Volume 123, Issue 4, April 2008
- jasa express letters
- acoustical news—usa
- acoustical news—international
- book reviews
- reviews of acoustical patents
- letters to the editor
- general linear acoustics 
- nonlinear acoustics 
- underwater sound 
- ultrasonics, quantum acoustics, and physical effects of sound 
- transduction 
- structural acoustics and vibration 
- architectural acoustics 
- acoustical measurements and instrumentation 
- acoustic signal processing 
- physiological acoustics 
- psychological acoustics 
- speech production 
- speech perception 
- psychological acoustics 
- music and musical instruments 
- bioacoustics 
Index of content:
- JASA EXPRESS LETTERS
123(2008); http://dx.doi.org/10.1121/1.2884083View Description Hide Description
While acoustic tissue mimicking materials have been explored for a variety of soft and hard biological tissues, no dental hard tissue mimicking materials have been characterized. Tooth phantoms are necessary to better understand acoustic phenomenology within the tooth environment and to accelerate the advancement of dental ultrasound imaging systems. In this study, soda lime glass and dental composite were explored as surrogates for human enamel and dentin, respectively, in terms of compressional velocity,attenuation, and acoustic impedance. The results suggest that a tooth phantom consisting of glass and composite can effectively mimic the acoustic behavior of a natural human tooth.
123(2008); http://dx.doi.org/10.1121/1.2884084View Description Hide Description
It has traditionally been thought that performance in two-interval frequency discrimination tasks decreases as the range over which the standard tone varies is increased. Recent empirical evidence and a reexamination of previous results suggest that this may not be the case. The present experiment found that performance was significantly better when the standard roved over a wide range than a narrow range . This pattern cannot readily be accommodated by traditional models of frequency discrimination based on memory or attention, but may be explicable in terms of neural plasticity and the formation of perceptual anchors.
123(2008); http://dx.doi.org/10.1121/1.2884085View Description Hide Description
The goal of this study was to measure the ability of normal-hearing listeners to discriminate formant frequency for vowels in isolation and sentences at three signal levels. Results showed significant elevation in formant thresholds as formant frequency and linguistic context increased. The signal level indicated a rollover effect, especially for F2, in which formant thresholds at SPL were lower than thresholds at 70 or SPL in both isolated vowels and sentences. This rollover level effect could be due to reduced frequency selectivity and forward/backward masking in sentence at high signal levels for normal-hearing listeners.
123(2008); http://dx.doi.org/10.1121/1.2884086View Description Hide Description
Most binary-mask studies assume a fine time–frequency representation of the signal that may not be available in some applications (e.g., cochlear implants). This study assesses the effect of spectral resolution on intelligibility of ideal-binary masked speech. In Experiment 1, speech corrupted in noise at signal-to-noise ratio (SNR) was filtered into 6–32 channels and synthesized using the ideal binary mask. Results with normal-hearing listeners indicated substantial improvements in intelligibility with 24–32 channels, particularly in SNR. Results from Experiment 2 indicated that having access to the ideal binary mask in the F1/F2 region is sufficient for good performance.
Interpretations on principal components analysis of head-related impulse responses in the median planea)123(2008); http://dx.doi.org/10.1121/1.2884094View Description Hide Description
A principal components analysis of the median-plane head-related impulse responses (HRIRs) in the CIPIC HRTF database reveals that the individual HRIRs can be reconstructed by a linear combination of 12 principal components (PCs) within 5% of error in the least-squares sense. The PCs include the intersubject and interelevation variations in the median-plane HRIRs. Each PC provides sound cues for the front–back discrimination and/or the vertical perception. There exist common systematic elevation dependencies in the weights of lower-numbered PCs which contribute to the pinna/head diffractions, whereas the elevation dependencies in the weights of higher-numbered PCs are different from subject to subject.
123(2008); http://dx.doi.org/10.1121/1.2884349View Description Hide Description
A single pool of untrained subjects was tested for interactions across two bimodal perception conditions: audio-tactile, in which subjects heard and felt speech, and visual-tactile, in which subjects saw and felt speech. Identifications of English obstruent consonants were compared in bimodal and no-tactile baseline conditions. Results indicate that tactile information enhances speech perception by about 10 percent, regardless of which other mode (auditory or visual) is active. However, within-subject analysis indicates that individual subjects who benefit more from tactile information in one cross-modal condition tend to benefit less from tactile information in the other.
123(2008); http://dx.doi.org/10.1121/1.2896106View Description Hide Description
Listeners without absolute (or “perfect”) pitch have difficulty identifying or producing isolated musical pitches from memory. Instead, they process the relative pattern of pitches, which remains invariant across pitch transposition. Musically untrained non-absolute pitch possessors demonstrated absolute pitch memory for the telephone dial tone, a stimulus that is always heard at the same absolute frequency. Listeners accurately classified pitch-shifted versions of the dial tone as “normal,” “higher than normal” or “lower than normal.” However, the role of relative pitch processing was also evident, in that listeners’ pitch judgments were also sensitive to the frequency range of stimuli.
Simultaneous estimation of attenuation and structure parameters of aggregated red blood cells from backscatter measurements123(2008); http://dx.doi.org/10.1121/1.2896115View Description Hide Description
The analysis of the ultrasonic frequency-dependent backscatter coefficient of aggregating red blood cells reveals information about blood structural properties. The difficulty in applying this technique in vivo is due to the frequency-dependent attenuation caused by intervening tissue layers that distorts the spectral content of backscattering properties from blood microstructures. An optimization method is proposed to simultaneously estimate tissue attenuation and blood structure factor. With in vitro experiments, the method gave satisfactory estimates with relative errors below 22% for attenuations between 0.101 and , signal-to-noise and ( being the wave number and the aggregate radius).
123(2008); http://dx.doi.org/10.1121/1.2800893View Description Hide Description
Binaural disparities are the primary acoustic cues employed in sound localization tasks. However, the degree of binaural correlation in a sound serves as a complementary cue for detecting competing sound sources [J. F. Culling, H. S. Colburn, and M. Spurchise, “Interaural correlation sensitivity,” J. Acoust. Soc. Am.110(2), 1020–1029 (2001) and L. R. Bernstein and C. Trahiotis, “On the use of the normalized correlation as an index of interaural envelope correlation,” J. Acoust. Soc. Am.100, 1754–1763 (1996)]. Here a random chord stereogram (RCS) sound is developed that produces a salient pop-out illusion of a slowly varying ripple sound [T. Chi et al., “Spectro-temporal modulation transfer functions and speech intelligibility,” J. Acoust. Soc. Am.106(5), 2719–2732 (1999)], even though the left and right ear sounds alone consist of noise-like random modulations. The quality and resolution of this percept is systematically controlled by adjusting the spectrotemporal correlation pattern between the left and right sounds. The prominence and limited time-frequency resolution for resolving the RCS suggests that envelope correlations are a dominant binaural cue for grouping acoustic objects.
123(2008); http://dx.doi.org/10.1121/1.2884081View Description Hide Description
The low-frequency sound speed in a fluid-like kaolinite sediment containing air bubbles was measured using an acoustic resonator technique and found to be with negligible dispersion between 100 and . The sediment’s void fraction and bubble size distribution was determined from volumetric images obtained from x-ray computed tomography scans. A simplified version of Wood’s effective medium model, which is dependent only upon the ambient pressure, the void fraction, the sediment’s bulk mass density, and the assumption that all the bubbles are smaller than resonance size at the highest frequency of interest, described the measuredsound speed.
123(2008); http://dx.doi.org/10.1121/1.2884082View Description Hide Description
It has been observed that children’s early vocabulary is dominated by nouns, with verbs being much delayed. The current study investigated if this delay is related to infants’ failure to segment verb forms. Using a preferential looking procedure, French-learning preverbal infants were tested on novel verbs segmentation. Infants at the onset of vocabulary learning (11-month-olds) succeeded in segmenting the targets: they listened longer to test sentences containing previously familiarized verbs versus those containing nonfamiliarized verbs, suggesting that the delay in verb learning is not due to segmentation difficulty. Semantic and syntactic complexities of verbs could be among the underlying factors.
- BOOK REVIEWS
123(2008); http://dx.doi.org/10.1121/1.2883743View Description Hide Description
- REVIEWS OF ACOUSTICAL PATENTS
123(2008); http://dx.doi.org/10.1121/1.2841175View Description Hide Description
The purpose of these acoustical patent reviews is to provide enough information for a Journal reader to decide whether to seek more information from the patent itself. Any opinions expressed here are those of the reviewers as individuals and are not legal opinions. Printed copies of United States Patents may be ordered at $3.00 each from the Commissioner of Patents and Trademarks, Washington, DC 20231. Patents are available via the Internet at http://www.uspto.gov.
- LETTERS TO THE EDITOR
123(2008); http://dx.doi.org/10.1121/1.2839134View Description Hide Description
The recent paper by Ona et al. [J. Acoust. Soc. Am.121, EL145–EL150] compared avoidance reactions by herring (Clupea harengus) to a traditional and a “silent” research vessel. Surprisingly, the latter evoked the strongest avoidance, leading to the conclusion that “candidate stimuli for vessel avoidance remain obscure.” In this Comment, it is emphasized that the otolith organs in fish are linear acceleration detectors with extreme sensitivity to infrasonicparticle acceleration. Near-field particle motions generated by a moving hull are mainly in the infrasonic range, and infrasound is particularly potent in evoking directional avoidance responses in several species of fish. The stimuli initiating vessel avoidance may thus include infrasonicparticle acceleration.
123(2008); http://dx.doi.org/10.1121/1.2872516View Description Hide Description
By placing a vertical array in an ambient noise field and forming an upward and a downward beam one obtains two time series which can be cross correlated to reveal a subbottom profile of the seabed [Siderius et al., J. Acoust. Soc. Am.120, 1315–1323 (2006)]. Here the cross-correlation approach is applied to the location in range and bearing of a point target. An experiment was designed using floats and weights mounted (and dismounted) on the same cable as the vertical array. Careful measurements were made of the location of all likely floats, ballast weights, array terminations, and so on. After suitable coherent averaging, peaks were seen at delays (correlation offsets) agreeing with the reflector positions and were shown to be absent when reflectors were removed. A trivial extension of the theory developed in Harrison and Siderius [J. Acoust. Soc. Am.123, 1282–1296 (2008)] is used to explain the rough amplitudes of the reflections. The approach differs from “acoustic daylight” principally in having a capability to determine a target range.
123(2008); http://dx.doi.org/10.1121/1.2836745View Description Hide Description
This letter investigates the effectiveness of various configurations of reference sensors for feedforward active control systems in vehicles using unconstrained frequency domain optimization. The results from a model problem are based on a fully coupled analysis between the vibration of a car panel and an enclosed acoustic field. These suggest that with correct locations, only a small number of microphones or accelerometers are needed to give good overall performance, despite many uncorrelated primary disturbances being present. Similar results are predicted from road test data.
A comparison of statistically optimized near field acoustic holography using single layer pressure-velocity measurements and using double layer pressure measurementsa)123(2008); http://dx.doi.org/10.1121/1.2875308View Description Hide Description
Statistically optimized near field acoustic holography (SONAH) is usually based on the assumption that all sources are on one side of the measurement plane whereas the other side is source free. An extension of the SONAH procedure based on measurement with an array of pressure-velocity probes has recently been suggested. An alternative method uses a double layer array of pressuretransducers. Both methods make it possible to distinguish between sources on the two sides of the array and thus suppress the influence of extraneous noise and reflections coming from the “wrong” side. This letter compares the two methods.
123(2008); http://dx.doi.org/10.1121/1.2875365View Description Hide Description
The present study investigates the decay of pitch memory over time. In a delayed pitch comparison paradigm, participants had to memorize the pitch of a Shepard tone, with silent, overt, or without any rehearsal. During overt rehearsal, recordings of the rehearsing were effectuated. Performance was best for silent rehearsal and worst for overt rehearsal. The differences, although partially significant, were not marked. The voicepitch during overt rehearsal was compatible with a random walkmodel, providing a possible explanation of why rehearsal does not improve the retention of the pitch trace.