFIS usually occurred in consecutive breaths, occasionally exceeding 100. We counted the number of HFIS that occurred per hour of sleep. Children who made more HFIS had more obstructive SDB than did those who did not make the HFIS, and there was a significant positive correlation between the number of HFIS and the obstructive apnea-hypopnea index. Children with more than 3 apneas and hypopneas per hour of sleep all made at least 10 HFIS per hour, and all children who had more than 10 HFIS per hour had obstructive apnea-hypopnea index values greater than 1. Children with adenotonsillar hypertrophy made more HFIS than did those children whose tonsils and adenoids had been removed. CONCLUSIONS: HFIS may be a marker of disturbed breathing during sleep in children with adenotonsillar hypertrophy.

Adenoidectomy↗
PubMed1998

Optical recording of responses to frequency-modulated sounds in the auditory cortex.

Using an optical recording method with a voltage-sensitive dye, we recorded activities in the primary auditory cortex (AI) of anesthetized guinea pigs in response to frequency-modulated (FM) sounds and sounds with stepwise changes in frequency (SF). Responses to the FM sound showed a spatiotemporal pattern in which a localized active spot traversed the isofrequency bands in the AI, and they differed from the band-like responses to the SF sound. These results indicate that time-varying sounds are represented as spatiotemporal activation of tonotopic organization in the AI by spectral cues with interactions between frequency bands.

Acoustic Stimulation↗
PubMed2003

Plastic cortical changes induced by learning to communicate with non-speech sounds.

With Morse code, an acoustic message is transmitted using combinations of tone patterns rather than the spectrally and temporally complex speech sounds that constitute the spoken language. Using MEG recordings of the mismatch negativity (MMN, an index of permanent auditory cortical representations of native language speech sounds), we probed the dominant hemisphere for the developing Morse code representations in adult Morse code learners. Initially, the MMN to the Morse coded syllables was, on average, stronger in the hemisphere opposite to the one dominant for the MMN to native language speech sounds. After a training period of 3 months, the pattern reversed, however: the mean Morse code MMN became lateralized to the hemisphere that was predominant for the speech-sound MMN. This suggests that memory traces for the Morse coded acoustic language units develop within the hemisphere that already accommodates the permanent traces for natural speech sounds. These plastic changes manifest, presumably, the close associations formed between the neural representations of the tone patterns and phonemes.

Acoustic Stimulation↗
PubMed1992

A comparison of sound quality judgments for monaural and binaural hearing aid processed stimuli.

Fifteen adults with bilaterally symmetrical mild and/or moderate sensorineural hearing loss completed a paired-comparison task designed to elicit sound quality preference judgments for monaural/binaural hearing aid processed signals. Three stimuli (speech-in-quiet, speech-in-noise, and music) were recorded separately in three listening environments (audiometric test booth, living room, and a music/lecture hall) through hearing aids placed on a Knowles Electronics Manikin for Acoustics Research. Judgments were made on eight separate sound quality dimensions (brightness, clarity, fullness, loudness, nearness, overall impression, smoothness, and spaciousness) for each of the three stimuli in three listening environments. Results revealed a distinct binaural preference for all eight sound quality dimensions independent of listening environment. Binaural preferences were strongest for overall impression, fullness, and spaciousness. Stimulus type effect was significant only for fullness and spaciousness, where binaural preferences were strongest for speech-in-quiet. After binaural preference data were obtained, subjects ranked each sound quality dimension with respect to its importance for binaural listening relative to monaural. Clarity was ranked highest in importance and brightness was ranked least important. The key to demonstration of improved binaural hearing aid sound quality may be the use of a paired-comparison format.

Acoustics↗
PubMed1992

The psychophysics of concurrent sound segregation.

To perceptually separate concurrent complex sounds, normally hearing listeners simultaneously combine information across a wide range of frequency components. Three psychoacoustical experiments are described which investigate different forms of this across-frequency processing. The first two experiments investigate the role of coherence of frequency modulation (FM) between widely separated frequency components of a complex sound. The first experiment bolsters existing evidence that, for harmonic sounds, listeners can discriminate coherent from incoherent FM, but only by detecting the mistuning that arises from incoherent FM. The second demonstrates that, for inharmonic sounds, coherence of FM has no effect on the phenomenon of modulation detection interference (see Moore & Shailer, this symposium) once within-channel cues (combination tones and beating) are masked by background noise. It is concluded that there is not an across-frequency mechanism specific to the detection of FM incoherence. The third experiment investigates the extent to which the detection of mistuning of one component of a harmonic complex is impaired by an interfering sound (the 'interferer') with a frequency spectrum similar to that of the mistuned component. When the interferer is gated on and off with the harmonic complex, it has only a small effect provided that its level is more than 3 dB below that of the target. However, when the interferer starts before and ends after the complex, thresholds are elevated more, and this elevation occurs even for low-level interferers. Explanations of this effect in terms of adaptation and of auditory streaming are discussed.

Acoustic Stimulation↗
PubMed2004

Effect of intracrystalline water on longitudinal sound velocity in tetragonal hen-egg-white lysozyme crystals.

Longitudinal sound velocity of tetragonal hen-egg-white (HEW) lysozyme crystals was measured during air drying by ultrasonic pulseecho method. The sound velocity increases with exposure to open air and approaches a constant value. The maximum value is approximately 2900 m/s that is about 1.6 times as much as that of original one before drying. In addition, the sound velocity clearly recovers to original one after immersing the dried crystal in solution. Therefore, the sound velocity in tetragonal HEW lysozyme crystals can be reversibly changed due to dehydration and rehydration. These changes in sound velocity are discussed in the light of water-mediated intramolecular and intermolecular interactions in the crystals.

Animals↗
PubMed2006

Unintelligible low-frequency sound enhances simulated cochlear-implant speech recognition in noise.

Speech can be recognized by multiple acoustic cues in both frequency and time domains. These acoustic cues are often thought to be redundant. One example is the low-frequency sound component below 300 Hz, which is not even transmitted by the majority of communication devices including telephones. Here, we showed that this low-frequency sound component, although unintelligible when presented alone, could improve the functional signal-to-noise ratio (SNR) by 10-15 dB for speech recognition in noise when presented in combination with a cochlear-implant simulation. A similar low-frequency enhancement effect could be obtained by presenting the low-frequency sound component to one ear and the cochlear-implant simulation to the other ear. However, a high-frequency sound could not produce a similar speech enhancement in noise. We argue that this low-frequency enhancement effect cannot be due to linear addition of intelligibility between low- and high-frequency components or an increase in the physical SNR. We suggest a brain-based mechanism that uses the voice pitch cue in the low-frequency sound to first segregate the target voice from the competing voice and then to group appropriate temporal envelope cues in the target voice for robust speech recognition under realistic listening situations.

Acoustic Stimulation↗
PubMed2005

Aberration correction by nonlinear beam mixing: generation of a pseudo point sound source.

Nonlinear beam mixing with microbubbles was explored to create a pseudo point source for aberration correction of therapeutic ultrasound. A damping coefficient for a bubble driven by a dual frequency sound field was derived by revisiting Prosperetti's linearized damping model. As a result, the overall damping term for dual frequency was obtained by linear summation of two damping terms for each frequency. The numerical simulation based on the bubble model suggests that the most efficient size range to generate a 1 MHz frequency from 4 MHz and 5 MHz sound sources is 2.6 to 3.0 microm. Furthermore, this size range constitutes the primary distribution of a specific ultrasound contrast agent. When a chamber of 0.1% of the diluted agent is sonified by 4 MHz and 5 MHz sound beams with 80 degrees incident angle between them, an approximately 100 Pa, 1 MHz difference frequency signal can be measured approximately 10 cm away. In addition, the received 1 MHz difference frequency signal shows omni-directional characteristics, even though the overlap zone of the two sound beams is on the order of the difference frequency wavelength. Therefore, the induced sound source can be considered as a pseudo point source and is expected to be useful for aberration correction for therapeutic ultrasound.

Animals↗
PubMed1996

Audible in utero sound caused by the ultrasonic radiation force from a real-time scanner.

While investigating in utero sound levels during vibro-acoustic stimulation on the maternal abdomen it was noticed that noise level increased when the real-time ultrasonic scanner beam was directed at the sensing hydrophone. The noise was recorded and later analysed for frequency content and waveform. It appeared related to the scanning and frame rate frequencies of the scanner used. Sounds may originate from radiation pressure produced when the ultrasound beam is absorbed by tissue or reflected from bone or the metal hydrophone. This implies that although ultrasound cannot be heard per se, any modulation of its intensity will produce vibrations in the maternal tissues or reflecting structures such as skull bone, and especially stapes, malleus and incus, that would be heard as sound by the fetus. The intensity of the sound produced varied with orientation of the transducer beam and this may itself produce a stimulation. Based on our recordings (Fig. 1), it was calculated (please see Appendix) that the fetus would hear a sound corresponding to 84dB noise pressure level in air.

Acoustic Stimulation↗
PubMed1996

Processing of complex sounds in the human auditory cortex as revealed by magnetic brain responses.

Processing of simple and complex sounds in the human brain was compared by recording extracranial magnetic mismatch responses (MMNm; the magnetic counterpart of the mismatch negativity, or MMN) to frequency changes in these sounds. Generator sources, modeled as equivalent current dipoles (ECDs), of MMNm responses to a change in one frequency element of complex sounds (a chord and a serial tone pattern) were located in supratemporal auditory cortex, on average, 10 mm medially to the source of an MMNm elicited by an identical frequency change in a simple tone. These results suggest that at least partially different supratemporal neuron populations are involved in processing changes in simple and complex sounds and that sensory-memory representations for these sounds may be located in different fields of the auditory cortex.

Adult↗
PubMed2004

Development of an electro-stethoscope system and design of an optimum filter based on tissue sound transmission for noninvasive early diagnosis of malfunction of an implanted mechanical total artificial heart.

Early diagnosis of the malfunction of a mechanical artificial heart implanted in a patient who has been discharged from hospital is very important. We have developed an electro-stethoscope system that enables the malfunction of an artificial heart to be detected from the analysis of sound signals from the artificial heart. The sound data can be transmitted to a hospital via a mobile telephone or the Internet, so that doctors can examine the condition of the artificial heart. The optimum frequency characteristics of a low-pass filter for the elimination of ambient sound through the electro-stethoscope casing were obtained by simulating sound transmission through tissue. We evaluated the usefulness of the electro-stethoscope system using a goat in which an undulation pump total artificial heart had been implanted. A frequency analysis of the sound signal provided information on the degree of degradation of each mechanical component of the artificial heart. The results of this study showed that the electro-stethoscope system is useful for the early detection of the malfunction of an artificial heart at home, and that the use of the system contributes to improvement in the quality of life of patients.

Animals↗
PubMed1995

Autofluorescence of bulk sound and in vitro demineralized human root dentin.

The aim of this paper is to report on the demineralization-induced changes in dentin autofluorescence. Confocal laser scanning microscopy (CLSM) images and fluorescence excitation and emission spectra in vitro demineralized root surfaces and sound controls on the same tooth roots were compared. When observed in CLSM images, demineralized dentin, excited at 488 nm, gave an increased emission at 529 nm compared to sound dentin. The difference in fluorescence decreased deeper into the root, as the sound dentin underneath the lesion was reached. In contrast, when using fluorescence spectrophotometry, excitation around 460 and 488 nm yielded a lower emission around 520 nm for demineralized dentin than for sound dentin, but in a more pronounced peak. From excitation spectra for emission around 520 nm, it could be seen that in demineralized dentin the contribution of excitation between 480 and 520 nm was more important than in sound dentin. The recorded fluorescence in CLSM images was not affected by demineralization-caused changes in scattering and absorption properties, due to the small measurement volume. Thus, the increased fluorescence for demineralized dentin implies an increased quantum yield. In fluorescence spectrophotometry, where the measurement volume is large, changes in scattering and absorption do have an influence on the fluorescence signal. Then, increased absorption by non-fluorescing chromophores and increased re-absorption around the emission wavelength may compensate for the increase in quantum yield and absorption around the excitation wavelength by fluorophores.

Absorption↗
PubMed1992

Mobility and percussion sound of healthy upper incisors and canines.

In order to evaluate the correlation between mobility and percussion sound, 126 upper incisors and canines in 21 student volunteers were measured by means of the Periotest (Siemens), by evaluating the percussion sound subjectively and by analyzing its spectrum. The attenuation time and frequency of the sound were measured for each tooth. A logical mobility and percussion sound existed in accordance with the sizes of the teeth. Spearman correlation coefficients close to 1.00 were noted in individual cases between the Periotest and the three other tests describing the percussion sounds.

Adult↗
PubMed2001

Musical sound processing in the human brain. Evidence from electric and magnetic recordings.

Recently, our knowledge regarding the brain's ability to represent invariant features of musical information even during the performance of a simultaneous task (unrelated to the sounds) has accumulated rapidly. Recordings of the change-specific mismatch negativity component of event-related brain potentials have shown that temporally and spectrally complex sounds as well as their relations are automatically processed by human auditory cortex. Furthermore, recent magnetoencephalographic and positron emission topographic investigations indicate that this processing differs between phonetic and musical sounds within and between the cerebral hemispheres. These data thus suggest that despite the focus of listeners' conscious attention, relatively complex sound phenomena can be encoded by neural mechanisms that are specialized for musical sounds.

Auditory Perception↗
PubMedDate not supplied

Temperature corrected speed of sound for use in soft tissue imaging.

It has recently been suggested that values for the speed of sound in tissues currently reported in the literature are higher than those presently in use in diagnostic ultrasound. The purpose of this note is to indicate that the newer data under criticism was obtained at body temperature (and higher), whereas speed of sound in tissue data currently in use by medical physicists appear to be based on measurements made at room temperature. If a positive ultrasound temperature coefficient for soft tissue is used to extrapolate the data from body to room temperature, it can be seen that the extrapolation falls within the region of the bulk of room temperature measurements. Fortunately, most applications in which speed of sound data in tissue is used involves partial paths through lipidous tissue. Since the speed of sound in lipidous tissue is relatively lower at body temperature (liquid has a negative temperature coefficient) than is the speed of sound in soft tissue, the mean speed is lower than that obtained in soft tissue alone and room temperature values are probably justified. However, medical physicists should be careful to use body temperature data for soft tissue when the insonified region is composed mainly of soft tissue.

Animals↗
PubMed2000

European methodology for testing the airborne sound insulation characteristics of noise barriers in situ: experimental verification and comparison with laboratory data

In the frame of the 1994-1997 Standard, Measurement and Testing program, the European Commission funded a research project, named Adrienne, to define new test methods for measuring the intrinsic characteristics of road traffic noise reducing devices in situ. The research team produced innovative methods for testing the sound reflection/absorption and the airborne sound insulation characteristics of noise barriers. These methods are now under consideration at CEN (European Committee for Standardization), to become European standards. The present work reports a detailed verification of the test method for airborne sound insulation over a selection of 17 noise barriers, representative of the Italian and European production. The samples were tested both outdoors, using the new Adrienne method, and in laboratory, following the European standard EN 1793-2. In both cases the single number rating for airborne sound insulation recommended by the European standard was calculated. The new method proved to be easy to use and reliable for all kinds of barriers. It has been found sensitive to quality of mounting, presence of seals, and other details typical of outdoor installations. The comparison between field and laboratory results shows a good correlation, while existing differences can be explained with the different sound fields and mounting conditions between the outdoor and laboratory tests. It is concluded that the Adrienne method is adequate for its intended use.

Journal Article↗