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 1,009 records · Page 56Linked to original sources
PubMed2000

Effects of simulated source of tremor on acoustic and airflow voice measures.

To test the effects of different sources of tremor on the voice, tremor was simulated by external rhythmic perturbation of structures at the subglottal, glottal, and supraglottal levels in 10 healthy subjects. The acoustic and airflow signals simultaneously recorded during sustained phonation in the normal and the 3 simulated tremor conditions were analyzed and compared. Voice measures included: fundamental frequency, 2 short-term perturbation measures (jitter and shimmer), and 3 long-term tremor measures (prominence ratios of the spectral peaks of the acoustic frequency contour, acoustic amplitude contour, and airflow contour). Measures of fundamental frequency and percent shimmer were not significantly affected by the simulated tremors. Measures of percent jitter and the amplitudes of the long-term frequency and amplitude modulations were most prominently increased when respiratory drive was perturbed by simulated tremor. Spectral analysis of the acoustic amplitude contour was most useful in distinguishing the 3 sites of simulated tremor.

Adolescent↗
PubMed1995

Acoustic concomitants of emotional expression in operatic singing: the case of Lucia in Ardi gli incensi.

Two excerpts from the cadenza in Ardi gli incensi from Donizetti's opera Lucia di Lammermoor were acoustically analyzed for five recorded versions of the cadenza by Toti dal Monte, Maria Callas, Renata Scotto, Joan Sutherland, and Edita Gruberova. These acoustic parameters of the singing voices were correlated with preference and emotional expression judgments, based on pairwise comparisons, made by a group of experienced listener-judges. In addition to showing major differences in the voice quality of the five "dive" studied, the acoustic parameters suggested which vocal cues affect listener judgments. Two component scores, based on a factorial-dimensional analysis of the acoustic parameters, predicted 84% of the variance in the preference ratings.

Affect↗
PubMed1996

Performance effects on the voices of 10 choral tenors: acoustic and perceptual findings.

Trained choral tenors performed a series of vocal tasks before and after a "live" performance. Acoustic (perturbation, harmonic-to-noise ratio, pitch and amplitude ranges) and perceptual analyses (auditory and proprioceptive/kinesthetic) were undertaken to detect changes from pre- to postperformance. Individuality of response to the performance was revealed, with the majority of subjects showing vocal deterioration after performance. The most sensitive vocal tasks were the comfortably pitched notes, high soft notes, and the bottom notes in scale singing. The most sensitive acoustic measure in detecting change from pre- to postperformance was harmonic-to-noise ratio. In contrast to the demonstrated acoustic changes, no significant differences in perceptual ratings were evident after the performance. Perceptual ratings did not reflect the acoustic analysis results. The present study highlights the need to establish further normative data for the singing voice and to consider individual differences in vocal characteristics in future studies of the singing voice.

Adult↗
PubMed1999

The effects of excessive vocalization on acoustic and videostroboscopic measures of vocal fold condition.

Although dysphonia is a recognized consequence of acute vocal abuse, associated changes in vocal fold appearance and function are not well understood. To document these presumed effects of vocal abuse, audio recordings of sustained vowel production were obtained from 42 drill sergeants daily during the first 6 days of a vocally demanding training exercise. Acoustic analysis showed abnormal levels of jitter and shimmer on Day 1 in 16 of the 42 subjects. Considering only the 26 subjects who showed normal voice acoustics on Day 1, the median levels of jitter and shimmer varied little over the course of training, and significant increases in jitter and shimmer were not seen during the study period. However, the distributions for both jitter and shimmer became more positively skewed and showed a greater number of positive outliers over the course of training. This trend was attributed to 11 subjects who showed two or more instances of abnormal voice acoustics over Days 2 through 6. Laryngeal videostroboscopic recordings of sustained vowel production also were obtained prior to and following training. Perceptual ratings of these recordings by 2 observers revealed significant increases in vocal fold edema, erythema, and edge irregularity, and decreases in vocal fold mucosal wave and amplitude of excursion following the 5-day training period. In general, there was considerable intersubject variability in the extent of acoustic and videostroboscopic effects over the course of training. Of the two types of data, videostroboscopy appears to provide a more sensitive indication of the effects of excessive vocalization.

Adult↗
PubMed1998

Estimation of acoustical streaming: theoretical model, Doppler measurements and optical visualisation.

An approximate solution for the streaming velocity generated by flat and weakly focused transducers was derived by directly solving the Dirichlet boundary conditions for the Poisson equation, the solution of the Navier-Stokes equation for the axial components of the streaming velocity. The theoretical model was verified experimentally using a 32 MHz pulsed Doppler unit. The experimental acoustical fields were produced by three different 4 mm diameter flat and focused transducers driven by the transmitter generating the average acoustic power within the range from 1 microW to 6 mW. The streaming velocity was measured along the ultrasonic beam from 0 to 2 cm. Streaming was induced in a solution of water and corn starch. The experimental results showed that for a given acoustic power the streaming velocity was independent of the starch density in water, changed from 0.3 to 40 grams of starch in 1 l of distilled water. For applied acoustic powers, the streaming velocity changed linearly from 0.2 to 40 mm/s. Both, the theoretical solutions for plane and focused waves and the experimental results were in good agreement. The streaming velocity field was also visualised using the particle image velocimetry (PIV) and two different evaluation methods. The first based on the FFT-based cross-correlation analysis between small sections for each pair of images and the second employing the algorithm of searching for local displacements between several images.

Acoustics↗
PubMed1983

Acoustic neuromas (diagnostic value of testing the function of the trigeminal nerve, the cerebellum and optokinetic nystagmus).

The involvement of the trigeminal nerve, cerebellum, and optokinetic nystagmus in patients with acoustic neuromas, as well as the methods of investigation, are described. The corneal and/or facial sensibility was found to be reduced in 29 per cent of the whole series and in 53 per cent of tumors larger than 40 mm. There was a significant correlation between reduced corneal and/or facial sensibility and the findings of pressure at the trigeminal root at operation. Only three patients had a persistent reduction of trigeminal function post-operatively. Cerebellar dysfunction was found in 32 per cent, but significantly more frequently (58 per cent) in patients with tumors larger than 40 mm. Post-operatively, six patients had cerebellar symptoms in the form of gait disturbances; five of these patients had a supplementary suboccipital removal performed, after the initial translabyrinthine approach. A defective optokinetic nystagmus was found pre-operatively in 10 patients, nine of whom had tumors larger than 40 mm in diameter. All patients with a defective optokinetic nystagmus had a large anatomic impression in the pons at operation. In patients suspected of having an acoustic neuroma, symptoms from the trigeminal nerve, the cerebellum and the optokinetic nystagmus predict the presence of a large tumor and subsequent difficulties at operation. The symptoms were completely reversible in the vast majority of cases and post-operative symptoms persisted only in patients in whom tumor removal was difficult and the tumor very large. Testing of the trigeminal nerve, the cerebellum and the optokinetic nystagmus still deserves its place in the diagnostic work-up of patients with unilateral acoustic or vestibular symptoms, especially in cases with severe hearing impairment, which necessitate the use of tests that are independent of acoustic function.

Adult↗
PubMed2001

A strategy for chemical sensing based on frequency tunable acoustic devices.

A new acoustic sensor geometry, the magnetic acoustic resonant sensor (MARS), is described. The device comprises a circular 0.5-mm-thick resonant plate fabricated from a wide variety of nonpiezoelectric materials and coated on the underside with a 2.5-microm-thick aluminum film. Harmonic radial shear waves over at least a 2 orders of magnitude frequency range can be induced in the resonant plate by enhanced magnetic direct generation using a noncontacting rf coil and NdFeB magnet. Mass loading with adherent aluminum films produced frequency changes of 106 Hz/nm (40.8 Hz/ng-mm(-2)), while contact with viscous fluids resulted in maximum changes of 15 446 Hz/cP. At an operating frequency of 50 MHz, the device detected viscosity changes as low as 0.0006 cP. The adsorption of proteins such as human IgG and the binding of a complementary antigen, goat anti-human IgG, on the upper nonmetallized surface of the device has been monitored with a detection limit of approximately 75 ng/mL. The binding of substrates and allosteric effectors to glycogen phosphorylase b has provided evidence that the device is very sensitive to viscoelastic changes in adsorbed proteins. The MARS device generates radial shear acoustic waves over a broad bandwidth that are unaffected by the conductivity of the solution. These results suggest that simple metal, glass, crystalline, or polycrystalline plates can be used as a new type of tunable acoustic immunosensor.

Acoustics↗
PubMed2002

RNA-peptide binding and the effect of inhibitor and RNA mutation studied by on-line acoustic wave sensor.

Acoustic wave devices of the transverse shear-wave type are becoming increasingly important in the study of biochemical binding events at the solid-liquid interface in real time. The operation of the sensor is based on the principle that perturbations occurring at the solid-liquid interface result in changes in the propagating characteristics of the acoustic wave. The binding of the human immunodeficiency virus-type 1 Tat protein to the transactivation-responsive RNA element has been studied using this sensor. Variable acoustic signals in terms of frequency and motional resistance changes are obtained when surface-immobilized RNA is challenged by different peptide fragments derived from Tat protein. The effect of peptide concentration and mutation in addition to the inhibition of RNA-peptide binding by neomycin has been investigated. The results of this study suggest that acoustic physics offers considerable potential for the screening of small-molecule interactions with nucleic acids.

Acoustic Stimulation↗
PubMedDate not supplied

Batch and semicontinuous aggregation and sedimentation of hybridoma cells by acoustic resonance fields.

Ultrasound was used to enhance the sedimentation of hybridoma cells from medium in a 75 mL resonator chamber. Forces in the acoustic standing waves aggregated the cells, and the aggregates were then rapidly sedimented by gravity. Cell separation increased with acoustic treatment time and cell concentration. The separation efficiency was over 97% for cell concentrations between 10(6) and 10(7) cells/mL. During acoustic treatment at 180 W/L, the medium temperature increased at a rate of 1.3 degrees C/min. Ultrasonic exposures up to 220 W/L did not influence the viability or subsequent growth and antibody production of the cells. A decrease in cell viability was observed at a power level of 260 W/L. Batch separation efficiencies were as high as 98%. Acoustic separation was tested under semicontinuous operation, and above 90% separation efficiency was achieved at a flow rate of 0.7 L/h.

Acoustics↗
PubMedDate not supplied

Optimization of an acoustic cell filter with a novel air-backflush system.

Increasing worldwide demand for mammalian cell production capacity will likely be partially satisfied by a greater use of higher volumetric productivity perfusion processes. An important additional component of any perfusion system is the cell retention device that can be based on filtration, sedimentation, and/or acoustic technologies. A common concern with these systems is that pumping and transient exposure to suboptimal medium conditions may damage the cells or influence the product quality. A novel air-backflush mode of operating an acoustic cell separator was developed in which an injection of bioreactor air downstream of the separator periodically returned the captured cells to the reactor, allowing separation to resume within 20 s. This mode of operation eliminated the need to pump the cells and allows the selection of a residence time in the separator depending on the sensitivity of the cell line. The air-backflush mode of operating a 10L acoustic separator was systematically tested at 10(7) cells/mL to define reliable ranges of operation. Consistent separation performance was obtained for wide ranges of cooling airflow rates from 0 to 15 L/min and for backflush frequencies between 10 and 40 h(-1). The separator performance was optimized at a perfusion rate of 10 L/day to obtain a maximum separation efficiency of 92 +/- 0.3%. This was achieved by increasing the power setting to 8 W and using duty cycle stop and run times of 4.5 and 45 s, respectively. Acoustic cell separation with air backflush was successfully applied over a 110 day CHO cell perfusion culture at 10(7) cells/mL and 95% viability.

Acoustics↗
PubMedDate not supplied

Retention and viability characteristics of mammalian cells in an acoustically driven polymer mesh.

A processing approach for the collection and retention of mammalian cells within a high porosity polyester mesh having millimeter-sized pores has been studied. Cell retention occurs via energizing the mesh with a low intensity, resonant acoustic field. The resulting acoustic field induces the interaction of cells with elements of the mesh or with each other and effectively prevents the entrainment of cells in the effluent stream. Experiments involving aqueous suspensions of polystyrene particles were used to provide benchmark data on the performance of the acoustic retention cell. Experiments using mouse hybridoma cells showed that retention densities of over 1.5 x 10(8) cell/mL could be obtained. In addition, the acoustic field was shown to produce a negligible effect on cell viability for short-term exposure.

Acoustics↗
PubMed1997

The acoustic startle response in inbred Roman high- and low-avoidance rats.

To investigate the emotional reactions of two rat strains selectively bred for good and poor two-way avoidance acquisition (RHA/Verh and RLA/Verh), male animals of both strains were tested in an acoustic startle response test. They received 40 acoustic stimuli followed by 10 electric foot shocks and another 30 acoustic stimuli. RLA/Verh rats showed a significantly higher startle response compared to RHA/Verh animals, indicating a stronger emotional reaction to acoustic stimuli. In addition, the former showed a stronger response to foot shocks. Combined with earlier findings, we conclude that selection for two-way avoidance learning does not result in cognitive defects in the RLA/Verh strain but, rather, in stronger emotional reactions to fearful stimuli.

Acoustic Stimulation↗
PubMed1981

Acoustic augmentation and inhibition of the human eyeblink.

The human eyeblink elicited by a mechanically produced tap to the glabella was inhibited by a mild acoustic stimulus presented 200 msec prior to the tap and was augmented when the same acoustic stimulus was presented simultaneously with the tap. Monaural presentation of the acoustic stimulus prior to the tap yielded more reflex inhibition than when that same stimulus was presented binaurally. Binaural presentation of the acoustic stimulus simultaneously with the tap yielded more reflex augmentation than when that same stimulus was presented monaurally. These findings lend credence to the proposition that reflex inhibition and reflex augmentation are mediated by separate neural pathways.

Acoustic Stimulation↗
PubMed2004

Implicit learning of musical timbre sequences: statistical regularities confronted with acoustical (dis)similarities.

The present study investigated the influence of acoustical characteristics on the implicit learning of statistical regularities (transition probabilities) in sequences of musical timbres. The sequences were constructed in such a way that the acoustical dissimilarities between timbres potentially created segmentations that either supported (S1) or contradicted (S2) the statistical regularities or were neutral (S3). In the learning group, participants first listened to the continuous timbre sequence and then had to distinguish statistical units from new units. In comparison to a control group without the exposition phase, no interaction between sequence type and amount of learning was observed: Performance increased by the same amount for the three sequences. In addition, performance reflected an overall preference for acoustically similar timbre units. The present outcome extends previous data from the domain of implicit learning to complex nonverbal auditory material. It further suggests that listeners become sensitive to statistical regularities despite acoustical characteristics in the material that potentially affect grouping.

Acoustics↗
PubMedDate not supplied

Genetic linkage of bilateral acoustic neurofibromatosis to a DNA marker on chromosome 22.

Bilateral acoustic neurofibromatosis (BANF) is a severe autosomal dominant disorder involving development of multiple tumours of the nervous system including meningiomas, gliomas, neurofibromas and particularly bilateral acoustic neuromas. We have used genetic linkage analysis with DNA markers to establish that the defective gene causing BANF is on chromosome 22, and is therefore distinct from the gene for the von Recklinghausen form of neurofibromatosis, which maps to chromosome 17. Linked DNA markers will be particularly valuable in BANF, facilitating early detection of tumours and thereby permitting more effective surgical intervention. In view of the reported loss of genes on chromosome 22 in meningiomas and acoustic neuromas, the genetic localization of the primary BANF defect strongly supports the concept that the disease locus encodes a 'tumour suppressor' gene. Isolation of this gene should provide insights into the pathogenesis of acoustic neuromas and other nervous system tumours, as well as into the control of proliferation and differentiation of neural crest cells.

Chromosome Mapping↗
PubMed2003

Prostate cancer transfection by acoustic energy using pEGFP-N1 as reporter gene in the solid Dunning R-3327-MatLu tumor.

BACKGROUND: Gene therapy is expected to play a major role in medical treatment in the future. Several different methods for DNA transfection exist. We evaluated the efficacy and effects of transfection by acoustic energy in a standardized prostate cancer model. METHODS: Subcutaneous implantation of Dunning tumors was followed by injection of pEGFP-DNA plasmid. Tumors were treated by acoustic energy with different parameter settings and the transfection rate was assessed by FACScan. RESULTS: Standardized experimental conditions resulted in minor intragroup deviations. Intratumoral injection resulted in a transfection rate of 0.3% (control group). The statistically significant increase of 4.6% in cell transfection rate was gained by applying acoustic energy. CONCLUSIONS: DNA transfection of solid tumors can be mediated by the application of acoustic energy. Achieved transfection rates are encouraging and imply therapeutical levels. Prodrug activation or suicide gene therapy are possible fields of investigation in the treatment of prostate cancer.

Acoustics↗
PubMed2004

Acoustic micromachining of three-dimensional surfaces for biological applications.

We present the use of an accessible micromachining technique (acoustic micromachining) for manufacturing micron-feature surfaces with non-discretely varying depth. Acoustic micromachining allows for non-photolithographic production of metal templates with programmable spatial patterns and involves the use of standard acoustic, cutting and electroplating equipment for mass production of vinyl records. Simple 3D patterns were transferred from an acoustic signal into working nickel templates, from which elastic polymer molds were obtained, featuring deep surface grooves and non-discrete (smooth) variations in the z-dimension. Versatility and applicability of the method is demonstrated in obtaining microfluidics structures, manufacturing high-surface area wavy polymer fibers, assembly of cell networks on scaffolds with 3D topography, and microcontact printing of proteins and cells.

Acoustics↗
PubMed2005

Factors affecting broadband acoustic emission measurements of a heterogeneous reaction.

Broadband acoustic emission signals were obtained by attaching a piezoelectric transducer, sensitive up to 750 kHz, to the external wall of a 1 L jacketed glass reactor. Measurements were acquired of itaconic acid particles mixing in toluene; the total area of the acoustic emission signal from 55-500 kHz increased when the particle concentration, particle size or stir rate were increased. Signals at frequencies above 200 kHz were less sensitive to changes in particle size than those at lower frequencies. From calculation of the area of the signal in the range 55-200 kHz as a percentage of the signal area over the range 55-500 kHz, for mixtures of different size ranges of itaconic acid, it was possible to obtain an estimate of the mean particle size of a mixture. The heterogeneous esterification reaction of itaconic acid and 1-butanol was monitored non-invasively. A decrease in the overall acoustic signal area between 60 and 500 kHz was observed as the reaction progressed. Particle size and concentration information were contained in the amplitude of the acoustic emission signal, while the emission frequency yielded information on changes in the mean particle size.

1-Butanol↗