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PubMed1989

Effects of alcohol on the acoustic-phonetic properties of speech: perceptual and acoustic analyses.

This report summarizes the results of a series of studies that examined the effects of alcohol on the acoustic-phonetic properties of speech. Audio recordings were made of male talkers producing lists of sentences under a sober condition and an intoxicated condition. These speech samples were then subjected to perceptual and acoustic analyses. In one perceptual experiment, listeners heard matched pairs of sentences from four talkers and were required to identify the sentence that was produced while the talker was intoxicated. In a second perceptual experiment, Indiana State Troopers and college undergraduates were required to judge whether individual sentences presented in isolation were produced in a sober or an intoxicated condition. The results of the perceptual experiments indicated that groups of listeners can significantly discriminate between speech samples produced under sober and intoxicated conditions. For acoustic analyses, digital signal processing techniques were used to measure acoustic-phonetic changes that took place in speech production when the talker was intoxicated. The results of the acoustical analyses revealed consistent and well-defined changes in speech articulation between sober and intoxicated conditions. Because speech production requires fine motor control and timing of the articulators, it may be possible to use acoustic-phonetic measures as sensitive indices of sensory-motor impairment due to alcohol consumption.

Adult↗
PubMed2003

A state feedback electro-acoustic transducer for active control of acoustic impedance.

In this paper, a new control system in which the acoustic impedance of an electro-acoustic transducer diaphragm can be actively varied by modifying design parameters is presented and its effectiveness is theoretically investigated. The proposed control system is based on a state-space description of the control system derived from an electrical equivalent circuit of an electro-acoustic transducer to which a differentiating circuit is connected, and is designed using modem control theory. The optimal quadratic regulator is used in the control system design, with its quadratic performance index formulated for producing desired acoustic impedance. Computer simulations indicate that the acoustic impedance of the diaphragm can be significantly varied over a wide frequency range that includes the range below the resonance frequency of the electro-acoustic transducer. A computer model of the proposed control system is used to illustrate its application to semi-active noise control in a duct. It is demonstrated that the proposed control system provides substantial reductions in the noise radiating from the outlet of the duct, both in the stiffness control range and in the mass control range.

Journal Article↗
PubMed2000

Effects of acoustic trauma on acoustic enhancement of electrically evoked otoacoustic emissions.

Moderate acoustic trauma results in decreased cochlear sensitivity and frequency selectivity. This decrease is believed to be caused by damage to the cochlear amplifier that is associated with outer hair cells (OHCs) and their nonlinear electromechanical characteristics. A consequence of OHC nonlinearity is the acoustic enhancement effect, in which low-frequency electrically evoked otoacoustic emissions are enhanced by a simultaneous tone. The present study found that acoustic trauma reduced the acoustic enhancement effect and this reduction is correlated with the N1 threshold at the electrode site. This result is consistent with the theory that trauma affects the mechanoelectric transduction process, thus affecting cochlear mechanical nonlinearity. Acoustic trauma also reduced the cochlear microphonic in a way that suggests that the number of functioning tension-gated channels and the stiffness of the gating springs were decreased. In some cases, the electromechanical transduction process was also found to be affected by acoustic trauma.

Animals↗
PubMed1994

The acoustic properties of normal and imbedded bovine bone as measured by acoustic microscopy.

The acoustic impedance of bovine femoral cortical bone was measured with a scanning acoustic microscope used in the reflection mode. The bone was measured in the unimbedded state and after plastic imbedding. The acoustic impedance of the unimbedded specimens was also measured with a standard transmission ultrasonic technique. For the unimbedded bovine specimens there was a good correlation between the bulk transmission impedance and the reflection surface impedance (r2 = 0.976) and the values were 9.32 and 9.29 MRayls, respectively. Plastic imbedding produced a consistent and statistically significant increase in the acoustic impedance of the bone (9.71 MRayls). This experiment verified the use of acoustic microscopy as a quantitative materials analysis technique and it demonstrated the potential for material property analysis of imbedded bone.

Acoustic Impedance Tests↗
PubMed1995

Changes in the acoustic startle response and prepulse inhibition of acoustic startle in rats after local injection of pertussis toxin into the ventral tegmental area.

The effect of local injection of pertussis toxin (PTX) into the ventral tegmental area (VTA) on acoustic startle in rats was investigated. The PTX treatment caused only minor effects of its own on the acoustic startle response (ASR) or prepulse inhibition (PPI) of acoustic startle. However, systemic treatment with the indirect DA receptor agonist, amphetamine (2 mg/kg, SC) caused a significant increase in ASR magnitude and a significant disruption of PPI in PTX-treated rats while no such effects were observed in sham-treated rats. Treatment with the direct DA receptor agonist, apomorphine (2 mg/kg, SC), caused a significant disruption of PPI, an effect that was observed in both PTX- and sham-treated rats. Treatment with the 5-HT1A receptor agonist, 8-OH-DPAT (0.5 mg/kg, SC), did not affect PPI in either group but caused a marked increase in ASR magnitude in sham-treated rats. Interestingly, this effect was blocked in PTX-treated rats. The present results suggest that local injection of PTX into the VTA causes an increased sensitivity to the behavioural effects of psychostimulants on acoustic startle and may also suggest that intact midbrain 5-HT1A receptors are essential for the effect of 5-HT1A agonists on acoustic startle.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1998

Evaluation of acoustic properties of the live human smooth-muscle cell using scanning acoustic microscopy.

This study was performed to measure the acoustic propagation speed in live human aortic smooth-muscle cells (HASMC), using scanning acoustic microscopy (SAM) and a novel measurement theory that permits the measurement of the acoustic propagation speed in biological samples of unknown thickness. C-mode and X-Z-mode images of HASMC under three different conditions: growing (G); differential (D); and on hypotonic loading (H), were acquired using 100-MHz, 450-MHz and 600-MHz ultrasound. The images exhibit features related to the cell surface curvature and intracellular structure. The theory supporting the methodology is derived in this article and makes use of the interference fringes within the focusing lens of the high-frequency transducer. The propagation speed in the cells was calculated from the location of the interference fringe on the C-mode images and the fringe shift on the X-Y-mode images with 450-MHz ultrasound. The propagation speed in D (1624 +/- 16 m/s) was significantly higher than those in G (1571 +/- 14 m/s, p < 0.05) and H (1585 +/- 8 m/s, p < 0.05). Scanning acoustic microscope measurements, along with the described theory, are useful for studying the acoustic properties of live cells ex vivo and have applications in both pathophysiology and biomechanics.

Acoustics↗
PubMed2002

Acoustic phenotypes for speech-genetics studies: toward an acoustic marker for residual /s/ distortions.

Findings in a prior study series indicate that acoustic markers may have the requisite sensitivity and specificity to discriminate speakers with histories of several types of speech disorders, one of which is posited to be genetically inherited. The present study in this series compares acoustic data from three groups of adolescent speakers. Group 1 speakers had residual dentalized /s/ distortions in conversational speech and histories of significant age-inappropriate deletion and substitution errors. Group 2 speakers also had residual dentalized /s/ distortions in conversational speech, but their speech histories were limited to dentalized distortions of /s/ and other fricatives/affricates. Group 3 speakers had typical speech on assessment and no histories of speech errors. Owing to the limited number of perceptually dentalized /s/ tokens produced by Groups 1 and 2 speakers in a phrase-level speech task, acoustic analyses were completed on /s/ tokens transcribed as correct for speakers in all groups. Moments analyses of /s/ spectra in three words with /s/-initial clusters yielded statistically significant differences and consistent trends for mean spectral frequency and spectral variance for Group 1 compared with Group 2 speakers. These findings for perceptually normal /s/ tokens are interpreted as additional support for the potential of acoustic markers to discriminate speakers' speech-error histories. The discussion considers possible developmental and normalization correlates of the acoustic findings for speakers with each of the two types of speech-error histories studied in this paper.

Adolescent↗
PubMed1989

Acoustic rhinometry: evaluation of nasal cavity geometry by acoustic reflection.

To study the geometry of the nasal cavity we applied an acoustic method (J. Appl. Physiol. 43: 523-536, 1977) providing an estimate of cross-sectional area as a function of distance. Acoustic areas in a model constructed from a human nasal cast, in the nasal cavity of a cadaver and in 10 normal subjects and two patients with well-defined afflictions of the nasal cavity, were compared with similar areas obtained by computerized tomography (CT) scans, a specially developed water displacement method, and anterior rhinomanometry. We found a coefficient of variation of the areas of less than 2% by the acoustic method compared with 15% for the rhinomanometric measurements. Acoustic areas correlated highly to similar areas obtained by CT scanning (r = 0.94) and by water displacement (r = 0.96). In two patients the acoustic method accurately outlined, respectively, a tumor in the nose and a septum deviation. It is concluded that this method provides an accurate method for measuring the geometry of the nasal cavity. It is easy to perform and is potentially useful for investigation of physiological and pathological changes in the nose.

Acoustics↗
PubMedDate not supplied

[Acoustically guided behavior in the early ontogeny of the long-eared owl: the characteristics of its feeding behavior and the parameters of the acoustic signal important for its stimulation].

Feeding behaviour of nestlings of long-eared owls (Asio otus) is manifested as a complex of two components, i. e., the vocal reaction (uttering of begging calls) and specific motor response. Exposure to the appropriate acoustic signals resulted in an increase in the number of begging calls and approaching reaction to the source of acoustic signals. The range of monotonal signals effective for eliciting feeding behaviour was 0.2--1.5 kHz, the most effective were the tones of 0.3--0.7 kHz. The approaching reaction to acoustic signals was rather weak up to the 5th day after hatching, clearly pronounced in the 6--11th days, and later on was abruptly substituted for the response of following the visual stimulus provoked by the acoustic stimulation. Specific acoustic afferentation is the sole stimulus for begging in nestlings up to 11 days of age, and it remains a triggering stimulus for feeding behaviour in owl nestlings throughout the period of artificial feeding under laboratory conditions (up to the 40th day after hatching.

Acoustic Stimulation↗
PubMed1979

Factors influencing the acoustic-immittance characteristics of the acoustic reflex.

Measurements of the aural acoustic-immittance (admittance and impedance) characteristics of the middle-ear transmission system in humans during the quiescent (static) and reflexive states were made (N = 36) utilizing a signal-averaging technique. Three pure tones (750, 1000, and 2000 Hz) and broadband noise stimuli elicited the acoustic reflex in 2-dB steps at sound-pressure levels from 84-116 dB (tones) and 66-116 dB (noise) during ascending- and descending-intensity level runs. The contralateral middle-ear activity was monitored with a 220-Hz probe by digitizing the conductance and susceptance outputs of an admittance meter. A computer corrected for the ear-canal volume utilizing measurements made at ear-canal pressures of 0 and --350 daPa and then converted the conductance and susceptance values into admittance and impedance units. The results were reported in absolute and relative immittance units, including components, as a function of both stimulus sound-pressure level and intensity level above the acoustic-reflex threshold. The static immittance of the middle ear changed nonlinearly over time to lower admittance or higher impedance values. The influence of this static-immittance shift on the reflex magnitude was discussed. The largest mean reflex magnitude and the slowest rate of growth were observed with broadband noise, although eight of the 36 subjects demonstrated the largest reflex magnitude in response to one or more of the tonal stimuli. Although static-immittance values and acoustic-reflex thresholds were poorly correlated, the reflex magnitudes were proportional to static immittance. The variability of the reflex measures was similar to the variability of the static-immittance values. Finally, bi-directional changes in resistance during the reflexive state were observed and discussed.

Acoustic Impedance Tests↗
PubMed1999

Acoustic reflex detection using wide-band acoustic reflectance, admittance, and power measurements.

The measurement of the acoustic reflex threshold is a basic component of the diagnostic audiological test battery that may subject patients to potentially harmful sound pressures. A wide-band acoustic impedance and reflectance system (D. H. Keefe, R. Ling, & J. C. Bulen, 1992) was investigated as a means of obtaining reflex thresholds at a reduced level and as a means of providing a more complete characterization of the reflex than current clinical methods provide. Reflex thresholds obtained by measuring changes in wide-band admittance, reflectance, and power were at least 8 dB lower than those obtained with the standard clinical technique. These reflex-induced changes were accounted for by a simple oscillator model of the middle ear, assuming that the acoustic reflex results in an increase in stiffness. The results support further investigation of reflectance-based measures of the acoustic reflex as a clinical tool and as a means of studying the reflex mechanism.

Acoustic Impedance Tests↗
PubMed2002

Influence of acoustic impedance of multilayer acoustic systems on the transfer function of ultrasonic airborne transducers.

In different solutions of ultrasonic transducers radiating acoustic energy into the air there occurs the problem of the proper selection of the acoustic impedance of one or more matching layers. The goal of this work was a computer analysis of the influence of acoustic impedance on the transfer function of piezoceramic transducers equipped with matching layers. Cases of resonance and non-resonance matching impedance in relation to the transfer function and the energy transmission coefficient for solid state-air systems were analysed. With stable thickness of matching layers the required shape of the transfer function can be obtained through proper choice of acoustic impedance were built (e.g. maximal flat function). The proper choice of acoustic impedance requires an elaboration of precise methods of synthesis of matching systems. Using the known matching criteria (Chebyshev's, DeSilets', Souquet's), the transfer function characteristics of transducers equipped with one, two, and three matching layers as well as the optimisation methods of the energy transmission coefficient were presented. The influence of the backside load of the transducer on the shape of transfer function was also analysed. The calculation results of this function for different loads of the transducer backside without and with the different matching layers were presented. The proper load selection allows us to obtain the desired shape of the transfer function, which determines the pulse shape generated by the transducer.

Journal Article↗
PubMed2003

Redshift of acoustic waves in acoustic streaming.

Redshift, namely, the frequency decline in the frequency spectrum of an acoustic wave in water, was observed by measuring the frequency spectrum of acoustic streaming in a standing wave field. We desire that relations of the energy epsilon and momentum mu of acoustic waves analogous to those under quantum conditions hold, that is, epsilon =n(p)h(omega), mu=n(p)h(k), where h=h/2pi (h is Planck's constant), n(p) is the phonon density, omega is the angular frequency, and k is the wave number. In this case, a redshift indicates that acoustic waves suffer energy loss or annihilation of phonons. We show that the driving force of streaming is derived from the momentum transfer of phonons and the direct conversion of energy from acoustic energy to kinetic energy of the medium.

Journal Article↗
PubMedDate not supplied

Cerebellopontine angle tumours, other than acoustic neuromas. A report on 34 cases. A presentation of 7 bilateral acoustic neuromas.

The symptoms, preoperative diagnostic results and histological findings in 34 cerebellopontine angle tumour cases, other than acoustic neuromas, are presented. The meningeomas dominate by far this group of tumours. The symptomatology is much less uniform than that of the acoustic neuromas, where the VIII nerve is dominant. The facial nerve is less involved, whereas the other cranial nerves give symptoms more frequently. One remarkable sign is the presence of severe trigeminal neuralgia, which we have not encountered in acoustic neuromas. Only 35% of the 'non-neuroma' patients had elevated spinal fluid protein, compared with 100% in our acoustic neuroma cases. Furthermore, 7 patients with bilateral acoustic neuromas are presented. The connection with von Recklinghausens disease and multiple meningeomas is discussed.

Adult↗
PubMed1999

Interaction between acoustic and electric sensitization of the acoustic startle response in rats.

Sensitization is the general increase of responsiveness observed after aversive stimulation. Usually footshocks are used as aversive stimuli. According to the 'Dual Process Theory' by Groves and Thompson. Psychol. Rev. 1970;77:419-450, not only additional aversive stimuli but also the response-eliciting stimuli themselves have a sensitizing effect, the degree of sensitization depending upon the stimulus intensity. We tested this suggestion in the footshock sensitization paradigm of the acoustic startle response (ASR): (1) High SPL (sound pressure level) acoustic stimuli (119 dB SPL) presented instead of footshocks also elicited strong sensitization. (2) While footshocks presented after startle stimuli with low SPL (95 dB) were able to produce a strong further sensitization of the ASR, footshocks presented after startle stimuli with high SPL (110 dB) only caused a minor sensitization of the ASR. (3) Diazepam (3 mg/kg i.p.) decreased ASR to high SPL (115 dB) stimuli. In this case footshocks elicited significant sensitization of the ASR despite intense startle stimuli. The present results support the 'Dual Process Theory'. Furthermore we could show that acoustic and footshock sensitization interact. We therefore suggest that both, acoustic and footshock sensitization, are mediated partly via the same neural circuitry.

Acoustic Stimulation↗
PubMed1982

Reexamination of acoustic evidence in the Kennedy assassination. Committee on Ballistic Acoustics, National Research Council.

Sounds recorded in Dallas at the time of the assassination of John F. Kennedy were analyzed by two research groups, whose reports formed the basis for the opinion that two gunmen fired at President Kennedy. These reports and the acoustic evidence have been studied by the Committee on Ballistic Acoustics, and further acoustic analyses, including sound spectrograms, have been performed. The committee finds that the acoustic data do not support a conclusion that a second gunman was involved in the assassination.

Acoustics↗
PubMed1983

[Acoustic inner ear trauma by impedance measurement. Acute acoustic trauma?].

We report on two patients with sudden hearing loss occurring immediately after registration of an acoustically elicited acoustic reflex with pure tones of 500, 1000, 2000, and 4000 cps and 125 dB HL. Aetiology and patho-physiology of this form of acute acoustic trauma are discussed. An obvious destruction of middle ear structures or the membrane of the round and oval window can be excluded. Assuming pre-existing disposition, e.g. distortion of microcirculation in the cochlea, the acoustic stimulus is merely the trigger for the imminent sudden hearing loss. Therefore, we suggest to limit the stimulus power to 105 dB HL. In every case one should keep in mind the possible danger of this examination and perform a benefit-risk calculation in every patient.

Acoustic Impedance Tests↗
PubMed1995

Acoustics in educational settings. Subcommittee on Acoustics in Educational Settings of the Bioacoustics Standards and Noise Standards Committee American Speech-Language-Hearing Association.

The Americans with Disabilities Act (enacted July 26, 1990) has brought into focus the need for removing barriers and improving accessibility of all buildings and facilities. It is clear that the definition of barrier must be expanded to include not only structural features that limit physical accessibility, but also acoustical barriers that limit access to communication and information. Acoustical interference caused by inappropriate levels of background noise and reverberation presents a barrier to learning and communication in educational settings and school-sponsored extracurricular activities, particularly for students with hearing loss or other language/learning concerns. ASHA has provided these guidelines and acoustical improvement strategies in order to assist communication-related professionals, teachers, school officials, architects, contractors, state education agencies, and others in developing the best possible learning environment for all students. Additional research on both the acoustical characteristics of learning environments and the communication requirements of learners is encouraged.

Acoustics↗