Showing papers in "Acoustics Research Letters Online-arlo in 2003"
TL;DR: A computer model (expectation maximization of a mixture of Gaussians) is used to learn the positions of vowel categories from two sets of recorded words, and results show that vowel positions learned on the basis of infant-directed (ID) speech correspond better to those in the input than those learned onThe basis of adult- directed (AD) speech.
Abstract: A computer model (expectation maximization of a mixture of Gaussians) is used to learn the positions of vowel categories from two sets of recorded words. The number of vowels is known beforehand. The results show that vowel positions learned on the basis of infant-directed (ID) speech correspond better to those in the input than those learned on the basis of adult-directed (AD) speech.
142 citations
TL;DR: In this article, the lesions generated by high intensity ultrasound were studied in transparent tissue phantoms premixed with and without ultrasound contrast agents (UCA) at 1.1-and 3.5-MHz acoustic waves.
Abstract: The lesions generated by high intensity ultrasound were studied in transparent tissue phantoms premixed with and without ultrasound contrast agents (UCA) at 1.1- and 3.5-MHz acoustic waves. Generation of small bubbles was observed at the very beginning of exposure, whereas cigar-shaped thermal lesions began to form at the focus after a delay. After further heating, boiling occurred and changed the lesion to tadpole-shape, with advancement toward the transducer. Broadband noise was detected in phantoms with UCA initially. UCA also lowered the pressure threshold and enlarged the lesion. Although thermal and cavitation effects are believed to be both important in lesion formation, tadpole-shaped transformation results from boiling activity.
79 citations
TL;DR: This study demonstrates that freely swimming, American shad show a variety of behaviors in response to pure tone, ultrasonic stimulation, which depends primarily on stimulus amplitude and, to a lesser degree, on stimulus frequency, direction and duration.
Abstract: Many species of odontocete cetaceans (toothed whales) use high frequency clicks (60–170 kHz) to identify objects in their environment, including potential prey. Behavior and physiological studies have shown that American shad, Alosa sapidissima, can detect ultrasonic signals to at least 180 kHz. This study demonstrates that freely swimming, American shad show a variety of behaviors in response to pure tone, ultrasonic stimulation. This response depends primarily on stimulus amplitude and, to a lesser degree, on stimulus frequency, direction and duration.
50 citations
TL;DR: Filter properties and computational cost are compared and results show that filters designed with the base-band impulse invariant transformation give the best overall approximation of the analog properties with reasonable computational cost.
Abstract: Digital implementations of linear gammatone filters are regularly part of auditory models and can be used in the sound processing in cochlear implants. How close digital impulse, magnitude, and phase responses match the corresponding properties of the analog gammatone filter is evaluated for one, finite-impulse response filter design, and for five, infinite-impulse response filter designs: base-band impulse invariant transformation, impulse invariant transformation, matched z transformation, bilinear transformation, and mapping of differentials with backward differences. Filter properties and computational cost are compared as a function of the filter’s order and center frequency, and sampling frequency. Results show that filters designed with the base-band impulse invariant transformation give the best overall approximation of the analog properties with reasonable computational cost.
35 citations
TL;DR: In this article, the effectiveness of these devices was concluded based on the comparison of the acoustical attributes of the devices to deer hearing thresholds and acoustic behavior and concluded that the best frequency range of hearing for whitetail deer appears to be between 2 and 6 kHz.
Abstract: Whitetail deer (Odocileus virginianus) are common across much of the United States. In areas where deer populations are prevalent, there is a propensity for interactions with automobiles. Various methods have been suggested for reducing the number of automobile-deer collisions, including acoustic devices such as deer whistles. Six different whistles were tested in the laboratory and on motor vehicles. Frequencies and intensities generated by the devices when mounted on vehicles at speeds from 30–45 miles per hour were determined. The primary frequency of operation of the closed end whistles on vehicles was determined to be approximately 3.3 kHz with little variation with changes in air pressure. Open-end whistles had a primary frequency of about 12 kHz, with significant variation with changes in air pressure. The best frequency range of hearing for whitetail deer appears to be between 2 and 6 kHz. The effectiveness of these devices was concluded based on the comparison of the acoustical attributes of the devices to deer hearing thresholds and acoustic behavior.
32 citations
TL;DR: In this paper, the statistical properties of acoustic emission signals for tool condition monitoring (TCM) applications in mechanical lathe machining are analyzed, and the analysis of these also reveals discriminating age-related features.
Abstract: The statistical properties of acoustic emission signals for tool condition monitoring (TCM) applications in mechanical lathe machining are analyzed in this paper. Time series data and root mean square (RMS) values at various tool wear levels are shown to exhibit features that can be put into relation with aging in both cases. In particular, the histograms of raw data show power-law distributions above a cross-over value, in which newer cutting tools exhibit more numerous larger events compared with more worn-out ones. For practical purposes, statistics based on RMS values are more feasible, and the analysis of these also reveals discriminating age-related features. The assumption that experimental RMS histograms follow a Beta (β) distribution has also been tested. The residuals of the modeling β functions indicate that the search for a more appropriate fitting function for the experimental distribution is desirable.
26 citations
TL;DR: Listeners with normal hearing identified lowpass and highpass sentences at a range of presentation levels to determine whether rollover effects might be greater in either region, suggesting cochlear processing shows greater level dependence in basal regions tuned to high frequencies than apical, low-frequency regions.
Abstract: Speech recognition accuracy decreases when presentation levels are raised above moderate levels. This “rollover” effect at high levels has generally been viewed as a broadband phenomenon, influencing low- and high-frequency processing similarly. In the current study, listeners with normal hearing identified lowpass and highpass sentences at a range of presentation levels to determine whether rollover effects might be greater in either region. Recognition scores showed larger and more consistent decreases at high levels (i.e., greater rollover) for high-frequency speech materials. The results are consistent with both physiological and psychoacoustic data suggesting that cochlear processing shows greater level dependence in basal regions tuned to high frequencies than apical, low-frequency regions. Predictions of speech intelligibility by methods such as the Speech Intelligibility Index [ANSI, 1997] may be improved if the frequency-dependence of rollover is considered.
26 citations
TL;DR: It is conjecture that the bandwidth of stapes vibration velocity in humans will eventually be shown to exceed thewidth of the audiogram, in line with findings in other amniotic vertebrates.
Abstract: Postmortem and in vivo vibration responses to sound of the stapes and the umbo of human ears are surveyed. The magnitudes of umbo velocity responses recorded postmortem decay between 1 and 5 or 10 kHz at rates between 0 and −3 dB/octave. In contrast, the magnitudes of in vivo umbo vibration are relatively invariant over a wide frequency range, amply exceeding the bandwidth of the audiogram according to one report. Similarly, most studies of postmortem stapes vibration report velocities tuned to about 1 kHz, with magnitudes that decay at a rate of about −6 dB/octave at higher frequencies. In contrast, in vivo stapes responses are apparently only mildly tuned. We conjecture that the bandwidth of stapes vibration velocity in humans will eventually be shown to exceed the bandwidth of the audiogram, in line with findings in other amniotic vertebrates.
24 citations
TL;DR: A visualization technique for image source method including diffraction is presented in this paper, where first-order diffraction in a stage-house, and second-order Diffraction around a loudspeaker enclosure are visualized.
Abstract: The acoustics of a room can be visualized by plotting image sources at the positions where they occur. Recently, the image-source method has been extended to include edge diffraction. A visualization technique for image source method including diffraction is presented. As examples, first-order diffraction in a stage-house, and second-order diffraction around a loudspeaker enclosure are visualized.
20 citations
TL;DR: In this article, sound pulses were projected into the forehead of a neonate, female sperm whale that died following a stranding and attempts to revive it, and two hydrophones, held against the skin, recorded the sound pulses and their reflections.
Abstract: Sound pulses were projected into the forehead of a neonate, female sperm whale that died following a stranding and attempts to revive it. Two hydrophones, held against the skin, recorded the sound pulses and their reflections. A consistent reflection was found about 0.8 ms after sound projection. This time corresponded to the expected two-way travel time back and forth within the spermaceti organ. Reflections were also detected at the frontal surface of the junk from sounds projected into the distal sac area. These signals must have traversed rearward along the axis of the spermaceti organ to the frontal sac where they were likely reflected and directed forward to the front of the junk, demonstrating an acoustic continuum between the spermaceti organ and the junk. These results support the basic Norris and Harvey (1972) theory of sound generation in sperm whales and later amendments to that theory (Mohl and Amundin (1991), Mohl (2001)).
19 citations
TL;DR: In this article, simultaneous modal and acoustical measurements on three violins characterized the physical chain from bridge to sound below 4 kHz via normal mode rms mobility and radiativity, total damping, radiation efficiency, and averaged directivity.
Abstract: Simultaneous modal and acoustical measurements on three violins characterized the physical chain from bridge to sound below 4 kHz via normal mode rms mobility and radiativity, total damping, radiation efficiency, and averaged directivity. The fraction of vibrational energy radiated as sound was estimated as 31%±10% for the 1st corpus bending modes. Radiation efficiencies ranged from ∼0.004 to ∼1, rising with frequency, with lower and upper 1st corpus bending mode values of 0.12±0.03 and 0.11±0.04 respectively. Averaged directivity rose slowly from ∼1 for the lowest modes to ∼2 at 4 kHz. The A1 cavity mode radiates effectively via induced corpus motion.
TL;DR: A new 3-channel system is proposed to improve system performance on sound separation and based on the robustness analysis of a crosstalk canceller, a modified-inverse filter technique is explored and demonstrated using two different examples of symmetric speaker positions.
Abstract: In a virtual sound imaging system, crosstalk cancellation filters are used to create an effective sweet spot for 3D sound reproduction via multiple loudspeakers. A new 3-channel system is proposed to improve system performance on sound separation. Based on the robustness analysis of a crosstalk canceller, a modified-inverse filter technique is explored and demonstrated using two different examples of symmetric speaker positions. The simulation results indicate that the present system is robust over a wider bandwidth compared to a conventional 2-channel system.
TL;DR: In this paper, a small thermoacoustic-Stirling engine demonstration device that can produce sound in excess of 100 dB at 560 Hz has been constructed, which consists of a quarter wavelength acoustic resonator with a smaller diameter coaxial regenerator positioned toward the resonator's closed end, thereby forming an acoustic feedback path around the regenerator.
Abstract: A small thermoacoustic-Stirling engine demonstration device that can produce sound in excess of 100 dB at 560 Hz has been constructed. The engine consists of a quarter wavelength acoustic resonator with a smaller diameter coaxial regenerator positioned toward the resonator’s closed end, thereby forming an acoustic feedback path around the regenerator. Acoustic oscillations begin spontaneously when the hot heat exchanger adjoining one end of the regenerator is heated to a sufficient temperature. A water stream in a second heat exchanger maintains the opposite end of the regenerator near ambient temperature. This device was inspired by the Backhaus-Swift engine and is a preliminary step in the investigation of regenerator operation at frequencies much higher than may be practical with mechanical or free-piston Stirling engines.
Abstract: There are only 200 to 300 Sumatran rhinos (Dicermoceros sumatrensis) left in the world. Sumatran rhinos are solitary, and their native habitat is dense tropical forest and mountain moss forest. Three Sumatran rhinos, housed at the Cincinnati Zoo, were recorded using Statham Radio microphones and Sony TCD-D8 DAT recorders. Sumatran rhinos produce sounds described as eeps, 70 Hz–4 kHz (57–92 dB); whales, 100 Hz–3.2 kHz (87 dB); and whistle-blows, 17 Hz–8 kHz (100 dB). The whistle-blows contain high level infrasound that would be advantageous for use in the rhino’s forest habitat. Some Sumatran rhino vocalizations resemble humpback whale signals.
TL;DR: The ability of a single acoustic element to produce a compact time domain signal from a multi-mode solid cylindrical waveguide using a time-reversal mirror (TRM) is considered in this paper.
Abstract: The ability of a single acoustic element to produce a compact time domain signal from a multi-mode solid cylindrical waveguide using a time-reversal mirror (TRM) is considered. Two, single element, longitudinal contact transducers were used to excite and receive multiple longitudinal modes in a fused quartz waveguide in a TRM experiment. The TRM is demonstrated to be effective with the limited information from a single longitudinal transducer. Experimental results are presented along with a simple interpretation that shows how a TRM with only a single element can be used as a practical sensor.
TL;DR: In this paper, the authors used parabolic equation and normal mode propagation models and the shallow water invariant, beta, to explain the focusing of refracted bottom reflected (RBR) rays/modes.
Abstract: Observations of multipath on the western shelf area of the Florida Straits have consistently revealed an intense arrival associated with refracted bottom reflected (RBR) rays/modes. The ‘late’ or ‘focused’ arrival is 15 to 20 dB higher than other arrivals. Parabolic Equation and Normal Mode propagation models and the shallow water invariant, beta, are used to explain the focusing. The sound speed profile that produces the focusing comes about from a combination of a strong downward refracting layer resulting from the geostrophic equilibrium of the Florida current on top of a well mixed turbulent bottom boundary layer. The resulting c(z) resembles cosh(g(1−z/D)), which produce perfect focusing at every range, that is, all RBR modes have the exact same group velocity.
TL;DR: A monitoring program documented densities of ringed seals, Phoca hispida, before and during development of the Northstar oil field in the central Alaskan Beaufort Sea as mentioned in this paper.
Abstract: A monitoring program documented densities of ringed seals, Phoca hispida, before and during development of the Northstar oil field in the central Alaskan Beaufort Sea. Aerial surveys of seals on landfast ice were conducted during the springs of 1997 to 1999 (pre-construction) and 2000–2001 (construction and drilling). Acoustic and vibration data were acquired during the ice-covered seasons of 2000 and 2001. Underwater sounds, in-air sounds, and iceborne vibrations from Northstar were above background levels to distances of 1–5, 0.5–4, and 1–4 km, respectively. However, seal densities close to Northstar in 2000 and 2001 were not reduced relative to those farther away or during the 1997 to 1999 period.
TL;DR: In this paper, a photoacoustic generation of bi-directional ultrasonic pulses by a thin optical absorber that is remote from the sample is described, and a single piezoelectric transducer ultimately detects the two pulses of ultrasound and the captured signals are used to determine both the optical absorption and ultrasonic attenuation properties of the sample.
Abstract: A novel method for the simultaneous acquisition of optical absorption and ultrasonic attenuation spectra is described. The technique is based on the photoacoustic generation of bi-directional ultrasonic pulses by a thin optical absorber that is remote from the sample. A single piezoelectric transducer ultimately detects the two pulses of ultrasound, and the captured signals are used to determine both the optical absorption and ultrasonic attenuation properties of the sample. Measurements on a polycarbonate resin sample using the simultaneous photoacoustic method and conventional techniques show good agreement, indicating the validity of the method.
TL;DR: Computer models illustrate that the nonuniform distributions of absorption in auditoria result in significant differences between the absorption coefficients derived by an in-situ measurement method and the true random-incidence absorption coefficients.
Abstract: Systematic errors in the high frequency predictions of geometrical acoustics software can result from the use of seat absorption coefficients derived by traditional measurement methods based on diffuse-field assumptions. This analysis treats in-situ measurement methods in which seat absorption coefficients are calculated by a diffuse-field model from reverberation time measurements made in auditoria. Computer models illustrate that the nonuniform distributions of absorption in auditoria result in significant differences between the absorption coefficients derived by an in-situ measurement method and the true random-incidence absorption coefficients. Proposals are made for methods to be used when measuring seat absorption coefficients for use in geometrical acoustics software.
TL;DR: In this paper, an experiment addressed perceptual assumptions that have formed the basis of models for auditory feature integration and evaluated the contribution of guessing, illusory conjunctions, and intertone distance.
Abstract: An experiment addressed perceptual assumptions that have formed the basis of models for auditory feature integration. Musicians searched stimuli containing two lateralized tones for a target timbre and its pitch. Errors representing potential illusory conjunctions exceeded feature misperception errors. Responses were submitted to multinomial models to evaluate the contribution of guessing, illusory conjunctions, and intertone distance. Illusory conjunction models provided the most accurate data fits. Illusory conjunction rates exceeded zero, and were not affected by distance. Implications for feature binding models are discussed.
TL;DR: In this paper, the authors show that when a structural network is driven at a point in one of its systems, other points in other systems may experience anomalously high response, termed hot spots.
Abstract: When a structural network is driven at a point in one of its systems, other points in other systems may experience anomalously high response. These are termed “hot spots.” The phenomena may be of importance in networks where one or more of the subsystems are fragile. Such networks may be driven in a robust system and break at a hot spot in a fragile system. The phenomena are demonstrated in the calculated spatial/temporal response of simple models of connected one-dimensional wave-bearing systems.
TL;DR: In this article, the propagation time of an acoustic pulse generated via an optoacoustic technique is analyzed and it is observed that the time duration is increased near the vaporization threshold of the liquid.
Abstract: The propagation time of an acoustic pulse generated via an optoacoustic technique is analyzed. The propagation time is delayed by approximately 225 ns once a stable bubble is produced due to vaporization of the liquid. Although there is little change in the general spatial and temporal profile of the acoustic wave, it is observed that the time duration is increased near the vaporization threshold of the liquid.
TL;DR: Three experiments examined whether the Clarion 1.2 S-Series cochlear implant could be safely and effectively used within a Carstens Medizinelektronik EMA (electromagnetic articulography) system and found no indication of reduced sentence repetition abilities when EMA fields were present.
Abstract: Three experiments examined whether the Clarion 1.2 S-Series cochlear implant could be safely and effectively used within a Carstens Medizinelektronik EMA (electromagnetic articulography) system. Experiment 1 indicated no measurable effects of EMA magnetic fields on implant function. Experiment 2 showed no influence of the implant on the accuracy of EMA measurements. Experiment 3 found no indication of reduced sentence repetition abilities when EMA fields were present. The results suggest experiments with the Clarion 1.2 cochlear implant and the Carstens AG100 articulograph are safe and feasible.