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At least 19 recordsLinked to original sources
PubMed1992

[Interaction between acoustic environment and landscape--the effect of acoustic environment on perceived landscape and the effect of landscape on perceived acoustic environment].

The effect of acoustic environment on the impression of the landscape and the effect of the landscape on the impression of the acoustic environment were investigated by a multivariate technique using a semantic differential method. The resulting five dimensions were interpreted as "Calmness", "Activity", "Naturalness", "Uniqueness", and "Volume (Magnitude)" for both landscape and sound evaluations. These common psychological qualities are considered to be the intermodalities of visual and auditory processing. Further, the consonance phenomenon through the intermodalities, a kind of interaction between auditory and visual processing which changes the psychological qualities to the same direction, was observed when the combination of the acoustic environment and landscape was evaluated to be matched. These results may be the basis of the soundscape design under various kinds of landscape.

Auditory Perception↗
PubMed1996

Laser acoustic emission thermal technique (LAETT): a technique for generating acoustic emission in dental composites.

OBJECTIVES: This study was designed to investigate a new method for generating interfacial debonding between the resin matrix and filler particles of dental composites. METHODS: A pilot study was conducted to evaluate laser-induced acoustic emission in dental resins filled with varying quantities of particles. Model systems of 50/50 BisGMA/TEGDMA resin reinforced with 0, 25, and 75 wt% 5-10 micrometers silanated BaSiO(6) were analyzed. The sample size was 3.5 mm diameter x 0.25-0.28 mm thick. A continuous wave CO2 laser (Synrad Infrared Gas Laser Model 48-1) was used to heat the composite samples. Acoustic events were detected, recorded and processed by a model 4610 Smart Acoustic Monitor (SAM) with a 1220A preamp (Physical Acoustic Corp.) as a function of laser power. RESULTS: Initially, the acoustic signal from the model composites produced a burst pattern characteristic of fracturing, about 3.7 watts laser power. Acoustic emission increased with laser power up to about 6 watts. At laser powers above 6 watts, the acoustic emission remained constant. The amount of acoustic emission followed the trend: unfilled resin > composite with 25 wt% BaSiO(6) > composite with 75 wt% BaSiO(6). SIGNIFICANCE: Acoustic emission generated by laser thermal heating is dependent on the weight percent of filler particles in the composite and the amount of laser power. For this reason, laser thermal acoustic emission might be useful as a nondestructive form of analysis of dental composites.

Analysis of Variance↗
PubMed1999

A comparison of three methods for the diagnosis of sound, stained, and carious dentine: conventional, mechanico-acoustic, and laser-acoustic methods.

OBJECTIVE: The authors examined two novel and objective methods for diagnosing stained, carious, and sound dentine, a mechanico-acoustic method and a laser-acoustic method, and compared these with the conventional but subjective method of visual and tactile assessment using a dental probe. SUMMARY BACKGROUND DATA: It is accepted clinical practice to leave stained but relatively firm dentine on the pulpal surface of dental cavities prepared for restoration. The problem for the clinician is in deciding which dentine is carious and which is stained but acceptable to be left in situ. There is no objective method for making this decision, it is usually made on the basis of visual examination and tactile assessment using a dental probe. METHODS: The authors used Fourier analysis of acoustic waves arising from mechanical (dental probe) or laser (Er:YAG laser) interaction with the tooth surface and compared the results with the subjective assessment of the same tissue surfaces as judged by a clinician using visual and tactile assessment with the same dental probe. RESULTS: The results showed that both the mechanico-acoustic and laser-acoustic methods were more accurate and more objective than the conventional visual/tactile method and that an analysis of both the integral and spectral signals produced by the Er:Yag Laser (lambda = 2.94 microns) allowed for a more accurate diagnosis than the other two methods examined. CONCLUSIONS: Both mechanico-acoustic and laser-acoustic methods of diagnosing sound, stained, and carious dentine were more accurate than the subjective visual/tactile method using a dental probe. The laser-acoustic method was the most accurate of all of the methods compared. An advantage of the laser-acoustic method is that it could be included into the actual process of cavity preparation when using an Er:YAG laser, providing an objective and more accurate assessment of the nature of the remaining dentin and may therefore be more economic of time, eliminating the necessity for constant cessation of drilling to assess the nature of the target tissue.

Acoustics↗
PubMed2003

[Indices of fast acoustic adaptation in unilateral recording of short latent acoustic potentials in people with normal hearing and chronic functional voice disturbances].

The authors presented the results of the study of the central parts of the acoustic analyzer using the method of recording the short latent acoustic evoked potentials (SAEP), with stimulus frequency of 21.1 and 90 Hz, in the persons suffered from chronic functional voice disturbances (CFVD). A total of 67 persons aged from 23 to 45 years with normal hearing function were examined; among them, the normal voice forming and the acoustic apparatus were found in 38, and CFVD was detected in 29 persons. The state of the central parts of the acoustic analyzer examined by using a method of fast acoustic adaptation (FAA) during recording the SAEP points to the interrelation between the acoustic and vocal systems on the level of brainstem. It should be mentioned that investigating the brainstem responses to auditory stimuli, especially of different frequency, is helpful to reveal the preclinical disturbances in the functional state of the central nervous system, and brainstem structures of the acoustic analyzer, in particular. So, it contributes to early diagnosis of these affections in the persons with voice and hearing pathology. The study of the central mechanisms of the interrelations between the acoustic and voice forming systems contributes to new progressive achievements in phonoaudiology and elaboration of new approaches in diagnosis and treating the voice and acoustic disturbances, which remain one of the burning problems in present otorhinolaryngology.

Acoustic Stimulation↗
PubMed1997

The magnitude of random errors in acoustic rhinometry and re-interpretation of the acoustic profile.

By measuring the effect of incomplete acoustic seal and increasing nosepiece insertion depth on the derived nasal acoustic profile, this study quantifies the random errors that may arise in the course of the clinical practice of acoustic rhinometry using the insert nosepiece. The relative movement of the nose and nosepiece also enables us to separate the contribution of each to the acoustic curve. Sixteen volunteers were tested using a commercial rhinometer. As a consequence of this study we are able to formulate the following conclusions: (1) The first minimum of the nasal acoustic profile is due to the end of the nosepiece, but may be further diminished by the position of the nosepiece tip on or within the nose. (2) The second minimum is due to the nasal valve, to which the head of the inferior turbinate contributes. (3) Acoustic rhinometry is extremely sensitive to acoustic leaks and results obtained without a fluid acoustic sealant cannot be considered valid. (4) The errors associated with the nosepiece insertion technique are very small unless the nosepiece is forced into the nasal vestibule.

Acoustics↗
PubMedDate not supplied

Pressure-induced modifications of the acoustic nerve. Part I: The acoustic reflex.

It is commonly thought that as an acoustic neuroma grows it exerts pressure on the acoustic nerve resulting in alterations of the acoustic reflex and brain stem audiometry. This hypothesis has not been confirmed. In this study in an animal model, acute pressure was applied to the nerves of the internal auditory canal, and changes in the acoustic reflex were measured. Our results support the theory that pressure on the acoustic nerve causes an increase in the rate of adaptation and a decrease in the amplitude of the acoustic reflex. The contralateral reflex appears to be the most sensitive indicator of these effects. We feel that this animal model can be useful to investigate the effects of pressure on the acoustic nerve.

Acoustic Impedance Tests↗
PubMed2001

Quantum mechanical representation of acoustic streaming and acoustic radiation pressure.

We discuss acoustic streaming and acoustic radiation pressure from the viewpoint of energy and momentum of acoustic waves, using a quantum mechanical representation of acoustic waves. We represent the energy epsilon and momentum mu of acoustic waves as epsilon=n(p)homega and mu=n(p)hk; here n(p) is the phonon density, omega is the frequency, k is the wave number, and h is Planck's constant. It is easy to derive the momentum of acoustic waves as mu=epsilon/c (c is the sound velocity). Therefore, we can represent the acoustic streaming and acoustic radiation pressure in terms of the momentum.

Journal Article↗
PubMed2000

Active control of harmonic sound transmission into an acoustic enclosure using both structural and acoustic actuators

This paper describes an analytical and experimental investigation into the active control of harmonic sound transmission in a structural-acoustic coupled system. A rectangular enclosure is considered that has five acoustically rigid walls and a flexible plate on the remaining side through which a harmonic sound wave is transmitted into the enclosure. The control system is designed to globally reduce the sound field inside the enclosure, and the roles of structural and acoustic actuators are of particular interest. Three control configurations, classified by the type of actuators, are compared and discussed. They are: (i) use of a single point-force actuator, (ii) use of a single acoustic piston source, and (iii) simultaneous use of both a point-force actuator and an acoustic piston source. It is shown both analytically and experimentally that the point-force actuator is effective in controlling plate-dominated modes while the acoustic source is effective in controlling cavity-dominated modes. Since the transmitted sound field is governed by both plate- and cavity-dominated modes, the hybrid use of both types of actuators is shown to be a desirable configuration for the active control of sound transmission into a structural-acoustic coupled system.

Journal Article↗
PubMed1991

Changes in EEG power, acoustic evoked potentials and heart rate after mildly arousing non-acoustic priming stimuli in carp (Cyprinus carpio).

1. Changes in EEG power spectrum of carp to a priming non-acoustic stimulus followed by acoustic clicks were compared to those due to acoustic clicks delivered alone. Recordings were made from the telencephalon, midbrain and medulla. Acoustic evoked potentials (AEPs) to the clicks were also recorded. 2. EEG power changes to non-acoustic stimuli occurred over the whole 1-40 Hz frequency range and were regionally specific and consistent. 3. The changes in the EEG midfrequency 12-24 Hz power spectrum to non-acoustic stimuli were significantly correlated with changes in the AEP to subsequent clicks. An elevated medullary AEP amplitude and reduced duration were correlated with increased medullary EEG power and increased midbrain AEP duration. 4. Telencephalic EEG power changes were inversely related to changes in medullary and midbrain AEP amplitude.

Acoustic Stimulation↗
PubMed1996

Dose and diameter relationships for facial, trigeminal, and acoustic neuropathies following acoustic neuroma radiosurgery.

PURPOSE AND OBJECTIVE: To define the relationships between dose and tumor diameter for the risks of developing trigeminal, facial, and acoustic neuropathies after acoustic neuroma radiosurgery, a large single-institution experience was analyzed. MATERIALS AND METHODS: Two hundred and thirty-eight patients with unilateral acoustic neuromas who underwent Gamma knife radiosurgery between 1987-1994 with 6-91 months of follow-up (median 30 months) were studied. Minimum tumor doses were 12-20 Gy (median 15 Gy). Transverse tumor diameter varied from 0.3-5.5 cm (median 2.1 cm). The relationships of dose and diameter to the development of cranial neuropathies were delineated by multivariate logistic regression. RESULTS: The development of post-radiosurgery neuropathies affecting cranial nerves V, VII, and VIII were correlated with minimum tumor dose and transverse tumor diameter (P < 0.01 for all except Dmin for VIII where P = 0.10). A comparison of the dose-diameter response curves showed the acoustic nerve to be the most sensitive to doses of 12-16 Gy and the facial nerve to be the least sensitive. CONCLUSION: The risks of developing trigeminal, facial, and acoustic neuropathies following acoustic neuroma radiosurgery can be predicted from the transverse tumor diameter and the minimum tumor dose using models constructed from data presently available.

Cranial Nerve Diseases↗
PubMed1981

Tomography of the internal acoustic meatus. A critical evaluation of the radiological appearance in normals and in patients with acoustic neuromas.

The radiological appearance of the internal acoustic meatus, obtained by tomography of the temporal bone, is presented for 115 patients with normal inner-ear function. These patients served as normal controls, and their tomograms are compared with those obtained in 48 patients who were initially suspected of having acoustic neuromas but in whom Pantopaque cisternography was negative. These are also compared with the findings obtained in 59 patients with surgically-verified acoustic neuromas. In normal persons the size of the vertical diameter of the meatus on the two sides, as measured by tomography, differed in only a few cases by more than 1 mm. The results obtained in patients who were suspected of having a neuroma, but in whom Pantopaque cisternography had excluded such a diagnosis, coincided completely with the results found in the normal group, and a difference of more than 1 mm. between the right and left sides is therefore indicative of a pathological process in the internal and acoustic meatus. A normal meatus does not exclude the presence of a tumour, since 10 per cent of patients with neuromas have identical meatus. No evidence of radiological destruction was found, either in the normal material or in the group of patients suspected of having a neuroma. Destruction of the bone surrounding the meatus must therefore be regarded as highly suggestive of the presence of a tumour, but lack of destruction does not exclude a tumor. Tomography of the temporal bone should be applied routinely in the search for acoustic neuromas, in patients with unilateral acoustic or vestibular complaints. The evaluation of the tomograms, however, should be performed by a few, specially interested radiologists.

Adolescent↗
PubMedDate not supplied

Acoustic echoplanar scanner noise and pure tone hearing thresholds: the effects of sequence repetition times and acoustic noise rates.

PURPOSE: Our goal was to determine the effects of acoustic echoplanar scanner noise on pure tone hearing thresholds in normal volunteers and to determine the influence of echoplanar sequence repetition time on threshold effects. METHOD: With use of a calibrated audiometer, pure tones ranging from 125 to 8,000 Hz were delivered monaurally to 10 normal-hearing volunteers in a quiet MR scanner suite and in the presence of acoustic scanner noise produced by three separate single shot blipped echoplanar pulse sequences varying only in repetition time (TR = 1,000, 2,000, or 3,000 ms), with all other parameters including the number of slices held constant. The magnitude of noise-induced threshold changes and the slopes of the threshold curves produced by each of the three echoplanar pulse sequences were then analyzed using multiple comparisons and a least significant difference method. The shapes of the threshold curves produced in each background state were best fit using a quadratic effect for frequency in a mixed effects linear model and compared using F test statistics. RESULTS: All of the volunteers demonstrated entirely normal hearing thresholds throughout the full range of tonal frequencies tested (< 25 dB) when no acoustic scanner noise was present in the scanner suite. Pure tone hearing thresholds significantly increased (p < 0.01) in the presence of acoustic scanner noise, with the magnitude of change inversely proportional to the repetition time and therefore the rate of periodic noise production by the echoplanar sequence used. The shape of the threshold curve in the presence of noise produced by the 1,000 ms TR sequence was not equivalent across the frequency spectrum tested but had a quadratic distribution with peak effects at 750-2,000 Hz. As the repetition time was increased and the periodic noise rate decreased, the magnitude of the noise-induced threshold changes significantly lessened (p < 0.01) and the quadratic distributions of the threshold curves changed significantly (p < 0.01), tending toward a more planar configuration. CONCLUSION: Background acoustic echoplanar scanner noise can significantly increase pure tone thresholds in the optimal frequency hearing range (125-8,000 Hz). However, the threshold effects are not equivalent across the frequency spectrum, and the magnitude of threshold changes is dependent on the rate at which periodic acoustic scanner noises are produced for a given sequence repetition time.

Acoustic Stimulation↗
PubMed1987

Acoustic (loudspeaker) facial EMG monitoring: II. Use of evoked EMG activity during acoustic neuroma resection.

Facial electromyographic (EMG) activity was continuously monitored via loudspeaker during eleven translabyrinthine and nine suboccipital consecutive unselected acoustic neuroma resections. Ipsilateral facial EMG activity was synchronously recorded on the audio channels of operative videotapes, which were retrospectively reviewed in order to allow detailed evaluation of the potential benefit of various acoustic EMG patterns in the performance of specific aspects of acoustic neuroma resection. The use of evoked facial EMG activity was classified and described. Direct local mechanical (surgical) stimulation and direct electrical stimulation were of benefit in the localization and/or delineation of the facial nerve contour. Burst and train acoustic patterns of EMG activity appeared to indicate surgical trauma to the facial nerve that would not have been appreciated otherwise. Early results of postoperative facial function of monitored patients are presented, and the possible value of burst and train acoustic EMG activity patterns in the intraoperative assessment of facial nerve function is discussed. Acoustic facial EMG monitoring appears to provide a potentially powerful surgical tool for delineation of the facial nerve contour, the ongoing use of which may lead to continued improvement in facial nerve function preservation through modification of dissection strategy.

Adult↗
PubMed2003

Clinical results with the acoustic puncture assist device, a new acoustic device to identify the epidural space.

UNLABELLED: Sixty patients scheduled for lumbar epidural anesthesia were included in a study in which we evaluated the efficacy of localizing the epidural space by means of an acoustic signal. A prototype of an acoustic puncture assist device, connected to the epidural needle by an extension tube, generated the pressure needed to perform the epidural puncture and translated this pressure into corresponding acoustic and visible signals. The device frees the anesthesiologist to handle the epidural needle with both hands and to detect the epidural space by means of these signals. In all 60 patients (100%), the epidural space was successfully located by using the acoustic signal. In all cases, this was confirmed by the pressure measurement, which proved to be a reliable indicator for correct identification of the epidural space. We conclude that it is possible to locate the epidural space by means of the acoustic puncture assist device. The method proved to be reliable, safe, and simple in this study. The benefits of this new epidural puncture technique include better needle control, teaching, control of correct catheter placement, and documentation. The last can be an important adjunct to anesthesia practice. IMPLICATIONS: The authors demonstrate that it is possible to identify the epidural space by an acoustic and visible signal. An experimental setup constructed for this purpose makes the epidural puncture procedure audible and visible.

Acoustic Stimulation↗
PubMed1985

MR imaging of the acoustic nerves and small acoustic neuromas at 0.6 T: prospective study.

To evaluate the capability of magnetic resonance (MR) in imaging normal acoustic nerves, 12 volunteers without signs or symptoms of intracranial disease were examined using a 0.6 T superconductive system. Several spin-echo (SE) pulse sequences were tested to identify the optimal sequence for demonstration of the acoustic nerve bundle. Repetition times (TRs) varied from 300 to 2000 msec and echo times (TEs) from 30 to 120 msec. A single-slice technique was used with 5 and 8 mm sections, one or two data acquisitions per projection, and axial and coronal imaging. The normal acoustic nerves were demonstrated readily by MR in axial and/or coronal sections. The distal parts of the nerves and tumors were imaged best with SE 1500/60. The medial extremities of the seventh and eighth nerves tended to be obscured in this sequence by brightening the cerebrospinal fluid signal adjacent to the brainstem, but they were demonstrated clearly with 500 or 800 msec TR and 30 msec TE. Five patients were studied who had hearing loss and evidence of retrocochlear disease. In four patients, MR imaging demonstrated five acoustic nerve tumors ranging in size from purely intracanalicular to a 12 mm cisternal component. In the fifth case, no tumor was identified by MR imaging or gas computed tomographic (CT) cisternography. Contrast-enhanced CT using a Siemens Somatom DR 3 or GE CT/T 8800 scanner failed to provide convincing evidence of tumor in any case, while gas CT cisternography was positive in all five tumors. All five acoustic neuromas were identified readily using the SE sequences that proved optimal for demonstration of normal nerves. This experience revealed that MR imaging can demonstrate the eighth nerve complex well and reliably. Single-slice (5 or 8 mm) technique is adequate, but multislice without tissue gaps (used recently) is more efficient. Small, even intracanalicular, acoustic neuromas are imaged effectively, indicating that the method is capable of superseding contrast CT cisternography, particularly with improving technology.

Atrophy↗
PubMed1990

Influence of acoustic deprivation on recovery of hair cells after acoustic trauma.

The purpose of this study was to investigate how the recovery of the cochlea, after acoustic trauma, might be influenced by acoustic stimulation or deprivation. In anaesthetized adult chinchillas, both ears were simultaneously exposed to a traumatizing acoustic stimulus (2 kHz tone, at 117 dB SPL for 15 min). Probe microphones positioned in both bullae were used to ensure identical exposure to the two ears; this was important because the experiment relies on within-animal controls. Cochlear action potential thresholds across frequency (CAP audiograms) were used to verify the similarity of threshold shifts to the two ears. Immediately following, a unilateral ossiculectomy was performed which resulted in one cochlea being acoustically deprived during the recovery period, whilst the other was not. In groups of animals with recovery periods of 1, 3, 6, and 12 weeks, both the acoustically deprived and the normally stimulated cochleas were examined with scanning electron microscopy. To quantify hair cell damage, we used a damage scale based on stereociliar integrity; for each cochlea, a standard region 5.5-8.5 mm from the apex was studied in detail. We found that after acoustic trauma, hair cell damage to the cochlea which is deprived of sound during the recovery period, is significantly greater compared with that in the normally stimulated, contra-lateral cochlea. Our results suggest that mechanical activation of the inner ear acts to inhibit long-term degenerative processes, or influence repair of partially damaged hair cells.

Action Potentials↗