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Top 20 Most Read Articles
July 2011
The 20 articles with the most full-text downloads during the month, in descending order.
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Vibrato and tremor extent spectrum: Algorithm and applications J. Acoust. Soc. Am. Volume 130, Issue 1, pp. EL1-EL7 (2011); (7 pages)
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This work investigated the measurement of vibrato and tremor extent values. Related works have not explored the possibility of measuring extent in the spectra of fundamental frequency (f0) low-frequency undulations. It is shown here that by canceling average (DC) values and baseline drifts of f0 contours, as well as weighting the respective spectra by the time window DC value, extent measures can be promptly obtained in the frequency domain. The method is illustrated with measurements from synthetic and human data.
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Engaging concert hall acoustics is made up of temporal envelope preserving reflections J. Acoust. Soc. Am. Volume 129, Issue 6, pp. EL223-EL228 (2011); (6 pages) Online Publication Date: 11 May 2011
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Strong, exciting, and engaging sound is perceived in the best concert halls. Here, it is shown that wideband early reflections that preserve the temporal envelope of sound contribute to the clear and open acoustics with strong bass. Such reflections are fused with the direct sound due to the precedence effect. In contrast, reflections that distort the temporal envelope render the sound weak and muddy because they partially break down the precedence. The presented findings are based on the earlier psychoacoustics research, and confirmed by a perceptual evaluation with six simulated concert halls that have same monaural room acoustical parameter values according to ISO3382-1.
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J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 3754-3754 (2008); (1 page)
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A new method to compute underwater sound fields in irregular planar waveguides is proposed. It realizes the full two‐way propagation approach and exploits an idea of a problem solution dependence on a certain variable parameter that is the position of a boundary of the irregular region. With respect to this parameter for waveguide modes, an initial value problem can be formulated in the horizontal plane that is completely equivalent to the boundary value problem for the original wave equation (Helmholtz equation). This fact allows simulation of sound fields in waveguides based on ordinary differential equations with traditional approximations and for arbitrary source distance from the irregular region and the degree of irregularities. Examples of a simulation for a 2‐D irregular waveguide model with an upslope rigid or absorbing penetrable bottom are presented for low frequencies and shallow sea conditions. They illustrate the strong difference between our solution and approximate solutions that arise due to both mode coupling and considerable backscattering within the considered irregular waveguide models |
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Rupture of anterior cruciate ligament monitored by acoustic emission J. Acoust. Soc. Am. Volume 129, Issue 6, pp. EL217-EL222 (2011); (6 pages)
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The scope of this study is to relate the acoustic emission (AE) during rupture of human soft tissue (anterior cruciate ligament, ACL) to the mechanisms leading to its failure. The cumulative AE activity highlights the onset of serious damage, while other parameters, show repeatable tendencies, being well correlated with the tissue’s mechanical behavior. The frequency content of AE signals increases throughout the experiment, while other indices characterize between different modes of failure. Results of this preliminary study show that AE can shed light into the failure process of this tissue, and provide useful data on the ACL reconstruction.
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Evolution of statistical properties for a nonlinearly propagating sinusoid J. Acoust. Soc. Am. Volume 130, Issue 1, pp. EL8-EL13 (2011); (6 pages)
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The nonlinear propagation of a pure sinusoid is considered using time domain statistics. The probability density function, standard deviation, skewness, kurtosis, and crest factor are computed for both the amplitude and amplitude time derivatives as a function of distance. The amplitude statistics vary only in the postshock realm, while the amplitude derivative statistics vary rapidly in the preshock realm. The statistical analysis also suggests that the sawtooth onset distance can be considered to be earlier than previously realized.
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Low-frequency noise from large wind turbines J. Acoust. Soc. Am. Volume 129, Issue 6, pp. 3727-3744 (2011); (18 pages)
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As wind turbines get larger, worries have emerged that the turbine noise would move down in frequency and that the low-frequency noise would cause annoyance for the neighbors. The noise emission from 48 wind turbines with nominal electric power up to 3.6 MW is analyzed and discussed. The relative amount of low-frequency noise is higher for large turbines (2.3–3.6 MW) than for small turbines (≤ 2 MW), and the difference is statistically significant. The difference can also be expressed as a downward shift of the spectrum of approximately one-third of an octave. A further shift of similar size is suggested for future turbines in the 10-MW range. Due to the air absorption, the higher low-frequency content becomes even more pronounced, when sound pressure levels in relevant neighbor distances are considered. Even when A-weighted levels are considered, a substantial part of the noise is at low frequencies, and for several of the investigated large turbines, the one-third-octave band with the highest level is at or below 250 Hz. It is thus beyond any doubt that the low-frequency part of the spectrum plays an important role in the noise at the neighbors.
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J. Acoust. Soc. Am. Volume 130, Issue 1, pp. 334-349 (2011); (16 pages)
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Temporal fine structure (TFS) sensitivity, frequency selectivity, and speech reception in noise were measured for young normal-hearing (NHY), old normal-hearing (NHO), and hearing-impaired (HI) subjects. Two measures of TFS sensitivity were used: the “TFS-LF test” (interaural phase difference discrimination) and the “TFS2 test” (discrimination of harmonic and frequency-shifted tones). These measures were not significantly correlated with frequency selectivity (after partialing out the effect of audiometric threshold), suggesting that insensitivity to TFS cannot be wholly explained by a broadening of auditory filters. The results of the two tests of TFS sensitivity were significantly but modestly correlated, suggesting that performance of the tests may be partly influenced by different factors. The NHO group performed significantly more poorly than the NHY group for both measures of TFS sensitivity, but not frequency selectivity, suggesting that TFS sensitivity declines with age in the absence of elevated audiometric thresholds or broadened auditory filters. When the effect of mean audiometric threshold was partialed out, speech reception thresholds in modulated noise were correlated with TFS2 scores, but not measures of frequency selectivity or TFS-LF test scores, suggesting that a reduction in sensitivity to TFS can partly account for the speech perception difficulties experienced by hearing-impaired subjects.
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English-learning infants’ perception of word stress patterns J. Acoust. Soc. Am. Volume 130, Issue 1, pp. EL50-EL55 (2011); (6 pages) Online Publication Date: 01 Jul 2011
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Adult speakers of different free stress languages (e.g., English, Spanish) differ both in their sensitivity to lexical stress and in their processing of suprasegmental and vowel quality cues to stress. In a head-turn preference experiment with a familiarization phase, both 8-month-old and 12-month-old English-learning infants discriminated between initial stress and final stress among lists of Spanish-spoken disyllabic nonwords that were segmentally varied (e.g. [ˈnila, ˈtuli] vs [luˈta, puˈki]). This is evidence that English-learning infants are sensitive to lexical stress patterns, instantiated primarily by suprasegmental cues, during the second half of the first year of life.
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Temporal integration of loudness measured using categorical loudness scaling and matching procedures J. Acoust. Soc. Am. Volume 130, Issue 1, pp. EL32-EL37 (2011); (6 pages) Online Publication Date: 23 Jun 2011
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Temporal integration of loudness of 1 kHz tones with 5 and 200 ms durations was assessed in four subjects using two loudness measurement procedures: categorical loudness scaling (CLS) and loudness matching. CLS provides a reliable and efficient procedure for collecting data on the temporal integration of loudness and previously reported nonmonotonic behavior observed at mid-sound pressure level levels is replicated with this procedure. Stimuli that are assigned to the same category are effectively matched in loudness, allowing the measurement of temporal integration with CLS without curve-fitting, interpolation, or assumptions concerning the form of the loudness growth function.
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Stoneley waves in three-layered cylindrical solid media J. Acoust. Soc. Am. Volume 130, Issue 1, pp. EL44-EL49 (2011); (6 pages) Online Publication Date: 28 Jun 2011
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This paper considers the propagation of Stoneley modes along the interfaces of three-layered concentric cylindrical solid media in order to assist in the design of ultrasonic transmission rods. The phase velocity dispersion curves and amplitude distributions are numerically analyzed. The modes are analogous to non-dispersive Stoneley waves and are confined to the vicinities of the two interfaces at high frequency. A key finding is that the peak amplitude location for each mode transfers between the two interfaces as a function of frequency. A simplified model is introduced, giving the peak amplitude locations of each mode in different frequency ranges efficiently.
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Effect of source spectrum on sound localization in an everyday reverberant room J. Acoust. Soc. Am. Volume 130, Issue 1, pp. 324-333 (2011); (10 pages)
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Two experiments explored how frequency content impacts sound localization for sounds containing reverberant energy. Virtual sound sources from thirteen lateral angles and four distances were simulated in the frontal horizontal plane using binaural room impulse responses measured in an everyday office. Experiment 1 compared localization judgments for one-octave-wide noise centered at either 750 Hz (low) or 6000 Hz (high). For both band-limited noises, perceived lateral angle varied monotonically with source angle. For frontal sources, perceived locations were similar for low- and high-frequency noise; however, for lateral sources, localization was less accurate for low-frequency noise than for high-frequency noise. With increasing source distance, judgments of both noises became more biased toward the median plane, an effect that was greater for low-frequency noise than for high-frequency noise. In Experiment 2, simultaneous presentation of low- and high-frequency noises yielded performance that was less accurate than that for high-frequency noise, but equal to or better than for low-frequency noise. Results suggest that listeners perceptually weight low-frequency information heavily, even in reverberant conditions where high-frequency stimuli are localized more accurately. These findings show that listeners do not always optimally adjust how localization cues are integrated over frequency in reverberant settings.
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Influence of impression of vehicle styling on loudness of acceleration sounds in cabin J. Acoust. Soc. Am. Volume 130, Issue 1, pp. EL19-EL24 (2011); (6 pages)
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The influence of participants’ impressions of vehicle styling on the loudness of acceleration sounds was investigated. A series of images of luxury or sporty vehicles was presented to the participants as acceleration sounds were being replayed. The results indicated that participants who were frequent drivers felt that the sound associated with luxury vehicles was louder than that associated with sporty vehicles. However, participants who rarely drove perceived almost no difference between the loudness of the two vehicles types. Thus, the loudness was shown to depend on both the participants’ impression of the vehicle and their driving frequency.
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A statistical model of horizontal auditory localization performance data J. Acoust. Soc. Am. Volume 129, Issue 6, pp. EL229-EL235 (2011); (7 pages)
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Horizontal localization experiments are used to evaluate the listener’s ability to locate the position of a sound source, and determine how signal characteristics affect this ability. These experiments generate circular, bimodal, and repeated data that are challenging to statistically analyze. A two-part mixture of wrapped Cauchys is proposed for these data, with the effects of signal type and position on localization bias, precision, and front-back confusion modeled using regression. The model is illustrated using mid- (1.0–2.0 kHz) and high- (3.0–6.0 kHz) frequency narrow band noises localization collected among ten normal hearing listeners.
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On the mechanisms involved in the recovery of envelope information from temporal fine structure J. Acoust. Soc. Am. Volume 130, Issue 1, pp. 273-282 (2011); (10 pages)
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Three experiments were designed to provide psychophysical evidence for the existence of envelope information in the temporal fine structure (TFS) of stimuli that were originally amplitude modulated (AM). The original stimuli typically consisted of the sum of a sinusoidally AM tone and two unmodulated tones so that the envelope and TFS could be determined a priori. Experiment 1 showed that normal-hearing listeners not only perceive AM when presented with the Hilbert fine structure alone but AM detection thresholds are lower than those observed when presenting the original stimuli. Based on our analysis, envelope recovery resulted from the failure of the decomposition process to remove the spectral components related to the original envelope from the TFS and the introduction of spectral components related to the original envelope, suggesting that frequency- to amplitude-modulation conversion is not necessary to recover envelope information from TFS. Experiment 2 suggested that these spectral components interact in such a way that envelope fluctuations are minimized in the broadband TFS. Experiment 3 demonstrated that the modulation depth at the original carrier frequency is only slightly reduced compared to the depth of the original modulator. It also indicated that envelope recovery is not specific to the Hilbert decomposition.
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Psychometric functions for pure-tone frequency discrimination J. Acoust. Soc. Am. Volume 130, Issue 1, pp. 263-272 (2011); (10 pages)
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The form of the psychometric function (PF) for auditory frequency discrimination is of theoretical interest and practical importance. In this study, PFs for pure-tone frequency discrimination were measured for several standard frequencies (200–8000 Hz) and levels [35–85 dB sound pressure level (SPL)] in normal-hearing listeners. The proportion-correct data were fitted using a cumulative-Gaussian function of the sensitivity index, d′, computed as a power transformation of the frequency difference, Δf. The exponent of the power function corresponded to the slope of the PF on log(d′)-log(Δf) coordinates. The influence of attentional lapses on PF-slope estimates was investigated. When attentional lapses were not taken into account, the estimated PF slopes on log(d′)-log(Δf) coordinates were found to be significantly lower than 1, suggesting a nonlinear relationship between d′ and Δf. However, when lapse rate was included as a free parameter in the fits, PF slopes were found not to differ significantly from 1, consistent with a linear relationship between d′ and Δf. This was the case across the wide ranges of frequencies and levels tested in this study. Therefore, spectral and temporal models of frequency discrimination must account for a linear relationship between d′ and Δf across a wide range of frequencies and levels.
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J. Acoust. Soc. Am. Volume 130, Issue 1, pp. 20-32 (2011); (13 pages)
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Numerical simulation of nonlinear acoustics and shock waves in a weakly heterogeneous and lossless medium is considered. The wave equation is formulated so as to separate homogeneous diffraction, heterogeneous effects, and nonlinearities. A numerical method called heterogeneous one-way approximation for resolution of diffraction (HOWARD) is developed, that solves the homogeneous part of the equation in the spectral domain (both in time and space) through a one-way approximation neglecting backscattering. A second-order parabolic approximation is performed but only on the small, heterogeneous part. So the resulting equation is more precise than the usual standard or wide-angle parabolic approximation. It has the same dispersion equation as the exact wave equation for all forward propagating waves, including evanescent waves. Finally, nonlinear terms are treated through an analytical, shock-fitting method. Several validation tests are performed through comparisons with analytical solutions in the linear case and outputs of the standard or wide-angle parabolic approximation in the nonlinear case. Numerical convergence tests and physical analysis are finally performed in the fully heterogeneous and nonlinear case of shock wave focusing through an acoustical lens.
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Low frequency deep ocean ambient noise trend in the Northeast Pacific Ocean J. Acoust. Soc. Am. Volume 129, Issue 5, pp. EL161-EL165 (2011); (5 pages) Online Publication Date: 11 Apr 2011
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Concern about effects of anthropogenic noise on marine life has stimulated new studies to establish present-day ocean noise levels and compare them to noise levels from previous times. This paper reports on the trend in low-frequency (10–400 Hz) ambient noise levels and presents measurements made using a calibrated multi-element volume array at deep ocean sites in the Northeast Pacific from 1978 to 1986. The experiments provided spectral noise levels as well as horizontal and vertical noise directionality. The data presented here provide evidence that the trend derived from 1960s data extended to around 1980, but has since continued at a lower rate.
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J. Acoust. Soc. Am. Volume 130, Issue 1, pp. EL25-EL31 (2011); (7 pages) Online Publication Date: 23 Jun 2011
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The pressure-particle velocity (PU) impedance measurement technique is an experimental method used to measure the surface impedance and the absorption coefficient of acoustic samples in situ or under free-field conditions. In this paper, the measurement uncertainty of the the absorption coefficient determined using the PU technique is explored applying the Monte Carlo method. It is shown that because of the uncertainty, it is particularly difficult to measure samples with low absorption and that difficulties associated with the localization of the acoustic centers of the sound source and the PU sensor affect the quality of the measurement roughly to the same extent as the errors in the transfer function between pressure and particle velocity do.
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J. Acoust. Soc. Am. Volume 130, Issue 1, pp. 208-218 (2011); (11 pages)
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The acoustic properties of a compound micro-perforated panel (MPP) absorber array are investigated. The absorber array consists of three parallel-arranged MPP absorbers with different cavity depths. A finite element procedure is used to simulate its acoustic behaviors under normal incidence. Experimental studies are carried out to verify the numerical simulations. Due to different reactance matching conditions in the absorber array, strong local resonance occurs and the corresponding local resonance absorption dominates. Compared with single MPP absorber, the absorber array requires lower acoustic resistance for good absorption performance, and the resonance frequencies shift due to inter-resonator interactions. The different acoustic resistance requirement is explained by considering the reduced effective perforation rate of the MPP in the absorber array. The performance of the absorber array varies with the sizes and spatial arrangement of the component absorbers. When the distance between component absorbers is larger than a quarter-wavelength, the above-mentioned parallel absorption mechanism diminishes. In the experimental study, the normal incidence absorption coefficients of a prototype MPP absorber array are tested. The measured results compare well with the numerical predictions. The experimental study also shows that although other absorption mechanisms may exist, dissipation by the MPP is dominant in the MPP absorber array.
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A particle filtering approach for spatial arrival time tracking in ocean acoustics J. Acoust. Soc. Am. Volume 129, Issue 6, pp. EL236-EL241 (2011); (6 pages)
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The focus of this work is on arrival time and amplitude estimation from acoustic signals recorded at spatially separated hydrophones in the ocean. A particle filtering approach is developed that treats arrival times as “targets” and tracks their “location” across receivers, also modeling arrival time gradient. The method is evaluated via Monte Carlo simulations and is compared to a maximum likelihood estimator, which does not relate arrivals at neighboring receivers. The comparison demonstrates a significant advantage in using the particle filter. It is also shown that posterior probability density functions of times and amplitudes become readily available with particle filtering.
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