Volume 138, Issue 1, July 2015
- jasa express letters
- animal bioacoustics
- architectural 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:
- JASA EXPRESS LETTERS
138(2015); http://dx.doi.org/10.1121/1.4921746View Description Hide Description
The spatial variation in vector acoustic intensity has been calculated between 100 and 3000 Hz near a high-performance military aircraft. With one engine of a tethered F-22A Raptor operating at military power, a tetrahedral intensity probe was moved to 27 locations in the geometric near and mid-fields to obtain the frequency-dependent intensity vector field. The angles of the maximum intensity region rotate from aft to sideline with increasing frequency, becoming less directional above 800 Hz. Between 100 and 400 Hz, which are principal radiation frequencies, the ray-traced dominant source region rapidly contracts and moves upstream, approaching nearly constant behavior by 1000 Hz.
138(2015); http://dx.doi.org/10.1121/1.4922365View Description Hide Description
This study examined the benefit of a pretrial cue, a preview of the signal, on children's (5–10 years) and adults' detection of a 1000-Hz pure-tone signal in a broadband noise or a random-frequency, two-tone masker. No cuing effect was observed with the noise masker, regardless of listener age. In contrast, all but one adult benefited from the cue with the two-tone masker (average = 9.4 dB). Most children showed no cuing effect (average = 0.1 dB) with the two-tone masker. These results suggest that, unlike adults, the provision of a pretrial cue does not promote frequency-selective listening during detection for 5- to 10-year-olds.
138(2015); http://dx.doi.org/10.1121/1.4922364View Description Hide Description
The development of ambulatory voice monitoring devices has the potential to improve the diagnosis and treatment of voice disorders. In this proof-of-concept study, real-time biofeedback is incorporated into a smartphone-based platform that records and processes neck surface acceleration. The focus is on utilizing aerodynamic measures of vocal function as a basis for biofeedback. This is done using regressed Z-scores to compare recorded values to normative estimates based on sound pressure level and fundamental frequency. Initial results from the analysis of different voice qualities suggest that accelerometer-based estimates of aerodynamic parameters can be used for real-time ambulatory biofeedback.
138(2015); http://dx.doi.org/10.1121/1.4922366View Description Hide Description
Speech screening of sibilant fricative phonemes is an important tool for oral health care. Nevertheless, screening as a function of quantitative geometrical markers is mostly limited to teeth features whereas the minimum area of the narrowed air passage upstream from the tooth is known to be a key production feature. The minimum area is estimated from non-invasive aerodynamic measurements using a laminar flow model. The influence of viscid flow losses on the area estimation is shown to be negligible. Current data suggest that speech screening is most effective for phoneme /s/, which supports common practice in oral health care.
138(2015); http://dx.doi.org/10.1121/1.4922363View Description Hide Description
Older adults' normally adaptive use of semantic context to aid in word recognition can have a negative consequence of causing misrecognitions, especially when the word actually spoken sounds similar to a word that more closely fits the context. Word-pairs were presented to young and older adults, with the second word of the pair masked by multi-talker babble varying in signal-to-noise ratio. Results confirmed older adults' greater tendency to misidentify words based on their semantic context compared to the young adults, and to do so with a higher level of confidence. This age difference was unaffected by differences in the relative level of acoustic masking.
138(2015); http://dx.doi.org/10.1121/1.4922537View Description Hide Description
This work reports on the determination of the acoustic nonlinearity parameter, B/A, from measured sound speed data, in Fluorinert FC-43 at temperatures up to 381 K and pressures up to 13.8 MPa using the thermodynamic method. Sound speed was measured using Swept Frequency Acoustic Interferometry at 11 pressures between ambient and 13.8 MPa along 6 isotherms between ambient and 381 K. Second-order least-squares polynomial fits of measured sound speeds were used to determine temperature and pressure dependence. A room temperature B/A = 11.7 was determined and this parameter was found to increase by a factor of 2.5 over the temperature/pressure range investigated.
138(2015); http://dx.doi.org/10.1121/1.4922534View Description Hide Description
In a between-subject perception task, listeners either identified full words or vowels isolated from these words at F 0s between 220 and 880 Hz. They received two written words as response options (minimal pair with the stimulus vowel in contrastive position). Listeners' sensitivity (A′) was extremely high in both conditions at all F 0s, showing that the phonological function of vowels can also be maintained at high F 0s. This indicates that vowel sounds may carry strong acoustic cues departing from common formant frequencies at high F 0s and that listeners do not rely on consonantal context phenomena for their identification performance.
138(2015); http://dx.doi.org/10.1121/1.4922535View Description Hide Description
To expand national air transportation capabilities, NASA's Commercial Supersonic Technology Project is working to make supersonic flight practical for commercial passengers. As an aid in designing and certifying quiet supersonic aircraft, a noise metric is sought that will correspond to indoor annoyance caused by sonic booms, including the effects of indoor rattle sounds. This study examines how well several common aircraft noise metrics predict indoor annoyance based on the indoor and outdoor sound fields. The results suggest notional community annoyance models that include the effects of indoor rattle sounds.
Time reversal transfer: Exploring the robustness of time reversed acoustics in media with geometry perturbations138(2015); http://dx.doi.org/10.1121/1.4922623View Description Hide Description
In this letter, fundamentals of transferring a time reversal experiment between similar objects are discussed. The time reversal experiment consists of two steps: forward propagation, when a source excites the medium and a complex wave field is created, and back propagation, resulting in time reversal focusing. Here the procedure of performing the first step on one specimen and the second step on another is investigated. The theory of time reversal transfer is explained on an example of object shape variations. However, conclusions of the theoretical analysis are applicable universally. The feasibility of the proposed procedure is validated in experiments modeling conditions in practice.
138(2015); http://dx.doi.org/10.1121/1.4922763View Description Hide Description
The feasibility of using data derived replicas from ships of opportunity for implementing matched field processing is demonstrated. The Automatic Identification System (AIS) is used to provide the library coordinates for the replica library and a correlation based processing procedure is used to overcome the impediment that the replica library is constructed from sources with different spectra and will further be used to locate another source with its own unique spectral structure. The method is illustrated with simulation and then verified using acoustic data from a 2009 experiment for which AIS information was retrieved from the United States Coast Guard Navigation Center Nationwide AIS database.
138(2015); http://dx.doi.org/10.1121/1.4922765View Description Hide Description
This study investigated the impact of selective epithelial injury on phonation in an excised human larynx apparatus. With intact epithelium, the vocal folds exhibited a symmetrical vibration pattern with complete glottal closure during vibration. The epithelium was then enzymatically removed from one, then both vocal folds, which led to left-right asymmetric vibration and a decreased closed quotient. Although the mechanisms underlying these vibratory changes are unclear, these results demonstrate that some component of an intact surface layer may play an important role in achieving normal symmetric vibration and glottal closure.
138(2015); http://dx.doi.org/10.1121/1.4922767View Description Hide Description
This paper proposes a fault detection methodology for bearings using envelope analysis with a genetic algorithm (GA)-based adaptive filter bank. Although a bandpass filter cooperates with envelope analysis for early identification of bearing defects, no general consensus has been reached as to which passband is optimal. This study explores the impact of various passbands specified by the GA in terms of a residual frequency components-to-defect frequency components ratio, which evaluates the degree of defectiveness in bearings and finally outputs an optimal passband for reliable bearing fault detection.
138(2015); http://dx.doi.org/10.1121/1.4922762View Description Hide Description
This study analyzed Canadian French (CF) vowels /i y ø e ɛ o u a/ in word-final position. Of particular interest was the stability of /e-ɛ/; although some dialects of French have merged /e-ɛ/ to /e/ in word-final context, this contrast is maintained in CF. The present study investigated the stability of this contrast in various preceding phonetic contexts and in lexical vs morphological contrasts. Results showed that the contrast was maintained by all four speakers, although to varying degrees.
138(2015); http://dx.doi.org/10.1121/1.4922766View Description Hide Description
This investigation presents a method to engineer a metamaterial exhibiting the desired anisotropic wave behavior with the specific applications toward the dispersion suppression of elastic guided waves. In the proposed approach, effective anisotropic properties required for dispersion suppression were first determined. Then the slowness curves for the metamaterial were used to find the specific unit cell configuration through inverse design. When the metamateral layers were attached to the homogeneous waveguide, the target guided mode was shown to exhibit little dispersion. Detailed engineering procedures were given, and the direct numerical simulations were performed to confirm the effectiveness of the proposed approach.
138(2015); http://dx.doi.org/10.1121/1.4922764View Description Hide Description
Ultrasonic wave properties of human bone marrow obtained in the femur and tibia were measured using an ultrasound pulse technique. The measured frequency range was 4–10 MHz, and the temperature range was 30 °C–40 °C. The sound velocity was 1410 m/s, and the attenuation coefficient was 4.4 dB/cm at 36 °C (10 MHz). These values decreased with temperature. Site dependence and individual differences in elderly human bone marrow were negligible. The slopes of the attenuation coefficient were estimated by a power law. The values of the exponent n were 2.0 (30 °C–38 °C) and 2.3 (40 °C).
138(2015); http://dx.doi.org/10.1121/1.4923015View Description Hide Description
Poisson's ratio of an isotropic and free elastic plate is estimated from the polarization of the first symmetric acoustic zero-group velocity Lamb mode. This polarization is interpreted as the ratio of the absolute amplitudes of the surface normal and surface in-plane components of the acoustic mode. Results from the evaluation of simulated datasets indicate that the presented relation, which links the polarization and Poisson's ratio, can be extended to incorporate plates with material damping. Furthermore, the proposed application of the polarization is demonstrated in a practical field case, where an increased accuracy of estimated nominal thickness is obtained.
138(2015); http://dx.doi.org/10.1121/1.4921677View Description Hide Description
Previous work has shown that young children exhibit more difficulty understanding speech in the presence of speech-like distractors than do adults, and are more susceptible to at least some form of informational masking (IM). Yet little is known about how/when the “susceptibility” to linguistically-based IM develops. The authors tested adults, school-age children (aged 8 yrs), and preschool-age children (aged 4 yrs) on sentence recognition in the presence of normal speech, “jumbled” speech, and reversed speech distractors. As has been found previously with adults [e.g., Summers and Molis (2004). J. Speech, Lang. Hear. Res. 47, 245–256], children in both age groups showed a release of masking when the distractor was uninterpretable (reversed speech). This suggests that children already demonstrate linguistically-based IM by the age of 4 yrs.
138(2015); http://dx.doi.org/10.1121/1.4923268View Description Hide Description
Congenital amusia is a neuro-developmental disorder that may affect the processing of both music pitch and lexical tone. In the present study, the just-noticeable differences (JNDs) of tone pitch contour change were examined for three groups of Mandarin-native listeners: amusics with (tone agnosics) and without lexical tone difficulties (pure amusics), and matched controls. Tone agnosics showed significantly larger JNDs than normal controls, while pure amusics performed comparably with the controls. These results suggest that only those amusics with behavioral lexical tone deficits might be psychophysically impaired in pitch contour discrimination.
138(2015); http://dx.doi.org/10.1121/1.4922768View Description Hide Description
Asian Small-Clawed Otters (Aonyx cinerea) are a small, protected but threatened species living in freshwater. They are gregarious and live in monogamous pairs for their lifetimes, communicating via scent and acoustic vocalizations. This study utilized a hidden Markov model (HMM) to classify stress versus non-stress calls from a sibling pair under professional care. Vocalizations were expertly annotated by keepers into seven contextual categories. Four of these—aggression, separation anxiety, pain, and prefeeding—were identified as stressful contexts, and three of them—feeding, training, and play—were identified as non-stressful contexts. The vocalizations were segmented, manually categorized into broad vocal type call types, and analyzed to determine signal to noise ratios. From this information, vocalizations from the most common contextual categories were used to implement HMM-based automatic classification experiments, which included individual identification, stress vs non-stress, and individual context classification. Results indicate that both individual identity and stress vs non-stress were distinguishable, with accuracies above 90%, but that individual contexts within the stress category were not easily separable.
138(2015); http://dx.doi.org/10.1121/1.4922622View Description Hide Description
An individualized technical ear training method is compared to a non-individualized method. The efficacy of the individualized method is assessed using a standardized test conducted before and after the training period. Participants who received individualized training improved better than the control group on the test. Results indicate the importance of individualized training for acquisition of spectrum-identification and spectrum-matching skills. Individualized training, therefore, should be implemented by default into technical ear training programs used in audio production industry and education.