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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↗
PubMed2005

A theoretical study of the feasibility of acoustical tweezers: ray acoustics approach.

The optical tweezer has been found to have many biomedical applications in trapping macromolecules and cells. For the trapping mechanism, there has to be a sharp spatial change in axial optical intensity and the particle size must be much greater than the wavelength. Similar phenomenon may exist in acoustics. This work was undertaken to demonstrate theoretically that it is possible to acoustically trap particles near the focal point where most of the acoustic energy is concentrated if certain conditions are met. Acoustic force exerted on a fluid particle in ultrasonic fields is analyzed in a ray acoustics regime where the wavelength of acoustic beam is much smaller than the size of the particle. In order to apply the acoustical tweezer to manipulating macromolecules and cells whose size is in the order of a few microns or less, a prerequisite is that the ultrasound wavelength has to be much smaller than a few microns. In this paper, the analysis is therefore based on the field pattern produced by a strongly focused 100 MHz ultrasonic transducer with Gaussian intensity distribution. For the realization of acoustic trapping, negative axial radiation force has to be generated to pull a particle towards a focus. The fat particle considered for acoustic trapping in this paper has an acoustic impedance of 1.4 MRayls. The magnitude of the acoustic axial radiation force that has been calculated as the size of the fat particle is varied from 8lambda to 14lambda. In addition, both Fresnel coefficients at various positions are also calculated to assess the interaction of reflection and refraction and their relative contribution to the effect of the acoustical tweezer. The simulation results show that the feasibility of the acoustical tweezer depends on both the degree of acoustic impedance mismatch and the degree of focusing relative to the particle size.

Acoustics↗
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↗
PubMed2004

Statistical-acoustics models of energy decay in systems of coupled rooms and their relation to geometrical acoustics.

An improved statistical-acoustics model of high-frequency sound fields in coupled rooms is developed by incorporating into prior models geometrical-acoustics corrections for both energy decay within subrooms and energy transfer between subrooms. The conditions under which statistical-acoustics models of coupled rooms are valid approximations to geometrical acoustics are examined by comparison of computational geometrical-acoustics predictions of decay curves in two- and three-room systems with those of both improved and prior statistical-acoustics models. The accuracy of the decay model used within subrooms is found to have a primary influence on the accuracy of predictions in coupled systems. Likewise, nondiffuse transfer of energy is shown to significantly affect decay of energy in systems of coupled rooms. The decrease in energy density of the reverberant field with distance from the source, which is predicted by geometrical acoustics, is found to result in spatial dependence of decay-curve shape for certain coupling geometries. Geometrical effects are shown to contribute to the failure of statistical-acoustics models in the case of strong coupling between subrooms; thus, previously proposed statistical-acoustics criteria cannot predict the point at which the models break down with consistent accuracy.

Acoustics↗
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↗
PubMed2004

Patient perception of comorbid conditions after acoustic neuroma management: survey results from the acoustic neuroma association.

OBJECTIVES/HYPOTHESIS: Based on survey results of the Acoustic Neuroma Association, the patient ratings of the most difficult aspects of acoustic neuroma management were reported and a review of the literature was made regarding comorbid conditions associated with acoustic neuroma treatment and their impact on patient quality of life. STUDY DESIGN: Cohort study of 1940 patients who were members of the Acoustic Neuroma Association. METHODS: A detailed questionnaire was mailed to 2372 members of the Acoustic Neuroma Association to identify preoperative and postoperative symptoms, complications, and long-term effects on physical and psychosocial function. For 1940 respondents (81.8%) who reported the "most difficult aspect of the AN [acoustic neuroma] experience," the responses were analyzed by tumor size, surgical approach, and patient age and sex. Statistical analysis was performed using SPSS software. RESULTS: Respondents reported that the most difficult aspect of the acoustic neuroma experience was hearing loss (25.8%), followed by facial weakness (17.9%), eye problems (10.8%), and headache (10.5%). In order of frequency, men reported hearing loss, balance problems, perioperative surgical experience, and eye and facial weakness, and women reported hearing loss, facial weakness, eye problems, and headache. Facial weakness was a morbidity more often reported for men and women who had large tumors, who were young, or who had undergone the retrosigmoid approach. Balance dysfunction was significant in patients older than 75 years of age. In patients with small tumors, headaches and balance problems were frequently reported. CONCLUSION: In the large cohort study of patients with acoustic neuroma, perceptions regarding the impact of treatment illustrated why it is incumbent on physicians to understand the sentiments of patients with acoustic neuroma when counseling them and recommending optimal management strategies.

Aged↗
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↗
PubMed2005

Acoustic simulations of combined electric and acoustic hearing (EAS).

OBJECTIVE: Our aim was to explore the consequences for speech understanding of leaving a gap in frequency between a region of acoustic hearing and a region stimulated electrically. Our studies were conducted with normal-hearing listeners, using an acoustic simulation of combined electric and acoustic (EAS) stimulation. DESIGN: Simulations of EAS were created by low-pass filtering speech at 0.5 kHz (90 dB octave roll-off) and adding amplitude-modulated sine waves at higher frequencies. The gap in frequency between acoustic and simulated electric hearing was varied over the range 0.5 kHz to 3.2 kHz. Stimuli included sentences in quiet, sentences in noise, and consonants and vowels. Three experiments were conducted with sample sizes of 12 listeners. RESULTS: Scores were highest in conditions that minimized the frequency gap between acoustic and electric stimulation. In quiet, vowels and consonant place of articulation showed the most sensitivity to the frequency gap. In noise, scores in the simulated EAS condition were higher than the sum of the scores from the acoustic-only and simulated electric-only conditions. CONCLUSIONS: Our results suggest that both deep and shallow insertions of electrodes could improve the speech understanding abilities of patients with residual hearing to 500 Hz. However, performance levels will be maximized if the gap between acoustic and electric stimulation is minimized.

Acoustic Stimulation↗
PubMed2006

Restoration of acoustic orienting into a cortically deaf hemifield by reversible deactivation of the contralesional superior colliculus: the acoustic "Sprague Effect".

Removal of all contiguous visual cortical areas of one hemisphere results in a contralateral hemianopia. Subsequent deactivation of the contralesional superior colliculus (SC) nullifies the effects of the visual cortex ablation and restores visual orienting responses into the cortically blind hemifield. This deficit nullification has become known as the "Sprague Effect." Similarly, in the auditory system, unilateral ablation of auditory cortex results in severe sound localization deficits, as assessed by acoustic orienting, to stimuli in the contralateral hemifield. The purpose of this study was to examine whether auditory orienting responses can be restored into the impaired hemifield during deactivation of the contralesional SC. Three mature cats were trained to orient toward and approach an acoustic stimulus (broadband, white noise burst) that was presented centrally, or at one of 12 peripheral loci, spaced at 15 degrees intervals. After training, a cryoloop was chronically implanted over the dorsal surface of the right SC. During cooling of the cooling loop to temperatures sufficient to deactivate the superficial and intermediate layers (SZ, SGS, SO, SGI), auditory orienting responses were eliminated into the left (contracooled) hemifield while leaving acoustic orienting into the right (ipsicooled) hemifield unimpaired. This deficit was temperature-dependently graded from periphery to center. After the effectiveness of the SC cooling loop was verified, auditory cortex of the middle and posterior ectosylvian and anterior and posterior sylvian gyri was removed from the left hemisphere. As expected, the auditory cortex ablation resulted in a profound deficit in orienting to acoustic stimuli presented at any position in the right (contralesional) hemifield, while leaving acoustic orienting into the left (ipsilesional) hemifield unimpaired. The ablations of auditory cortex did not have any impact on a visual detection and orienting task. The additional deactivation of the contralesional SC to temperatures sufficient to cool the superficial and intermediate layers nullified the deficit caused by the auditory cortex ablation and acoustic orienting responses were restored into the right hemifield. This restoration was temperature-dependently graded from center to periphery. The deactivations were localized and confirmed with reduced uptake of radiolabeled 2-deoxyglucose. Therefore deactivation of the right superior colliculus after the ablation of the left auditory cortex yields a fundamentally different result from that identified during deactivation of the right superior colliculus before the removal of left auditory cortex in the same animal. Thus the "Sprague Effect" is not unique to a particular sensory system and deactivation of the contralesional SC can restore either visual or acoustic orienting responses into an impaired hemifield after cortical damage.

Acoustic Stimulation↗
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↗
PubMedDate not supplied

The application of the acoustic spectrophonometer to biomolecular spectrometry: a step towards acoustic "fingerprinting".

A tunable acoustic biosensor for investigating the properties of biomolecules at the solid-liquid interfaces is described. In its current, format the device can be tuned to frequencies between 6.5 MHz and 1.1 GHz in order to provide a unique detection feature: a variable evanescent wave thickness at the sensor surface. The key to its successful implementation required the careful selection of antennae designs that could induce shear acoustic waves at the solid-liquid interface. This non-contact format makes it possible to recover resonant shear acoustic waves over 100 different harmonic frequencies as a result of the electrical characteristics of the spiral coil. For testing this multifrequency sensing concept the surface of a quartz disc was exposed to solutions of immunoglobulin G (IgG) to form an adsorbed monolayer, whence protein A and IgG were added again in order to form multilayers. Spectra at frequencies between 6 and 600 MHz were generated for each successive layer and revealed two characteristic phases: an initial phase at the low megahertz frequencies consistent with the conventional Sauerbrey relation, and a possible additional phase towards the high megahertz to gigahertz frequencies, that we believe relates to the structure of the biomolecular film. This two-phase behaviour evident from differences between high and low frequencies, rather than from any distinct frequency transition, was anticipated from the reduction in evanescent wave thickness down to nanometre dimensions, and thin film resonance phenomena that are known to occur for film and fluid systems. These measurements suggested that the single element acoustic biosensor we present here may form the basis from which to generate acoustic molecular spectra, or "acoustic fingerprints", in a manner akin to optical spectroscopy.

Acoustics↗
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↗