- jasa express letters
- acoustical oceanography
- animal bioacoustics
- architectural acoustics
- biomedical acoustics
- engineering acoustics
- physical acoustics
- psychological and physiological acoustics
- signal processing in acoustics
- speech communication
- structural acoustics and vibration
- underwater acoustics
- letters to the editor
- acoustical news
- acoustical standards news
- reviews of acoustical patents
Index of content:
Volume 138, Issue 3, September 2015
- JASA EXPRESS LETTERS
138(2015); http://dx.doi.org/10.1121/1.4929623View Description Hide Description
The characteristics of using a laser-induced spark as a monopole source in scale model measurements were assessed by comparison with an electric spark and a miniature spherical loudspeaker. Room impulse responses of first order directivity sources were synthesized off-line using six spatially distributed sparks. The source steering direction was scanned across the horizontal and vertical plane to assess the origin of early reflections. The results confirm that the characteristics of the laser-induced spark outperform those of typical sources. Its monopole characteristics enable the authors to synthesize room responses of directional sources, e.g., to obtain directional information about reflections inside scale models.
138(2015); http://dx.doi.org/10.1121/1.4929627View Description Hide Description
This study examined the effects of sentence predictability and masker modulation type on the fluctuating masker benefit (FMB), the improvement in speech reception thresholds resulting from fluctuations imposed on a steady-state masker. Square-wave modulations resulted in a larger FMB than sinusoidal ones. FMBs were also larger for high compared to low-predictability sentences, indicating that high sentence predictability increases the benefits from glimpses of the target speech in the dips of the fluctuating masker. In addition, sentence predictability appears to have a greater effect on sentence intelligibility when the masker is fluctuating than when it is steady-state.
138(2015); http://dx.doi.org/10.1121/1.4929614View Description Hide Description
This study compares two response-time measures of listening effort that can be combined with a clinical speech test for a more comprehensive evaluation of total listening experience; verbal response times to auditory stimuli (RTaud) and response times to a visual task (RTsvis) in a dual-task paradigm. The listening task was presented in five masker conditions; no noise, and two types of noise at two fixed intelligibility levels. Both the RTsaud and RTsvis showed effects of noise. However, only RTsaud showed an effect of intelligibility. Because of its simplicity in implementation, RTsaud may be a useful effort measure for clinical applications.
138(2015); http://dx.doi.org/10.1121/1.4929620View Description Hide Description
Absolute pressure measurements of acoustic emissions by single-element, focused passive cavitation detectors would be facilitated by improved wideband receive calibration techniques. Here, calibration methods were developed to characterize the absolute, frequency-dependent receive sensitivity of a spherically focused, single-element transducer using pulse-echo and pitch-catch techniques. Validation of these calibration methods on a focused receiver were made by generating a pulse from a small diameter source at the focus of the transducer and comparing the absolute pressure measured by a calibrated hydrophone to that of the focused transducer using the receive sensitivities determined here.
138(2015); http://dx.doi.org/10.1121/1.4929616View Description Hide Description
Analysis of English rhythm in speech produced by children and adults revealed that speech rhythm becomes increasingly more stress-timed as language acquisition progresses. Children reach the adult-like target by 11 to 12 years. The employed speech elicitation paradigm ensured that the sentences produced by adults and children at different ages were comparable in terms of lexical content, segmental composition, and phonotactic complexity. Detected differences between child and adult rhythm and between rhythm in child speech at various ages cannot be attributed to acquisition of phonotactic language features or vocabulary, and indicate the development of language-specific phonetic timing in the course of acquisition.
138(2015); http://dx.doi.org/10.1121/1.4929624View Description Hide Description
Two experiments tested the influence of hearing impairment (HI) on representing across-frequency temporal coherence. In one experiment, HI listeners demonstrated similar abilities to normal-hearing listeners in detecting across-frequency differences in modulation phase. In another, spectral-shape discrimination was detrimentally affected by modulation phase disparities imposed on spectral components. Spectral-shape discrimination by HI listeners was less influenced by the disparities, suggesting that hearing loss alters the representation of envelope phase. Results suggest that multiple approaches may be necessary to determine alterations associated with hearing loss—detection tasks may not be sufficient to elucidate distortions to temporal envelope associated with hearing loss.
138(2015); http://dx.doi.org/10.1121/1.4929621View Description Hide Description
In this study the movement patterns of ten expert musicians are quantitatively related to expressive timing patterns and the music structure during performances. The hypothesis is that ancillary gestures recurrently employed are closely related to expressive intentions, and that the expressive content imposed in key musical passages is thus reflected in the patterns of gestural recurrence. A movement and an audio analysis of 30 clarinet performances of a Brahms' excerpt are compared. Results show direct correlations between the recurrence pattern of clarinetists' ancillary movements and expressive bar duration manipulations employed by them, associated with melodic phrasing and harmonic transitions.
138(2015); http://dx.doi.org/10.1121/1.4929625View Description Hide Description
This paper investigates the feasibility of broadband sound blocking with rotationally symmetric extensible inclusions introduced in phononic crystals. By varying the size of four equally shaped inclusions gradually, the phononic crystal experiences remarkable changes in its band-stop properties, such as shifting/widening of multiple Bragg bandgaps and evolution to resonance gaps. Necessary extensions of the inclusions to block sound effectively can be determined for given incident frequencies by evaluating power transmission characteristics. By arraying finite dissimilar unit cells, the resulting phononic crystal exhibits broadband sound blocking from combinational effects of multiple Bragg scattering and local resonances even with small-numbered cells.
138(2015); http://dx.doi.org/10.1121/1.4929622View Description Hide Description
Non-native speech differs from native speech in multiple ways. Previous research has described segmental and suprasegmental differences between native and non-native speech in terms of group averages. For example, average speaking rate for non-natives is slower than for natives. However, it is unknown whether non-native speech is also more variable than native speech. This study introduces a method of comparing rate change across utterances, demonstrating that non-native speaking rate is more variable than native speech. These results suggest that future work examining non-native speech perception and production should investigate both mean differences and variability in the signal.
138(2015); http://dx.doi.org/10.1121/1.4929626View Description Hide Description
The problem of nonlinear acoustic to articulatory inversion mapping is investigated in the feature space using two models, the deep belief network (DBN) which is the state-of-the-art, and the general regression neural network (GRNN). The task is to estimate a set of articulatory features for improved speech recognition. Experiments with MOCHA-TIMIT and MNGU0 databases reveal that, for speech inversion, GRNN yields a lower root-mean-square error and a higher correlation than DBN. It is also shown that conjunction of acoustic and GRNN-estimated articulatory features yields state-of-the-art accuracy in broad class phonetic classification and phoneme recognition using less computational power.
138(2015); http://dx.doi.org/10.1121/1.4929629View Description Hide Description
A duct silencer with tunable acoustic characteristics is presented in this paper. Dielectric elastomer, a smart material with lightweight, high elastic energy density and large deformation under high direct current/alternating current voltages, was used to fabricate this duct silencer. The acoustic performances and tunable mechanisms of this duct silencer were experimentally investigated. It was found that all the resonance peaks of this duct silencer could be adjusted using external control signals without any additional mechanical part. The physics of the tunable mechanism is further discussed based on the electro-mechanical interactions using finite element analysis. The present promising results also provide insight into the appropriateness of the duct silencer for possible use as next generation acoustic treatment device to replace the traditional acoustic treatment.
138(2015); http://dx.doi.org/10.1121/1.4929628View Description Hide Description
This paper presents a relationship between the celerity and trace velocity of infrasound signals propagating in a stratified, windy atmosphere. Despite their importance, known celerity values have only been determined empirically. An infrasonic phase (I-phase) diagram is developed which is useful in identifying different I-phases. Such an I-phase diagram allows for the prediction of the range of values of the celerity and trace velocity for each I-phase. The phase diagram can easily be extended to underwater acoustic and acoustic-gravity waves. An I-phase diagram is compared with data obtained from a ground-truth event where qualitative agreement is obtained.
138(2015); http://dx.doi.org/10.1121/1.4929733View Description Hide Description
Reverberant sound fields are often modeled as isotropic. However, it has been observed that spatial properties change during the decay of the sound field energy, due to non-isotropic attenuation in non-ideal rooms. In this letter, a model for the spatial coherence between two sensors in a decaying reverberant sound field is developed for rectangular rooms. The modeled coherence function depends on room dimensions, surface reflectivity, and orientation of the sensor pair, but is independent of the position of source and sensors in the room. The model includes the spherically isotropic (diffuse) and cylindrically isotropic sound field models as special cases.
138(2015); http://dx.doi.org/10.1121/1.4929730View Description Hide Description
Acoustically thin metamaterial underwater noise isolation panels have been developed that provide as much as 16 dB of noise isolation for a panel with a thickness just 160th of the wavelength in the host medium (fresh water) at 2.5 kHz. The panels are composed of thin layers of neoprene rubber and polyoxymethylene containing air-filled voids. The level of isolation provided by the panels is shown to correlate positively with the volume fraction of air voids within the panel.
138(2015); http://dx.doi.org/10.1121/1.4929736View Description Hide Description
Knowledge of distinct effects of moisture content and air volume on acoustic properties of soil is sought to predict the influence of human activities such as cultivation on acoustic propagation outdoors. This work used an impedance tube with the two-thickness method to investigate such effects. For a constant moisture weight percentage, the magnitude of the characteristic impedance became smaller and the absorption coefficient became higher with increase of the air space ratio. For a constant air space ratio, the absorption coefficient became larger and the magnitude of the propagation constant became smaller with increasing moisture weight percentage.
138(2015); http://dx.doi.org/10.1121/1.4929619View Description Hide Description
The mean sound exposure level from a source is routinely estimated by the mean of the observed sound exposures from repeated measurements. A formula for the standard uncertainty based on the Guide to the expression of Uncertainty in Measurement (GUM) is derived. An alternative formula is derived for the case where the GUM method fails. The formulas are applied on several examples, and compared with a Monte Carlo calculation of the standard uncertainty. The recommended formula can be seen simply as a convenient translation of the uncertainty on an energy scale into the decibel level scale, but with a theoretical foundation.
138(2015); http://dx.doi.org/10.1121/1.4929735View Description Hide Description
An equivalent analog circuit is designed to mimic the coupled ears of the fly Ormia ochracea for sound source localization. This coupled circuit receives two signals with tiny phase difference from a space closed two-microphone array, and produces two signals with obvious intensity difference. The response sensitivity can be adjusted through the coupled circuit parameters. The directional characteristics of the coupled circuit have been demonstrated in the experiment. The miniature microphone array can localize the sound source with low computational burden by using the intensity difference. This system has significant advantages in various applications where the array size is limited.
138(2015); http://dx.doi.org/10.1121/1.4929734View Description Hide Description
Using echolocation influenced by Doppler shift, bats can capture flying insects in real three-dimensional space. On the basis of this principle, a model that estimates object locations using frequency modulated (FM) sound was proposed. However, no investigation was conducted to verify whether the model can localize flying insects from their echoes. This study applied the model to estimate the range and direction of flying insects by extracting temporal changes from the time-frequency pattern and interaural range difference, respectively. The results obtained confirm that a living insect's position can be estimated using this model with echoes measured while emitting intermittent FM sounds.
138(2015); http://dx.doi.org/10.1121/1.4929630View Description Hide Description
This letter proposes an efficient parameterization of the three-dimensional room transfer function (RTF) which is robust for the position variations of source and receiver in respective horizontal planes. Based on azimuth harmonic analysis, the proposed method exploits the underlying properties of the associated Legendre functions to remove a portion of the spherical harmonic coefficients of RTF which have no contribution in the horizontal plane. This reduction leads to a flexible measuring-point structure consisting of practical concentric circular arrays to extract horizontal plane RTF coefficients. The accuracy of the above parameterization is verified through numerical simulations.
Empirical estimation of peak pressure level from sound exposure level. Part II: Offshore impact pile driving noise138(2015); http://dx.doi.org/10.1121/1.4929742View Description Hide Description
Numerical models of underwater sound propagation predict the energy of impulsive signals and its decay with range with a better accuracy than the peak pressure. A semi-empirical formula is suggested to predict the peak pressure of man-made impulsive signals based on numerical predictions of their energy. The approach discussed by Galindo-Romero, Lippert, and Gavrilov [J. Acoust. Soc. Am. 138, in press (2015)] for airgun signals is modified to predict the peak pressure from offshore pile driving, which accounts for impact and pile parameters. It is shown that using the modified empirical formula provides more accurate predictions of the peak pressure than direct numerical simulations of the signal waveform.