Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ACOUSTICS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
PubMed2006

Artificial neural network-based classification to screen for dysphonia using psychoacoustic scaling of acoustic voice features.

SUMMARY: For diagnosis and classification of dysphonia, voice specialists can choose from an array of diagnostic tools like perceptual tests or acoustic voice analysis. These methods have in common that they require a high level of specialized training and experience, and therefore are mostly reserved to specialized centers. We aimed at developing an acoustic voice analysis system that could be used as a screening device to monitor, document, and diagnose voice problems that are also encountered by non-voice specialists, such as anesthesiologists, head and neck surgeons, and general surgeons before surgery of the thyroid gland and the upper thoracic aperture. An acoustical feature extraction paradigm that focused on jitter, shimmer, standard deviation of fundamental frequency, and the glottal-to-noise excitation ratio was used to reanalyse 120 voice samples previously analyzed by Schönweiler et al (A Novel Approach to Acoustical Voice Analysis Using Artificial Neural Networks. JARO. 2000:1;270-282). An improved artificial neural network (ANN) was used for classification. Building on this preliminary work, we modified the mathematical algorithm to further improve classification accuracy. Eighty percent of all voice samples could be classified correctly as either healthy or hoarse (sensitivity: 63.0%; specificity: 93.9%; area under the curve: 0.854). The adaptation of the ANN-voice analysis system for mobile use may facilitate its use and acceptance by non-voice specialists for the discovery and documentation of preexisting voice disorders, and may thereby lead to a timely initiation of further diagnosis and therapy by voice specialists.

Diagnosis, Differential↗
PubMed2006

Differences in the response of a striped dolphin (Stenella coeruleoalba) and a harbour porpoise (Phocoena phocoena) to an acoustic alarm.

Small cetacean bycatch in gillnet fisheries may be reduced by deterring odontocetes from nets acoustically. However, different odontocete species may respond differently to acoustic signals from alarms. Therefore, in this study a striped dolphin and a harbour porpoise were subjected simultaneously to sounds produced by the XP-10 experimental acoustic alarm. The alarm produced 0.3s tonal signals randomly selected from a set of 16 with fundamental frequencies between 9 and 15kHz, with a constant pulse interval of 4.0s (duty cycle 8%) and a Source Level range of 133-163dB re 1muPa (rms). The effect of the alarm was judged by comparing the animals' respiration rate and position relative to the alarm during test periods with those during baseline periods. As in a previous study on two porpoises with the same alarm, the porpoise in the present study reacted strongly to the alarm by swimming away from it and increasing his respiration rate. The striped dolphin, however, showed no reaction to the active alarm. Based on harbour porpoise audiograms and the specific audiogram of the striped dolphin in the present study, and the low background noise levels during the experiment, both animals must have heard the alarm signals clearly. This study indicates that cetacean species are not equally sensitive to human-made noise disturbance. Therefore, source levels of acoustic alarms should be adapted to the species they are supposed to deter. In addition, alarms should be tested on each odontocete species for which they are intended to reduce bycatch.

Acoustic Stimulation↗
PubMed2006

Reaction time facilitation by acoustic task-irrelevant stimuli is not related to startle.

Previous research has been interpreted to suggest that the startle reflex mediates the RT facilitation observed if intense, accessory acoustic stimuli are presented coinciding with the onset of a visual imperative stimulus in a forewarned simple RT task. The present research replicated this finding as well as the facilitation of startle observed during the imperative stimulus. It failed, however, to find any relationship between the size of the blink startle reflex elicited by the accessory acoustic stimuli, which differed in intensity and rise time, and RT or RT facilitation observed on trials with accessory acoustic stimuli. This finding suggests that the RT facilitation is not mediated by the startle reflex elicited by the accessory acoustic stimuli.

Acoustic Stimulation↗
PubMed2006

Phonetic processing areas revealed by sinewave speech and acoustically similar non-speech.

The neural substrates underlying speech perception are still not well understood. Previously, we found dissociation of speech and nonspeech processing at the earliest cortical level (AI), using speech and nonspeech complexity dimensions. Acoustic differences between speech and nonspeech stimuli in imaging studies, however, confound the search for linguistic-phonetic regions. Presently, we used sinewave speech (SWsp) and nonspeech (SWnon), which replace speech formants with sinewave tones, in order to match acoustic spectral and temporal complexity while contrasting phonetics. Chord progressions (CP) were used to remove the effects of auditory coherence and object processing. Twelve normal RH volunteers were scanned with fMRI while listening to SWsp, SWnon, CP, and a baseline condition arranged in blocks. Only two brain regions, in bilateral superior temporal sulcus, extending more posteriorly on the left, were found to prefer the SWsp condition after accounting for acoustic modulation and coherence effects. Two regions responded preferentially to the more frequency-modulated stimuli, including one that overlapped the right temporal phonetic area and another in the left angular gyrus far from the phonetic area. These findings are proposed to form the basis for the two subtypes of auditory word deafness. Several brain regions, including auditory and non-auditory areas, preferred the coherent auditory stimuli and are likely involved in auditory object recognition. The design of the current study allowed for separation of acoustic spectrotemporal, object recognition, and phonetic effects resulting in distinct and overlapping components.

Adolescent↗
PubMed2005

Acoustic streaming in lithotripsy fields: preliminary observation using a particle image velocimetry method.

This study considers the acoustic streaming in water produced by a lithotripsy pulse. Particle image velocimetry (PIV) method was employed to visualize the acoustic streaming produced by an electromagnetic shock wave generator using video images of the light scattering particles suspended in water. Visualized streaming features including several local peaks and vortexes around or at the beam focus were easily seen with naked eyes over all settings of the lithotripter from 10 to 18 kV. Magnitudes of the peak streaming velocity measured vary in the range of 10-40 mm s(-1) with charging voltage settings. Since the streaming velocity was estimated on the basis of a series of the video images of particles averaged over 1/60s, the time resolution limited by the video frame rate which is 1-2 orders of magnitude larger than driving acoustic activities, measured velocities are expected to be underestimated and were shown a similar order of magnitude lower than those calculated from a simple theoretical consideration. Despite such an underestimation, it was shown that, as predicted by theory, the magnitude of the streaming velocity measured by the present PIV method was proportional to acoustic intensity. In particular it has almost a linear correlation with peak negative pressures (r=0.98683, p=0.0018).

Acoustics↗
PubMed2006

Combined phase-sensitive acoustic microscopy and confocal laser scanning microscopy.

Combined phase-sensitive acoustic microscopy (PSAM) at 1.2 GHz and confocal laser scanning microscopy (CLSM) in reflection and fluorescence has been implemented and applied to polymer blend films and fluorescently labeled fibroblasts and neuronal cells in order to explore the prospects and the various contrast mechanisms of this powerful technique. Topographic contrast is available for appropriate samples from CLSM in reflection and, with significantly higher precision, from the acoustic phase images. Material contrast can be gained from acoustic amplitude V(z) graphs. In the case of the biological cells investigated, the optical and acoustic images are very different and exhibit different features of the samples.

3T3 Cells↗
PubMed2004

Beam width measurements in low acoustic velocity phantoms.

Analysis of focused ultrasound (US) beams in low acoustic velocity phantoms demonstrates that beam width measurements yield results much larger than comparable measurements in phantoms with the correct acoustic velocity, 1540 m/s. These erroneous beam width measurements are shown to be due to two factors: a refocusing of the beam due to the low acoustic velocity (as compared with the design focus at 1540 m/s) and the necessary repositioning of the wire targets in these phantoms to simulate target depths in US phantoms with the proper acoustic velocity.

Acoustics↗
PubMed2006

Towards a reference ultrasonic cavitation vessel. Part 1: preliminary investigation of the acoustic field distribution in a 25 kHz cylindrical cell.

The acoustic field produced by a 25 kHz, 25 l cylindrical sonochemical processing cell has been characterised systematically using a sonar hydrophone, with the aim of establishing it as a reference test bed on which future investigations into acoustic cavitation activity may be based. Data acquired at sonication levels up to 500 W have shown that though significant cavitation activity is generated throughout the vessel, the acoustic field generated is reproducible, typically to +/- 12%. The increases in acoustic pressure are shown to be nonlinear with applied power, suggesting an intermediate optimum level for future study.

Acoustics↗
PubMed1997

Aberrant neuronal responsiveness in the genetically epilepsy-prone rat: acoustic responses and influences of the central nucleus upon the external nucleus of inferior colliculus.

The inferior colliculus (IC) central nucleus (ICc), is critical for audiogenic seizure (AGS) initiation in the genetically epilepsy-prone rat (GEPR). The ICc lacks direct motor outputs but sends a major projection to the external nucleus of IC (ICx), which does project to the sensorimotor integration nuclei within the AGS neuronal network. The present study compared acoustic responses of ICx neurons in the GEPR and normal anesthetized rat and evaluated whether the GEPR exhibits functional abnormalities in the pathway from ICc to ICx. There is a significantly greater incidence of sustained repetitive response patterns to the acoustic stimulus in GEPR ICx neurons (75%) than in normal ICx neurons (24%). Following unilateral microinjection of N-methyl-D-aspartate (NMDA) into the contralateral ICc, acoustically-evoked ICx excitation and inhibition were each increased in normal animals, which is consistent with the mixed projections previously reported in this pathway and observed with electrical stimulation in the present study. The NMDA-induced ICx firing increase may be relevant to AGS, since, in previous studies, bilateral focal microinjection of NMDA into the ICc induced AGS susceptibility in normal rats [23]. However, the incidence and degree of the ICx neuronal response changes after NMDA microinjection was not abnormal in the GEPR. These data suggest that the hyperresponsiveness of ICx neurons may not involve abnormal transmission between the ICc and ICx, despite the elevated ICx neuronal responses to acoustic stimuli. However, the ICx hyperresponsivess of the GEPR, which is likely due to the known decrease in effectiveness of GABA-mediated inhibition in GEPR neurons, may be a major mechanism subserving the critical role that this structure plays in the AGS network.

Acoustic Stimulation↗
PubMed1998

Acoustic transmission in the dentate nucleus. I. Patterns of activity to click and hiss; II. Changes in activity and excitability after conditioning.

Recordings were made from 95 units of the dentate nucleus of naive cats to determine if patterns of response to 70 dB clicks could be distinguished from those to another acoustic stimulus (a hiss) of approximately equal sound pressure level. Further studies of an additional 309 units were conducted to determine if unit excitability and the response to clicks changed after Pavlovian conditioning in which blink responses were elicited by the clicks as conditioned stimuli. Over 50% of units tested before conditioning responded to click or hiss with increased activity, and 8% responded in the first 4-8 ms after the onset of the rapidly rising click. Cross-correlation of the respective 160 ms poststimulus histogram averages of mean activity showed dissimilar patterns of response to clicks and hisses (Pearson product-moment correlation coefficient + 0.02). Thus the averaged population responses distinguished these stimuli. In addition, individual cells were found in each behavioral state that responded selectively to either click or hiss. After conditioning with click as the conditioned stimulus, the number of units responding in the first 4-8 ms to click increased to 23%. The mean magnitude of activity 4-8 ms after presenting the click increased after conditioning but not after sensitization produced by backward pairing of the stimuli used for conditioning. After backward pairing only 6% of the units responded in the first 4-8 ms to click. The changes in activity after conditioning were accompanied by increases in neural excitability to intracellularly applied depolarizing current. In contrast with the changes in activity, the increases in neural excitability were also found after backward pairing. We conclude that short as well as long latency acoustic transmissions to click change in the dentate nucleus after conditioning, that changes in response to click are expressed in 4-8 ms responsive cells, and that many of these cells have different patterns of spike activity in response to click and hiss. The findings support the hypothesis that the dentate nucleus can play a significant role in short as well as long latency, adaptive acoustic transmission that can enhance the response to an acoustic signal used as a Pavlovian conditioned stimulus.

Acoustic Stimulation↗
PubMed1999

Cholinergic modulation of the acoustic startle response in the caudal pontine reticular nucleus of the rat.

The startle response is a useful behavioural model to assess drug effects on sensorimotor information processing in the mammalian central nervous system. Prepulse inhibition of the acoustic startle response in rats is an operational measure for sensorimotor gating mechanisms which may be necessary for attention and response selection. The caudal pontine reticular nucleus is a key element of the pathway that mediates the acoustic startle response and receives an inhibitory cholinergic projection that might be important for prepulse inhibition. The present study tested whether prepulse inhibition of acoustic startle is modulated by microinfusions of the muscarinic/nicotinic acetylcholine receptor agonist carbachol and of the muscarinic acetylcholine receptor antagonist scopolamine. Carbachol (0-40 nmol/0.5 microl) dose dependently attenuated startle and enhanced prepulse inhibition. Scopolamine (0-40 nmol/0.5 microl) dose-dependently enhanced startle and reduced prepulse inhibition at a dose of 10 nmol. Scopolamine (40 nmol) also increased the spontaneous motor activity of the rats. These findings lend support to the hypothesis that muscarinic acetylcholine receptors in the caudal pontine reticular nucleus inhibit the acoustic startle response and are involved in the mediation of prepulse inhibition of startle.

Acoustic Stimulation↗
PubMedDate not supplied

Acoustic correlates of dysphonia: type and severity.

The purpose of this study was to explore the acoustic discrimination and graded severity of three clinical voice types. Listeners classified 102 samples of dysphonic vowels /a/ and /i/ on the basis of voice types: breathy, hoarse, and strained. The vowels were analyzed acoustically with two measures of perturbation and 2 measures of spectral noise. Discriminant analysis showed that apriori, acoustic classifications of voice type were made with 92% accuracy using four acoustic parameters: (a) cepstral peak prominence (CPP), (b) jitter standard deviation (SD-J), (c) fundamental frequency (F0), and (d) standard deviation of signal-to-noise ratio (SD-SNR). Findings suggest that voice type is associated with the interaction of spectral noise, fundamental frequency, and signal irregularity, and that dysphonic severity is associated with similar parameters, regardless of voice type.

Adolescent↗
PubMedDate not supplied

A comparison of clinical ratings with vocal acoustic measures of flat affect and alogia.

In this report we compare clinical ratings of flat affect and alogia with objective measures of the patient's speech prosody and productivity. Thirty schizophrenic patients were evaluated with the Scale for the Assessment of Negative Symptoms (SANS) and the St. Hans Rating Scale for extra pyramidal side effects. Their speech was recorded and analyzed acoustically for measures of prosody and productivity. Correlations between pairs of SANS items and acoustic measures (e.g. Vocal Inflection and Fundamental Frequency Variance) were weak. The SANS item and global ratings were strongly related. Ratings of bradykinesia overlapped with the SANS ratings but not with the acoustic measures. The SANS ratings appear to be derived from global impressions, with diffuse confounding of flat affect with alogia, and with bradykinesia. Acoustic analysis has the potential to provide objective measures that may help develop operational definitions of these constructs and enhance clinical assessment.

Adult↗
PubMed1996

Excitatory acoustic responses in the inferior colliculus of the rat are increased by GABAB receptor blockade.

This study sought to investigate the influence of GABAB receptor activation on acoustically induced excitation within the rat inferior colliculus. To this end, the GABAB receptor antagonist, CGP 35348, was applied systemically and iontophoretically. Single and multibarrel electrodes were used for extracellular recordings within the central nucleus of the inferior colliculus. The experimental model, a paired-pulse stimulus paradigm, applied two identical acoustic stimuli, 200 msec apart, evoking corresponding responses characterized by the second being consistently weaker than the first. Abolishment of the acoustically evoked response, following iontophoretic application of the GABAB receptor agonist, L-baclofen, verified the existence of GABAB receptors in all inferior colliculus cells tested. Intravenous application of CGP 35348 (200 mg/kg) evoked a 24% overall increase in stimulus responses. Likewise, a 13% increase in total evoked excitation was observed, following iontophoretic application. There was no significant reduction of inhibition on the second evoked response in the paired-pulse model, following either systemic or iontophoretic application of CGP 35348. This result implies that the decreased magnitude of the second response, with an interpulse interval of 200 msec, is not influenced by GABAB receptor mediated inhibition. These findings do indicate, however, that GABAB receptors play a small, but significant role during the processing of acoustic information, within the inferior colliculus.

Acoustic Stimulation↗
PubMed1980

Total one-stage suboccipital microsurgical removal of acoustic neuromas of all sizes: with emphasis on arachnoid planes and on saving the facial nerve.

Clinical suspicion is essential for early diagnosis of acoustic neuroma. No absolutely characteristic pattern of hearing loss occurs, and atypical presentations are the rule. The diagnosis of acoustic neuroma is possible by tests that can be performed on an outpatient basis. A hearing loss for high tones with impaired speech discrimination is frequently seen. Testing of the acoustic reflexes and particularly the brain stem auditory-evoked responses (BAER) are becoming the most reliable methods of defining hearing loss in patients suspected of having an acoustic neuroma. High-resolution, thin-sectioning, overlapping-cut CT scanning including CT pneumography when necessary and polytomography of the internal auditory meatus are the mainstays of radiologic evaluation. Complete removal of the tumor at one operation is usually possible by the suboccipital retromastoid route with preservation or restoration of normal brain stem function and preservation of facial nerve function. Preservation of hearing has occasionally been accomplished, and the potential occasionally exists for restoration of hearing in patients with favorable smaller tumors, which have not acquired extensive arterial supply in common with the cochlea. The two factors that most influence results are early diagnosis and gentleness of surgical manipulation of the tissues that is made possible by magnification and illumination with the operating microscope.

Arachnoid↗
PubMed2003

Principal surface wave velocities in the point focus acoustic materials signature V(z) of an anisotropic solid.

This paper deals with the point focus beam (PFB) acoustic materials signature V(z) of an anisotropic solid, and in particular how it tends to be dominated by a limited number of principal surface rays. These rays are associated with propagation directions in which the Rayleigh wave (RW), pseudo-surface acoustic wave (PSAW) or a lateral wave slowness has an extremum. The phenomenon is interpreted in terms of the complex azimuthally averaged reflectance function of the surface, and also explained on the basis of a ray model. We illustrate the phenomenon with a number of examples, pertaining to the surfaces of single crystal copper and a carbon-fibre epoxy composite. In the case of copper, which has a much larger acoustic impedance than the water couplant, the oscillations in V(z) are dominated by principal RW and PSAW, whereas for the composite there is no RW or pseudo-SAW to be discerned with acoustic microscopy (AM), and V(z) is dominated by principal lateral waves. The utility of PFB AM in the study of anisotropic solids is further elaborated with examples showing how V(z) is sensitive to surface orientation, and how V(z) is affected by the presence of a surface over layer. The phenomena examined in this paper expand the scope for determining materials characteristics, such as elastic constants, crystallographic orientation, residual stress and over layer properties, from PFB V(z) measurements.

Anisotropy↗
PubMed1993

Quantitative comparison of electrically and acoustically evoked auditory perception: implications for the location of perceptual mechanisms.

Electrical stimulation of the human auditory system produces different patterns of spatial and temporal neural activity than those that occur in the normal, acoustically stimulated system. Quantitative comparison of psychophysical performance measured with acoustic and electrical stimulation may allow us to infer the physiological locus of perceptual mechanisms. In this paper we compare psychophysical data on temporal resolution from normal-hearing listeners, cochlear implant listeners, and patients electrically stimulated on the cochlear nucleus. Measures of gap detection, forward masking, and modulation detection will be compared. These comparisons demonstrate that temporal processing is relatively similar across these three groups once the obvious differences in dynamic range are taken into consideration. In addition, preliminary results with speech processors indicate that implant patients can utilize all temporal information in speech. Thus, implant patients have relatively normal temporal resolution and can integrate temporal cues normally for the recognition of complex acoustic patterns such as speech. These results imply that the central auditory systems of implant patients are able to fully utilize the non-natural patterns of temporal neural information produced by electrical stimulation. The differences in the microstructure of the neural pattern (phase locking, stochastic independence of fibers, spatial distribution of activity, etc.) between electrical and acoustic stimulation are apparently not necessary for temporal processing. Thus, the physiological locus of temporal processing mechanisms must be more central in the auditory system than the cochlea and cochlear nucleus.

Acoustic Stimulation↗
PubMed1999

Suboccipital resection of a medial acoustic neuroma with hearing preservation.

BACKGROUND: Many reports indicate that acoustic neuromas greater than 2.0 cm should be removed without hearing preservation attempted, even if hearing is present preoperatively. These studies advocate a translabyrinthine approach because the likelihood of hearing preservation is low. Medial acoustic neuromas, unlike the more common lateral tumors that involve the internal auditory canal, originate medial to that portion of the eighth nerve complex where the cochlear and vestibular nerves are fused. This anatomical feature suggests that these tumors may be amenable to resection with hearing preservation. METHODS: A patient with a 3.5 cm medial acoustic neuroma and useful preoperative hearing is presented. RESULTS: Gross total tumor removal with functional hearing was achieved after a two-stage procedure using a suboccipital approach. CONCLUSION: Based on the anatomico-pathologic features in this case, we believe that, if a patient has reasonable preoperative hearing (speech discrimination score > 70%) and a medial acoustic neuroma, an approach to preserve hearing should be considered regardless of tumor size.

Female↗