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PubMed1987

Physiological bases of acoustic LRT in nonstutterers, mild stutterers, and severe stutterers.

The simple reaction time paradigm, incorporating a variable foreperiod, was used to investigate relative contributions of the respiratory and laryngeal systems to mild and severe stutterers' prolonged acoustic laryngeal reaction time (LRT) values. Prephonatory kinematic data were analyzed in terms of frequency of initiation, timing, and organization of events executed to attain the functional physiological targets of respiratory inflation during foreperiods and phonation onset after foreperiods. Acoustic data replicated a previously observed composite stuttering severity and foreperiod effect on stutterers' acoustic LRT values. Kinematic data revealed that, in general, the mild stutterers demonstrated delayed initiation of respiratory events and appropriate organization of respiratory and laryngeal events while the severe stutterers demonstrated delayed initiation of laryngeal events and inappropriate organization of respiratory and laryngeal events. That is, kinematic data both account for group differences in acoustic LRT values as a function of foreperiod and support the notion that differential respiratory and laryngeal deficits underly mild and severe stutterers' prolonged acoustic LRT values.

Adult↗
PubMed2004

Cranial nerve preservation in surgery for large acoustic neuromas.

Facial nerve outcomes and surgical complication rates for other cranial nerves were evaluated retrospectively after the resection of large acoustic neuromas. The charts of all patients who underwent surgical removal of an acoustic neuroma between 1992 and 2001 at New York University Medical Center were reviewed. Fifty-four patients with tumors measuring 3 cm or larger were included in the study. Four patients had neurofibromatosis type 2, two of whom underwent bilateral removal of acoustic neuromas. Translabyrinthine microsurgical removal of tumor was performed in 47 of 56 cases (84%). In all cases, EMG monitoring, improved sharp microdissection, and ultrasonic aspiration were employed. Facial nerve function was assessed using the House-Brackmann facial nerve grading system immediately after surgery and at follow-up visits. A House-Brackmann grade III or better was achieved in 90% of patients, and a grade II or better was achieved in 84% of patients. Ultimate facial nerve outcome was excellent after the surgical resection of large acoustic neuromas. Preoperative cranial nerve palsies also improved after surgery. The translabyrinthine approach for tumor removal is our treatment of choice for acoustic neuromas 3 cm or larger.

Journal Article↗
PubMed1999

Infratentorial approach to internal acoustic meatus.

Surgical exposure of internal acoustic meatus via typical suboccipital retrosigmoid craniotomy is limited by inner ear structures that should remain intact if hearing preservation is attempted. Feasibility of supracerebellar-infratentorial approach to the meatus with more medial angle of exposure and with preservation of inner ear structures was studied on fresh cadavers and on computed tomography pictures of temporal bones. Anatomical relationships of internal acoustic meatus and adjacent structures show marked individual variability. When typical retrosigmoid craniotomy is used to expose meatal fundus, significant medial retraction of cerebellar hemisphere is required in 47% of the patients to avoid opening endolymphatic spaces. Internal acoustic foramen and meatus can be exposed via craniotomy situated under transverse sinus, with 10-15 mm downward retraction of cerebellum. Medial extent of craniotomy can be planned on preoperative imaging studies. Infratentorial supracerebellar exposure of internal acoustic meatus allows for more medial angle of surgical approach than standard retrosigmold craniotomy. It can be used when preoperative imaging studies show that anatomical relationships between internal acoustic meatus and inner ear structures would require excessive cerebellar retraction to visualize a whole tumor inside meatus.

Journal Article↗
PubMed1993

Transient chaos in room acoustics.

The decay of sound in an auditorium due to absorption is central to the theory and practice of room acoustics. Within geometrical acoustics, this problem involves the partial trapping of chaotic ray trajectories in billiards, hence transient chaos. We first present a theoretical and numerical analysis of the decay of rays in 2-D chaotic billiards (2-D room acoustic models) and show that the existence of fluctuations (in the mean-free path and in the rate of phase space exploration) leads to modifications from the standard statistical theory. An ergodic wave theory of room acoustics based on a wave formulation is then discussed and tested by direct numerical calculations of the eigenmodes in 2-D billiards. Finally, we present a semiclassical calculation of the acoustic Green's functions in the time domain, based on a summation over rays, viewed as generalized wave impulses, and successfully compare its predictions with a direct numerical integration of the wave equation. This formalism provides a framework to link the geometrical ray description to the ergodic wave theory.

Journal Article↗
PubMed2001

Caterpillar talk: acoustically mediated territoriality in larval Lepidoptera.

We provide evidence for conspecific acoustic communication in caterpillars. Larvae of the common hook-tip moth, Drepana arcuata (Drepanoidea), defend silk nest sites from conspecifics by using ritualized acoustic displays. Sounds are produced by drumming the mandibles and scraping the mandibles and specialized anal "oars" against the leaf surface. Staged interactions between a resident and intruder resulted in escalated acoustic "duels" that were typically resolved within minutes, but sometimes extended for several hours. Resident caterpillars generally won territorial disputes, regardless of whether they had built the nest, but relatively large intruders occasionally displaced residents from their nests. All evidence is consistent with acoustic signaling serving a territorial function. As with many vertebrates, ritualized signaling appears to allow contestants to resolve contests without physical harm. Comparative evidence indicates that larval acoustic signaling may be widespread throughout the Lepidoptera, meriting consideration as a principal mode of communication for this important group of insects.

Animal Communication↗
PubMed2001

The acoustic cortex in frontal dementia.

Frontal dementia is a clinical entity of cognitive impairment, characterized mostly by progressive loss of fluency in speech, eventually resulting in aphasia or anomia, associated frequently with early loss of insight and many forms of inappropriate behavior. Hyperphosphorylation of the isoforms of tau protein, a microtubule-associated protein, which plays an important role in the pathogenetic mechanisms of Alzheimer's disease, is mainly involved in the pathogenesis of frontal dementia. In the present study, the morphological alterations of the acoustic cortex are described in three cases of dementia who fulfilled all the clinical and neuropathological criteria of frontal dementia. Specimens from the acoustic area of the temporal cortex were processed with Golgi silver impregnation techniques, Cajal and Rio Hortega stainings and electron microscopy. A tremendous loss of Cajal-Retzius neurons in layer I of the acoustic cortex was noticed in Golgi staining, associated with dense reactive astrocytosis, visualized clearly in Cajal gold impregnation technique. Loss of dendritic spines was extensively seen in layers III, V, and VI in correlation with normal controls. The electron microscopy revealed numerous Pick bodies, whose tau protein was the main protein constituent. Paired helical filaments were seen in the perikaryon and the axons of the neurons of layers IV, V, and VI. Synaptic alterations were extensively seen in the acoustic cortex consisting mainly of degeneration of the postsynaptic components. The authors think that the impressive morphological alterations of the acoustic cortex in frontal dementia might explain the early onset of deficiency of communication that most of the patients demonstrate in the initial stage of the disease.

Auditory Cortex↗
PubMed2000

Temporal relation between acoustic and force responses at the adductor pollicis during nondepolarizing neuromuscular block.

BACKGROUND: Contracting muscle emits sounds. The purpose of this study was to compare the time course of muscular paralysis at the adductor pollicis muscle (AP) with use of acoustic myography and mechanomyography. METHODS: Thirteen elective surgery patients, American Society of Anesthesiologists physical status I, received rocuronium (0.6 mg/kg intravenously) as a bolus dose during general anesthesia. Force of AP was measured with use of a strain gauge, and sounds were recorded simultaneously with use of a small condenser microphone fixed on the palmar surface of the hand over the AP. Supramaximal stimulation was applied to the ulnar nerve at 0.1 Hz for 45-60 min. In seven patients, the response to train-of-four stimulation was also recorded during recovery. RESULTS: Force and sounds both were equally sensitive in measuring maximum block. The relation between sound and force was curvilinear, with good agreement near 0 and 100% and acoustic response exceeding mechanical response at intermediate levels of block. The acoustic signal had a slower onset and a faster recovery than the force response. The fade response of sound to train-of-four stimulation also recovered faster than that of force. CONCLUSION: Acoustic myography is an alternative method to monitor muscular paralysis that is easy to set up and applicable to most superficial muscles. However, the time course of relaxation at AP using acoustic myography differs from the time course of force relaxation. Therefore, these two methods are not equivalent when applied to AP.

Adult↗
PubMed1998

Acoustically active lipospheres containing paclitaxel: a new therapeutic ultrasound contrast agent.

RATIONALE AND OBJECTIVES: Paclitaxel-carrying lipospheres (MRX-552) were developed and evaluated as a new ultrasound contrast agent for chemotherapeutic drug delivery. METHODS: Paclitaxel was suspended in soybean oil and added to an aqueous suspension of phospholipids in vials. The headspace of the vials was replaced with perfluorobutane gas; the vials were sealed, and they were agitated at 4200 rpm on a shaking device. The resulting lipospheres containing paclitaxel were studied for concentration, size, acute toxicity in mice, and acoustic activity and drug release with ultrasound. Lipospheres containing sudan black dye were produced to demonstrate the acoustically active liposphere (AAL)-ultrasound release concept. RESULTS: Acoustically active lipospheres containing paclitaxel had a mean particle count of approximately 1 x 10(9) particles per mL and a mean size of 2.9 microns. Acute toxicity studies in mice showed a 10-fold reduction in toxicity for paclitaxel in AALs compared with free paclitaxel. The AALs reflected ultrasound as a contrast agent. Increasing amounts of ultrasound energy selectively ruptured the AALs and released the paclitaxel. CONCLUSIONS: Acoustically active lipospheres represent a new class of acoustically active drug delivery vehicles. Future studies will assess efficacy of AALs for ultrasound-mediated drug delivery.

Animals↗
PubMed2003

Is there a relation between acoustic trauma or noise-induced hearing loss and a subsequent appearance of Ménière's Disease? An epidemiologic study of 17245 cases and a review of the literature.

OBJECTIVE: To explore whether acute acoustic trauma or noise-induced hearing loss may cause the later development of Ménière's Disease. STUDY DESIGN: Retrospective search of a military medical data bank. SETTING: Medical records of 17245 Israel Defense Force veterans who were recognized as being disabled as a result of acoustic trauma or noise-induced hearing loss. PATIENTS: Eleven cases of late-onset Ménière's Disease were retrieved from these files. MAIN OUTCOME MEASURES: Documented symptoms and audiograms. RESULTS: Eleven of the 17425 veterans appeared to have typical Ménière's Disease. Their symptoms included attacks of vertigo, lasting between half an hour and a few hours and no more than 24 hours; the sensation of aural fullness; and tinnitus accompanied by a fluctuating or permanent low-tone hearing loss. Four of the 11 patients had a documented previous noise-induced hearing loss, and the remaining 7 had experienced acute acoustic trauma. The Ménière's Disease was bilateral in three cases. The average period between the first documented hearing loss and the onset of Ménière's Disease was 15.8 years (standard deviation, +/- 6.6 years). This yielded a prevalence of 1.9:100000 of Ménière's Disease in a population with acoustic trauma or noise-induced hearing loss-a figure comparable to that in the general population. CONCLUSIONS: No support was found for the hypothesis that Ménière's Disease may be causally related to previous acoustic trauma or noise-induced hearing loss.

Adolescent↗
PubMed2003

Inverse scattering theory: renormalization of the Lippmann-Schwinger equation for acoustic scattering in one dimension.

The most robust treatment of the inverse acoustic scattering problem is based on the reversion of the Born-Neumann series solution of the Lippmann-Schwinger equation. An important issue for this approach to inversion is the radius of convergence of the Born-Neumann series for Fredholm integral kernels, and especially for acoustic scattering for which the interaction depends on the square of the frequency. By contrast, it is well known that the Born-Neumann series for the Volterra integral equations in quantum scattering are absolutely convergent, independent of the strength of the coupling characterizing the interaction. The transformation of the Lippmann-Schwinger equation from a Fredholm to a Volterra structure by renormalization has been considered previously for quantum scattering calculations and electromagnetic scattering. In this paper, we employ the renormalization technique to obtain a Volterra equation framework for the inverse acoustic scattering series, proving that this series also converges absolutely in the entire complex plane of coupling constant and frequency values. The present results are for acoustic scattering in one dimension, but the method is general. The approach is illustrated by applications to two simple one-dimensional models for acoustic scattering.

Journal Article↗
PubMed2005

Synthesis and analysis of linear and nonlinear acoustical vortices.

Acoustical screw dislocations are synthesized in various configurations with a versatile experimental setup. The experimental setup is based on the inverse filter technique and allows one to synthesize one or more acoustical vortices with a chosen width, position, and topological charge. An interesting feature of this experimental facility to study screw dislocation behavior is the direct measurement in amplitude and phase. This characteristic is used to develop an original method of decomposition of an acoustical vortex field in order to analyze the acoustical vortices. Moreover, the behaviors of two acoustical vortices of the same or opposite charge have been studied experimentally and compared to theoretical laws.

Journal Article↗
PubMed2006

Modes of nonlinear acoustic transparency in the strained paramagnetic crystal.

The propagation of transverse-longitudinal acoustic pulses through a strained cubic crystal containing resonant paramagnetic impurities with effective spin S =1 is investigated. It is supposed that the pulses propagate under arbitrary angle with respect to the direction of the external static deformation parallel to the fourth-order symmetry axis. In this geometry, both the transverse and longitudinal components of the acoustic field have high-frequency and zero-frequency spectral components. We show that a pulse can propagate in modes different from the acoustic self-induced transparency. In particular, a pulse propagating in the mode of an acoustic self-induced supertransparency substantially changes the populations of the spin sublevels, but its group velocity remains almost equal to the linear velocity of the sound. If a pulse propagates in the acoustic extraordinary transparency mode, then its group velocity is substantially lower while the sublevel populations remain virtually invariant. Also, the modes of propagation under conditions of weakly excited spin transitions and large detuning of the pulse high-frequency components are identified.

Journal Article↗
PubMed2001

Acoustically induced stark effect for excitons in intrinsic semiconductors.

A Stark effect for excitons parametrically driven by coherent acoustic phonons is proposed. Our scheme refers to a low-temperature intrinsic semiconductor or semiconductor nanostructure pumped by an acoustic wave (frequency band nu(ac) approximately equal to 1-40 GHz and intensity range I(ac) approximately equal to 10(-2)-10(2) W/cm(2)) and probed by low-intensity light. Tunable optical band gaps, which strongly change the spectral shape of the exciton line, are induced in the polariton spectrum by acoustic pumping. We develop an exactly solvable model of the acoustic Stark effect and apply our results to GaAs driven by bulk or surface acoustic waves.

Journal Article↗
PubMed2004

Probing acoustic fields of clinically relevant transducers: the effect of hydrophone probes' finite apertures and bandwidths.

The influence of finite aperture and frequency response of piezoelectric ultrasonic hydrophone probes on the free-field pulse intensity integral (PII) and mechanical index (MI) was investigated using a comprehensive acoustic wave propagation model. The model developed was capable of predicting the true pressure-time waveforms at virtually any point in the field. The input to the model used pressure amplitude data measured in the immediate vicinity of the acoustic source or transducer considered. The experimental verification of the model was obtained using a commercially available, 8 MHz, dynamically focused linear array and a single element, 5 MHz, focused rectangular source. The verification was performed at low and high excitation levels, corresponding to linear and nonlinear acoustic wave propagation, respectively. The pressure-time waveforms were recorded using piezoelectric polymer hydrophone probes that had different sensitivities, frequency responses, bandwidths, and active element diameters. The nominal diameters of the probes ranged from 50 to 500 microm, and their useable bandwidths varied between 55 and 100 MHz. The PII, used to calculate the thermal index (TI), was found to increase with increasing bandwidth and decreasing effective aperture of the probes. The MI, another safety indicator, also was affected, but to a lesser extent. The corrections predicted using the model were used to reduce discrepancies as large as 30% in the determination of PII. The results of this work indicate that, by accounting for hydrophones' finite aperture and correcting the value of PII, all intensities derived from the PII can be corrected for spatial averaging error. The results also point out that caution should be exercised when comparing acoustic output data. In particular, hydrophone's frequency characteristics of the effective diameter and sensitivity are needed to correctly determine the MI, TI, and the total acoustic output power produced by an imaging transducer.

Algorithms↗
PubMed2004

Performance of piezoelectric fiber-reinforced composites for active structural-acoustic control of laminated composite plates.

This paper deals with the active structural acoustic control of thin laminated composite plates using piezoelectric fiber-reinforced composite (PFRC) material for the constraining layer of active constrained layer damping (ACLD) treatment. A finite element model is developed for the laminated composite plates integrated with the patches of ACLD treatment to describe the coupled structural-acoustic behavior of the plates enclosing an acoustic cavity. The performance of the PFRC layers of the patches has been investigated for active control of sound radiated from thin symmetric and antisymmetric cross-ply and antisymmetric angle-ply laminated composite plates into the acoustic cavity. The significant effect of variation of piezoelectric fiber orientation in the PFRC layer on controlling the structure-borne sound radiated from thin laminated plates has been investigated to determine the fiber angle in the PFRC layer for which the structural-acoustic control authority of the patches becomes maximum.

Journal Article↗
PubMed2006

New method of change in temperature coefficient delay of acoustic waves in thin piezoelectric plates.

As is well-known, the development of high-effective and thermostable acoustic devices assumes using the acoustic waves with high coefficient of electromechanical coupling (K2) and low temperature coefficient of delay (TCD). At present, it also is well-known that fundamental shear horizontal (SH0) acoustic waves in thin piezoelectric plates possess by significantly more electromechanical coupling compared to surface acoustic waves (SAW) in the same material. However, although the value of TCD of SH0 waves is insignificantly less than for SAW, this is not enough for development of thermostable devices. This paper suggests a new way of decreasing TCD of SH0 waves in piezoelectric plates at a high level of electromechanical coupling. This way assumes to use the structure containing the piezoelectric plate and liquid with the special dependence of permittivity on temperature. Theoretical and experimental investigation showed that, for SH0 wave in YX LiNbO3 plate at hf = 700 m/s (h = plate thickness, f = wave frequency) the presence of butyl acetate can decrease the value of TCD by six times at K2 = 30%. In a whole the obtained results open the wide prospect of using SH0 wave in thin piezoelectric plate for development of high effective and thermo-stable acoustic devices.

Journal Article↗
PubMed1991

Scanning acoustic microscopy of neoplastic and inflammatory cutaneous tissue specimens.

Acoustic microscopy utilizes high frequency ultrasound to generate microscopic images. The current study was designed to examine representative disorders of the skin by use of a reflective scanning acoustic microscope (R-SAM), and to determine whether the obtainable resolution was sufficient to render a microscopic diagnosis. An Olympus UH3 Scanning Acoustic Microscope was utilized with lenses producing burst wave frequencies at 600 and 800 MHz (600 and 800 million cylces/sec). Cutaneous tissue specimens representing 12 different neoplastic and inflammatory disorders were examined. Acoustic images of unstained sections were compared with conventional light microscopic study of sections stained with hematoxylin-eosin. In most neoplasms examined, it was possible to make a specific diagnosis primarily from low magnification pattern analysis. Although individual cells could be visualized, cytologic atypia was poorly defined. In the inflammatory disorders, a specific diagnosis was possible in all but bullous pemphigoid and lichen planus, because the composition of the inflammatory infiltrate was difficult to determine. The advantages of the R-SAM include the capability of producing an acoustic profile of the tissue and the future possibility of in situ diagnosis.

Humans↗
PubMed2003

Sexual selection in female perceptual space: how female túngara frogs perceive and respond to complex population variation in acoustic mating signals.

Female preferences for male mating signals are often evaluated on single parameters in isolation or small suites of characters. Most signals, however, are composites of many individual parameters. In this study we quantified multivariate traits in the advertisement call of the túngara frog, Physalaemus pustulosus. We represented the calls in multidimensional scaling space and chose nine test calls to represent the range of population variation. We then tested females for phonotactic preference between calls in each pair of the nine test calls. We used statistics developed for paired comparisons in such "round robin" competitions to evaluate the null hypothesis of equal attractiveness, and to examine the degree to which females responded to calls as being different from or similar to one another in attractiveness. We then examined the attractiveness of each test call relative to all other test calls as a function of their location in multivariate acoustic space (the acoustic landscape) to visualize sexual selection on calls. Finally, we used methods from cognitive psychology to illustrate the females' perception of call attractiveness in multivariate space, and compared this perceptual landscape to the acoustic landscape of quantitative call variation. We show that correlations between individual call characters are not strong and thus there are few biomechanical constraints on their independent evolution. Most call variables differed among males, and there was high repeatability of call characters within males. Females often discriminated between pairs of calls from the population, and there were significant differences among calls in their attractiveness. Female preferences for calls were not stabilizing. The region of the acoustic landscape that was most attractive to females included the mean call but was not centered around it. The females' perceptual or preference landscape did not correlate with the call's acoustic landscape, and female perception of calls decreased rather than enhanced call differences.

Animal Communication↗