bluuebunny/crossref_metadata_2025 huggingface dataset:
Research into quality assessment methods for anechoic chambers
Authors: Babineau Francis , Tinianow Brandon
Published: July 2012

The goal in qualification testing for any anechoic or hemi-anechoic chamber is to define a volume within which acoustic measurements can be performed accurately in a free-field condition. In this study, both commonly accepted and novel techniques are employed to assess the acoustical performance of a hemi-anechoic chamber and ultimately its relevancy for qualified testing. Two recognized international test methods are discussed, as well as various alternate methods. The alternate methods include variations on the existing standards, utilizing acoustic intensity measurements and using an alternate sound source. The alternate sound source more closely approaches actual sound power testing conditions, in that it does not have a well-defined acoustic center. Considerations for performance assessment include impact on sound power measurements, ease of assessment, and comparisons of results to those of accepted methods. Recommendations for improvements to contemporary assessment techniques as well as future work will also be presented.
A comparison of two methods for the evaluation of prominent discrete tones: Phase 3
Authors: Balant Anne C. , Hellweg Robert D. , Nobile Matthew
Published: July 2012

This paper presents results of Phase 3 of the study of prominent discrete tones by the Inter Committee Working Group (ICWG) from Information and Technology Equipment (ITTE). Progress and earlier results were reported at INTER-NOISE 99, the 139th Meeting of the Acoustical Society of America, and INTER-NOISE 2000. Phase 3 is a round robin involving 40 signals (some from ITTE products and some artificial sounds), which were recorded and distributed to participants as .wav files. Each of several ITTE company laboratories determined the objective tone-to-noise ratios and prominence ratios of the signals and/or provided subjective ratings. The paper presents comparisons of the objective and subjective ratings from the different laboratories. The relative success of the two objective methods in predicting the subjective ratings is discussed, as are the underlying issues and recommendations of the task group.
Creating noise sources for rotorcraft and aircraft noise simulation models
Authors: Plotkin Kenneth J.
Published: July 2012

Modern computing power has made noise simulation models, i.e., prediction of actual time histories of sound levels, practical. Switzerland uses its FLULA model for airport noise contours. NASA’s new RNM rotorcraft model uses simulation to address the complexities of rotorcraft noise. The Wyle/USAF NMSIM fixed-wing model has been used to address significant effects associated with complex terrain. A requirement for this type of model is the three-dimensional noise source properties of the aircraft being analyzed. This information is generally extracted from fly-over noise tests. Because noise is needed on a complete sphere (or at least a hemisphere), parts of the noise sphere are associated with long propagation distances and/or grazing incidence to measurement positions. This paper reviews the practical problems associated with turning fly-over measurements into source models. Examples from experience with RNM and NMSIM are presented.
Talker voice and similarity affect lexical neighborhoods
Authors: Zimack Liza K. , Sawusch James R. , Measer Kathleen M. , Luce Paul A. , Newman Rochelle S.
Published: July 2012

Words that are similar to a syllable can influence listeners perception of phonemes in the syllable. Known as the lexical neighborhood effect, this has been shown to be robust, but vary in magnitude across talkers. In previous studies [L. Zimack and J. Sawusch, J. Acoust. Soc. Am. 107, 2918 (2000)], series of nonword syllables were tested in two voices. In one voice, an effect of neighborhood on phonetic perception was clearly found. In the other voice, this effect was absent. The pattern of results suggested that there may be differences in the composition of neighborhoods across different talkers. New studies have explored acoustic–phonetic factors in voices that may underlie this variation. The influence of neighborhood has been examined across syllables from 10 talkers. Measurements of syllable duration, speaking rate, and formant frequencies have also been made for these 10 talkers. Across the talkers, there is variation in the effect of neighborhood on phoneme perception. These data will be presented along with acoustic measurements of vowel spaces and other qualities that may influence the similarity of phonemes and words to one another and thus alter the influence of neighborhood upon perception. [Work supported by NIDCD Grant R01DC00219 to SUNY at Buffalo.]
Lexical tone in spoken word recognition: A view from Mandarin Chinese
Authors: Lee Chao-Yang
Published: July 2012

In Mandarin Chinese, segmentally identical words are distinguished by lexical tones, which are realized as distinct fundamental frequency patterns over a syllable. Since tone is used phonemically in this language, the question arises of whether tone is implicated in lexical processes in the same way as segmental structure. Three experiments evaluated the role of Mandarin tones in lexical activation and competition. The form and mediated priming experiments showed that Mandarin listeners exploited lexical tone on-line to disambiguate monosyllabic words that were segmentally identical but tonally distinct. Furthermore, acoustic similarity between tones modulated the magnitude of priming and generated opposite priming patterns between the two priming experiments. The interplay of lexical activation and inhibition, based on a neural network model of lexical access, was invoked to account for the dissociation. The gating experiment showed that more acoustic input was needed to recognize words with tonal minimal pairs, indicative of lexical competition. In conclusion, this study showed that lexical tone in Mandarin Chinese participates in lexical processes, and that the mapping of tonal information onto the lexicon is based on acoustic similarity between tones. The author thanks Sheila Blumstein, Philip Lieberman, James Morgan, Peter Eimas, and Molly Homer for their helpful comments.
Development of prevocalic, intervocalic, and postvocalic /r/ in young American children
Authors: McGowan Richard S. , Nittrouer Susan , Manning Carol
Published: July 2012

The development of children’s /r/ production is the subject of a current investigation of a longitudinal database of children’s speech. Nine children were recorded interacting with a parent in approximately 2-month intervals from the age of about 15 months to the age of about 31 months. It would be expected that many of these children would not produce /r/ in an adult manner [e.g., M. M. Vihman and M. Greenlee, J. Speech Hear. Res. 30 (1987)], but the properties of children’s production of /r/ as a function syllable position and the production of r-colored vowels has not been examined closely. We have examined two children from this database for their ability to produce /r/ and r-colored vowels in various syllable positions. These children more readily produce postvocalic /r/ and r-colored vowels than they produce prevocalic /r/. Further, it may be that practice with intervocalic /r/ may help in future productions of prevocalic /r/’s. These observations will be quantified using formant frequency and amplitude measures and compared with the productions of /r/ by other children in the database.
Infant sensitivity to lexical neighborhoods during word learning
Authors: Hollich George J. , Jusczyk Peter W. , Luce Paul A.
Published: July 2012

Competition from existing lexical items that share similar phonotactic and phonetic properties could inhibit a child’s ability to encode new items. Two studies are reported that examine infant’s abilities both to detect the similarity among these ‘‘lexical neighbors,’’ words that differ by a single phoneme, and to learn a referent for a novel neighbor after an exposure to a high number of these similar sounding words. In study 1, 15-month-old infants exhibited a novelty preference for a neighborhood prototype after being familiarized with twelve lists of twelve neighbors. This suggests that infants are capable of detecting neighborhood similarity among words. In study 2, 17-month olds were tested on their ability to learn the referents of two novel prototypes after being exposed to their respective lexical neighbors. In the high-density condition, six lists of twelve neighbors were used. The low-density condition consisted of six lists of three neighbors plus nine filler items. Results indicated that word learning was significantly better in the low density condition, both in overall looking times and in infant reaction times to the targeted word. These results fit well with current models of spoken language recognition that suggest a competitive effect for words arising from dense lexical neighborhoods.
Auditory-visual context effects on the perception of voicing
Authors: Norrix Linda W. , Keintz Connie
Published: July 2012

Perception of an auditory continuum can be changed by a preceding visual context [K. Green and L. Norrix, in press, JEP: HPP]. This study examines if a visual context for /l/, as in /abla/, influences the voicing distinction for an auditory /aba/-/apa/ continuum. Voice onset time (VOT) and F1 onset frequency were measured during production of /aba/, /apa/ (singleton conditions) and /abla/, /apla/ (cluster conditions). Findings indicate longer VOTs in /apla/ compared to /apa/ and lower F1 onset frequencies for the cluster compared to singleton conditions. An auditory-only (AO) continuum (/aba/–/apa/) was created and presented to listeners for identification. In an auditory-visual (AV) condition each auditory token was paired with a face saying /abla/ and presented for identification. If subjects use knowledge about coarticulation and its effects on VOT during production, then they should make more /b/ responses in the AV compared to AO condition. In contrast, if they recover F1 information from the visual articulation, then more /p/ responses should be obtained. Findings indicate more /p/ responses in the AV compared to AO condition, suggesting that perceivers are recovering information from visual articulations (perhaps tongue height) rather than using stored knowledge about coarticulatory effects on VOT. [Work supported by NSF.]
Analysis filterbank with arbitrary frequency and bandwidth using a multitaper technique
Authors: Suzuki Ryuji , Buck John R. , Costa Antonio H.
Published: July 2012

Acoustical signals are often analyzed for power spectral density. The computational efficiency of the fast Fourier transform (FFT) for the short-time Fourier transform (STFT) is attractive in many contexts, but some applications require nonuniformly spaced analysis frequencies with different bandwidths. Two common examples are the mel frequency scale for speech signals and the constant Q or logarithmic frequency scale analysis of musical signals. These analyses are usually implemented with polyphase filterbanks, wavelets, or an ad hoc technique. This research presents a new method that allows arbitrary analysis frequencies and variable bandwidths. The method is based on the multitaper approach from nonparametric spectral estimation. Consequently, this method preserves the benefits of the multitaper approach, namely improved bias and variance properties when compared with the regular STFT-based approach. The multitaper method requires O(NM) computations, where N is the data segment length and M is the number of analysis frequency channels. This is the same order of growth exhibited by the straight discrete Fourier transform with the same N and M. [Work supported by NSF Ocean Sciences.]
Species identification of pelagic fish schools using acoustic descriptors and ancillary information
Authors: Lawson Gareth , Barange Manuel , Freon Pierre
Published: July 2012

It is shown that schools of similarly sized and behaving pelagic fish species can be accurately identified to species over a large spatial area, on the order of the broad spatial-scales typical of standard assessment surveys, and over a time-span of three years. Acoustic measurements of morphometric, energetic, and bathymetric features of anchovy, sardine, and round herring schools were extracted using commercially available software from acoustic data collected by a conventional single-frequency narrow-band echosounder during trawling operations of pelagic stock surveys of the South African continental shelf (November 1997, 1998 and 1999). Discriminant function analysis of 18 descriptors of the 214 schools for which the species composition was satisfactorily determined by trawl samples indicated that schools could be correctly identified to species in 88.3% of all cases (94.9% for anchovy, 82.6% sardine, 82.6% round herring). The three species were differentiated primarily on the basis of school bathymetric position and backscattered energy. Including ancillary information (latitude, longitude, sea surface temperature, bottom depth, and time of day) in analysis improved the accuracy of school identification to 94.9%, since such variables allowed discrimination on the basis of interspecific differences in habitat use, as well as in schooling behavior. a)Currently at MIT/Woods Hole Joint Program.
Methods for detecting bubbles and monitoring cavitation activity; a report from Working Group 22 of Standards Committee S1
Authors: Nyborg Wesley L.
Published: July 2012

Few liquids or solids are homogeneous; most contain cavities filled with air or other gas. They may be large or small, desirable or harmful. In diagnostic medicine, small gas-containing particles are introduced into the circulation as contrast agents to improve ultrasound images. In lakes and oceans, bubbles produced at the surface present difficulties for sound propagation. In industries gaseous phase is sometimes desired in manufactured products, but unwanted gas bubbles can be a serious problem. Exposing cavities to sound produces a complex panoply of activity which includes simple breathing oscillations, shape oscillations, high-speed travel, jet formation, dramatic implosions, fragmentation, bubble growth and microstreaming. Mechanical stresses and chemicals produced by acoustic cavitation are capable of causing a host of physical, chemical and biological effects which can be desired, as in sonic cleaning or sonoporation, or harmful if unwanted chemical action or solid erosion is produced. The ASA Committee on Standards established a working group to prepare a technical report dealing with the many techniques which have been used to characterize bubbles and monitor cavitation activity. In this report, 25 techniques are described. Principles of operation are explained and applications discussed for each of these. 2491,2492
Bio-inspired acoustic sensors based on artificial stereocilia
Authors: Noca Flavio , Hoenk Michael , Hunt Brian , Koumoutsakos Petros , Walther Jens , Werder Thomas
Published: July 2012

A unique, biologically inspired acoustic transducer based on artificial stereocilia is being developed. This transducer will enable directional sensitivity and miniaturization of acoustic sensors while enhancing sensitivity, ultimately leading to revolutionary advances in acoustic detection and signal processing. The similarities between natural stereocilia and the proposed transducer array could allow for the first time the fabrication of an artificial cochlea that relies on biologically inspired signal-processing techniques. Other applications, such as measuring sounds generated by moving micro-organisms and nanoscale biological events (metabolic flows), may be enabled by this novel transducer. Finally, artificial stereocilia (functioning as actuators instead of sensors, analogous to stridulatory pegs in insects) will be capable of generating acoustic signals for applications in active acoustic instruments such as sonar. Before these advantages can be realized, fundamental developments are required in the design and fabrication of a transducer based on artificial stereocilia arrays. The potentially revolutionary nature of this transducer is being demonstrated by fabricating and characterizing acoustic sensors based on recently produced carbon nanotube arrays.
A surface acoustic wave hygrometer for high-resolution measurements of atmospheric humidity
Authors: Hoenk Michael E. , Cardell Greg , Noca Flavio , Watson Robert K.
Published: July 2012

Weather and climate depend on atmospheric phenomena at all scales, from large-scale atmospheric circulation to microphysical processes. In this talk, a surface acoustic wave (SAW) hygrometer developed at JPL for high-resolution measurements of atmospheric humidity will be discussed. Flight tests of an early prototype on the NASA DC8 showed more than an order of magnitude faster response than chilled-mirror hygrometers. In 1998, a 1-kg reference radiosonde based on the SAW hygrometer was flown on a small balloon to an altitude of 44000 feet, while a mobile ground station recorded telemetered data containing high-resolution measurements of humidity, pressure, temperature, and GPS position. Later in 1998, the SAW hygrometer was deployed on the NASA DC8 to measure humidity in Atlantic hurricanes. In 1999, the SAW hygrometer recorded humidity in the test flight of NASA’s Helios unpiloted aircraft. Currently, this instrument is being modified for incorporation into a hand-held instrument for monitoring environmental humidity on the space station. [The research described in this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, and was jointly sponsored by the National Aeronautics and Space Administration, Earth Science Enterprise, Space Science Enterprise, and Human Exploration and Development of Space Enterprise.]
MEMS condenser microphone
Authors: Henning Peter J. , Storgaard-Larsen Torben
Published: July 2012

The measurement microphones of today are the results of almost 50 years of continuous optimization of production methods based on precision mechanics. Scientists have searched for new ways of measuring sound, which can reach the performance of the condenser microphone, but so far have not succeeded! However, applying new materials and production methods, the window of achievable specifications of condenser microphones can be widened. Combining the accuracy and reliability of silicon micro machining with the experience gained on traditional measurement microphones, unique new features can be added to the range of microphones. As a first result of such efforts, a new microphone unit, the multifield microphone, has been developed. The multifield microphone has a ‘‘flat’’ frequency response in all sound fields, i.e., pressure field, diffuse field, or free field (when the sound comes from different angles of incidence). This results in higher accuracy in most measurement situations, where the sound field is nonidealized.
Can soundscapes work as a moderator concerning noise annoyance?
Authors: Schulte-Fortkamp Brigitte
Published: July 2012

The evaluation procedure to detect and to analyze soundscapes in their meaning regarding noise annoyance measurement is a new step and a very complex procedure. Focusing on the interaction of people and noise, different aspects like the structure of urban areas, people living in those areas, architectural and social parameters designing those areas, and acoustical and visual parameters will be taken into account for analyses. Moreover socio-cultural- and lifestyle-related elements of soundscapes have to be discussed concerning the aspects of annoyance measurement which usually are focused on interference, disturbance, sources of annoyance, and predicting noise annoyance. Basically, in the discussion of both procedures it is questioned whether soundscapes can work as a moderator concerning annoyance. Detailed aspects may lead to the question of correlations between annoyance judgments and somatic processes, and what happens when people give an overall judgment on the degree of annoyance. Future research is needed to explore soundscapes moderating the judgment on life situation and noise sources.
The application of a noise-rating scale composed of hue-scale and LAeq on various kinds of noise sources for noise map
Authors: Furihata Kenji , Yanagisawa Takesaburo
Published: July 2012

In addition to reporting the results of measurements of existing environmental noise and the results of calculations of noise from projected activities, the application of color for representing in terms of noise zones may be useful (ISO 1996-2). Between color and noise, in spite of differences, there exists an interaction, although the connection between the visible and the audible expression is subjective. Subjectivity can in a given moment become objective, if one succeeds in unifying the visible and the audible. In the case of colored paper on a white background, the relation between the hue level expressing the psychological effect (annoyance) and LAeq(5min) (dB) of typical noise sources was discussed in a laboratory experiment. According to the obtained noise-rating scale, the seven-hue scale and LAeq(5min) are correlated well (r=0.874) as follows: white (value V9; not at all bothersome) ⇔ below 26 dB, light blue (hue 2.5B, value 8/chrome 4; not bothersome) ⇔ 26 to 37 dB, light green (2.5BG, 7/8; not too bothersome) ⇔ 37 to 49 dB, bright yellow (7.5YR, 7/14; a little annoying) ⇔ 49 to 61 dB, brown (10R, 4/8; annoying) ⇔ 61 to 70 dB, purple (2.5P, 4/10; very annoying) ⇔ 70 to 80 dB and red (5R, 5/14; extremely annoying) ⇔ over 80 dB.
Active control of low-frequency turbine exhaust noise
Authors: Walker Bruce , Hersh Alan , Celano Joseph , Ray Eldon
Published: July 2012

Gas turbine generators radiate noise from their exhaust stacks that contains substantial acoustical energy at very low frequencies. This kind of noise can result in community annoyance due to window rattling and other structural vibration excitation as well as disturb residents. Because of the long wavelengths of sound at these frequencies, typical duct sound absorbing treatments are inefficient, large and expensive. A research program was conducted to demonstrate the ability of a Helmholtz-resonator-based active noise control system to attenuate low-frequency noise in a heated exhaust stack. A unique thermal stratification concept was developed that successfully protected the sound sources from hot exhaust flue gases. The thermal stratification concept permitted the use of both conventional off-the-shelf JBL 18-in. electrodynamic actuators and custom-fabricated piezoceramic sound sources in the demonstration program. Test results showed that 14–22 dB of noise attenuation was achieved over the frequency range 20–32 Hz at flue temperatures between 80° and 1300°F.
Determination of sound pressure levels in situ using sound intensity measurements
Authors: Keith Stephen E. , Chiu Vincent , Krishnappa G.
Published: July 2012

Measurements of emission sound pressure levels of machinery require either specially defined test rooms or calculated corrections for the acoustic environment. In principle, it is possible to determine emission sound pressure levels from sound intensity measurements at specified work stations in any test environment if the requirements of background noise levels and field indicators are fulfilled. The draft international standard ISO 11205/CD specifies such a method. In this paper the accuracy of emission sound pressure levels using sound intensity measurements was examined for three small sources in three acoustic environments, an anechoic environment with loudspeakers to simulate background noise, an office environment, and a reverberant environment inside a stairwell. In the first two environments good measurement accuracies, within 1 dB, were obtained. Sound intensity measurements by pointing the probe towards the source were as accurate, and simpler than computation of the resultant intensity using three arbitrary orthogonal measurements. As predicted by field indicators, measurements in the stairwell gave unacceptable errors for all three sources.
Diagnostics of vibration excitation mechanisms for complex hydromechanical systems
Authors: Prokofiev Andrei B. , Lenchine Valeri V. , Shakhmatov Evgeniy V.
Published: July 2012

It is known that high-amplitude vibration can significantly impair reliability of technical tools. Sometimes it is difficult to identify the mechanism of vibration excitation in complex hydromechanical systems with many sources of oscillation. Simple frequency and correlation analysis does not provide all needed information. It is suggested to perform both usual vibration analysis in frequency domain and check out fluid-induced vibrations and conditions for auto-excitation caused by interaction of reciprocating mechanical parts and pulsing fluid. A case with an ammoniac compressor station is considered as an implication of the method. During the compressor station exploitation vibration has been observed with a frequency of 18.8 Hz that propagates through the system and exceeds the permitted level by 2.23 times. The frequency does not correspond to any known sources of oscillation for the system. The analysis showed that the back valve and attached pipes represent an auto oscillation contour that generates both low-frequency pulsation of fluid and mechanical vibration. It represented results of operational development of the compressor station, using the proposed technique that allowed the reduction of essential vibration of the system and generated noise.
The mufflers for exhaust valves of industrial equipment
Authors: Lenchine Valeri V.
Published: July 2012

The operating of exhaust valves of pneumatic cylinders and other pneumo-automatics causes impulse noise generation. Staff, working on half-automated conveyers and package lines, are often exposed to the high-intensity impulse noise, which is a reason for hearing loss. The design of a silencer for steady flow is well explored but there is not as much attention for an impulse noise attenuator. Moreover, mufflers for discharge valves of industrial equipment must meet additional requirements because an air exhaust emits broadband sound and an implication of mufflers with essential aerodynamic drag results in an operational disorder for pneumo-automatics. The long lifetime and simple maintenance are also significant for a consumer. The muffler’s model takes into account an attenuation performance, calculation of a silencer pressure drop, and prediction of mass and size of the device that allows us to work out multi-criteria optimization tasks. There are considered peculiarities of impulse noise muffler design for the packaging pneumatic automates. The mufflers have low aerodynamic drag, are easy to install, inexpensive, and reliable. They provide the best acoustical performance for frequencies 500–4000 Hz. The comparison of effectiveness is represented for the different silencers. There are given examples of successful implementation of the mufflers in industry.
Noise impact from motor racing events
Authors: de Leo Alberto , Giuliani Franco , Fabozzi Concetta
Published: July 2012

The new Italian rules about noise pollution (General Law no. 447/95 and subsequent decrees) have caused the necessity of carrying out some measurement campaigns in order to observe the acoustic effects of various events and their interaction with territory and population. One of the research studies carried out by ANPA (Italian Agency for Environmental Protection) has dealt with a cognitive survey in motor racing sites and the noise impact that such infrastructures have on the surrounding environment. Measures have been done in and around motordromes, of which two are used for F1 races and one for motorcycles races; they differ from one another for territory orography, wind conditions and outskirts urbanization.
Why can spherical harmonics be used to describe the sound field generated by nonspherical sources?
Authors: Rayess Nassif E. , Wu Sean F.
Published: July 2012

The spherical harmonics in conjunction with the spherical Hankel functions form a complete set of spherical basis functions, which can fully describe the radiated sound field from a vibrating object. The vibrating object itself need not be spherical as long as the exterior region is beyond a minimum sphere that completely encloses the object. Such expansion solutions are not supposed to be valid inside the minimum sphere. However, experimental results [Rayess and Wu, J. Acoust. Soc. Am. 107] using the Helmholtz equation–least-squares (HELS) method [Wang and Wu, J. Acoust. Soc. Am. 102] have shown that a modified set of spherical basis functions can accurately describe the sound field well inside the minimum sphere. That modified set is obtained by Gram–Schmidt orthonormalization of the spherical basis functions with respect to the source surface. It is shown that the velocity fields corresponding to these modified basis functions form an orthogonal and complete set, which can uniquely describe the velocity field on the surface. The proof given in this paper will provide a solid foundation for the establishment of the HELS method as a potentially viable noise diagnostic tool. [Work sponsored by NSF and Ford Motor Company.]
Determination of the optimal number of expansion terms in the HELS method
Authors: Lim Byoung-Duk , Wu Sean F.
Published: July 2012

The Helmholtz equation least-square (HELS) method has been proven to be an efficient way of reconstructing acoustic radiation from a vibrating structure [Wu, J. Acoust. Soc. Am. 107, 2511–2522 (2000)]. In this method, the optimal number of expansion terms is determined by a heuristic method of searching the minimum–norm errors of the reconstructed acoustic pressures with respect to the measured data. While this approach works, it is time consuming. In this paper, a new method of a priori determination of the optimal number of expansions is developed based on the eigenvalue analysis of the measured information. Assuming a Gaussian white measurement noise, the hypothesis of equal noise eigenvalues is tested based on the statistical properties of the eigenvalues. This hypothesis test yields an upper bound of the optimal number of expansions in general. Also developed is a method for testing the correlation coefficients after eliminating some principal components, which gives a lower bound of the optimum number of expansions. Since the curve of minimum–norm errors in the previous work shows local minima when the number of terms is squares of the integer, the range produced by the present method leads to only a few candidates for the optimal number of expansions. Examples of reconstructing the radiated acoustic pressure field from a vehicle front end using the optimal number of expansion terms thus obtained are demonstrated in parallel with the results of the a posteriori method discussed by Wu. [Work supported by NSF.]
Vibro-acoustography of small spheres
Authors: Chen Shigao , Fatemi Mostafa , Greenleaf James F.
Published: July 2012

Vibro-acoustography is a method for imaging the acoustic energy emitted from objects in response to an oscillatory radiation force produced by two interfering focused beams of ultrasound [M. Fatemi and J. F. Greenleaf, Science 280, 82–85 (1998)]. To facilitate quantitative study, a model is presented that describes the behavior of an elastic sphere in two plane ultrasound waves of slightly different frequencies. The vibrating velocity and the resulting acoustic emission of the sphere at the difference frequency are derived from the radiation force and the impedance of the sphere. For small steel spheres in water, the velocity and emission are predicted to have a simple relationship with the difference frequency and the size of the sphere. Experiments on small stainless steel spheres of different size are carried out for a number of difference frequencies, with a laser interferometer to measure the velocity of the sphere and a calibrated hydrophone to measure the acoustic emission from the sphere. The experimental results fit the model description well. This means that vibro-acoustography may be useful in quantitative measurement.
New effects of laryngeal configurations on f0: Voiceless stops in Korean
Authors: Oh Sunyoung
Published: July 2012

Korean has three sets of voiceless stops in word-initial position which are distinctive from one another in terms of laryngeal adjustments: lenis unaspirated, fortis unaspirated, and aspirated [P. Ladefoged and I. Maddiedson, 47–101 (1996)]. It has been observed that, in Standard Korean, the aspirated stops have higher f0 value than the fortis stops, while both stops have higher f0 value than the lenis stops [D. Silva, 11–34 (1998)]. It could be argued that this indicates a universal correspondence between laryngeal configurations for voicing and pitch—at least within Korean. However, the current paper reveals a different observation. In South Kyengsang dialect in Korean, little difference is found in the f0 value between the aspirated and the fortis stops, while the f0 of the lenis stops is relatively lower, similar to Silva’s (1998) finding. A total of 600 tokens, by five speakers, were recorded and digitized, then analyzed using Macquirer software for pitch tracking. The results show that the f0 following the fortis stops are consistently higher than that of Standard Korean, regardless of the place of articulation, and the higher f0 of the fortis stops patterns with the lower f0 of the lenis stops among speakers.
Effects of speaking rate on vowel formant trajectories
Authors: Berry Jeff , Weismer Gary
Published: July 2012

The effects of speaking rate and vowel context on formant frequencies have traditionally been assessed by analyzing the variation in some operationally defined ‘‘target’’ frequency value. The use of a single frequency value to describe the behavior of a formant has proven useful for distinguishing among vocalic nuclei and identifying ‘‘target undershoot’’ effects of speaking rate. We have, however, only limited understanding of the characteristic effects of speaking rate change on formant trajectories. In our work, analysis of more complete representations of the time-varying changes in formant frequencies throughout vocalic nuclei have revealed patterns of formant change across speaking rates that differ qualitatively and quantitatively between speakers. These data suggest speaker-specific strategies for accomplishing speaking rate change. We have also observed that the acoustic effects of rate change within speakers differ qualitatively and quantitatively between different ranges of the vowel duration continuum. Thus, the acoustic effects of small changes in speaking rate at speaking rate extremes are not comparable to quantitatively identical changes at habitual rates. Since changes in speaking rate are commonly thought to correspond with changes in the overlap of neighboring articulatory gestures, these findings are pertinent to modeling coarticulation. [Work supported by NIH DC 0149-10.]
On the correlation between articulatory and acoustic data
Authors: Jiang Jintao , Alwan Abeer , Keating Patricia , Bernstein Lynne E. , Auer Edward
Published: July 2012

In J. Acoust. Soc. Am. 107, 2904 (2000), we investigated the correlations between external facial movements, tongue movements, and speech acoustics using a database of consonant–vowel syllables spoken by one female and two male talkers. The intelligibility of the talkers, based on visual information, was judged by hearing-impaired individuals. In this study, we extend the analysis to two sentences and a fourth talker (female); each sentence was repeated five times. Two of the talkers (one male and one female) had high-intelligibility ratings while the other two had low ratings. A Qualisys (optical motion capture system) and an EMA system were used to characterize orofacial and tongue movements, respectively. The articulatory and acoustic data streams were recorded simultaneously and aligned. Acoustic features were represented by line spectral pairs. A multilinear regression technique was applied to quantify the correlation between the data. A universal estimator was obtained with training data, using a jack-knife approach, and then applied to the test data. Correlations results were speaker dependent, and, on average, the highest correlations were between the optical and EMA data. Detailed results, including a comparison between the results for CVs and sentences, and implications will be discussed. [Work supported in part by NSF KDI award 9996088.]
A study of compensation for a labial perturbation of the vowel /u/ using an area function model of the vocal tract
Authors: Story Brad H.
Published: July 2012

This study reports on the ability of an area function model of the vocal tract [Story and Titze, J. Phonetics 26, 223–260 (1998)] to compensate for a labial perturbation. The area function model, which consists of a neutral shape and two weighted orthogonal shaping patterns (modes), is first configured for a typical production of /u/. An effective lip tube based on the labial perturbation experiment reported by Savariaux et al. [J. Acoust. Soc. Am. 98, 2428–2442 (1995)] is then imposed on the area function model (by forcing the lip section to be a constant cross-sectional area). Frequency responses are computed for both the normal and the perturbed shapes. Next, an attempt was made to vary the weighting values for the two shaping patterns of the area function model so that the first two formants were moved back toward their unperturbed frequency locations. The result was that weighting values can be determined that do move the formants in the appropriate direction for compensation. Additionally, the resulting area function shows characteristics similar to those presented by Savariaux et al.; that is, a movement of the constriction location posteriorly and a widening of the anterior portion of the front cavity. [Work supported by NIH R01-DC04789-01.]
Electropalatographic and acoustic measures of adaptation to palatal perturbation
Authors: Aasland Wendi A. , Baum Shari R. , McFarland David H.
Published: July 2012

The present investigation examined adaptation to a palatal perturbation in [s] production, as reflected in both electropalatographic (EPG) and acoustic measures. The goal was to explore the development of compensatory motor programs during the production of individual fricative segments, as well as over a 1-h period of focused practice. Thirty repetitions of the syllable [sa] were produced at each of five time intervals (times 0, 15, 30, 45, and 60 min) by a speaker wearing a specially designed pseudopalate with a 6 mm buildup of acrylic at the alveolar ridge. At times 0 and 60, baseline measures of [sa] production with a thin pseudopalate and with no palate in place were also recorded to characterize unperturbed articulation. Acoustic analyses focused on centroid frequencies for the [s] productions, while a wide range of EPG analyses were conducted including measures of groove length and width, location and duration of maximum constriction, and variability in tongue-palate contact patterns throughout the fricative production. Preliminary analyses indicate a high degree of variability throughout the practice period. Results are discussed in relation to the development of adaptive articulatory programs in speech motor control and the articulatory configurations necessary for adequate [s] production. [Work supported by NSERC.]
SAX99: An experiment in high-frequency sediment acoustics
Authors: Thorsos Eric I.
Published: July 2012

In the fall of 1999, ‘‘SAX99’’ (for sediment acoustics experiment—1999) was performed at a site 2 km from the shore on the Florida Panhandle in water 18–19 m in depth. The seafloor sediment was medium sand, and acoustic frequencies were mainly in the 10–300-kHz range. A wave-induced ripple field was present at the site. The main goals in SAX99 were to quantify acoustic backscattering from the sediment, acoustic penetration into the sediment (above and below the critical angle of 30 deg), and acoustic propagation within the sediment. Extensive environmental characterizations were made at the experiment site. Quantities that enter into a Biot model description of the sediment were measured. Sediment variability was measured to centimeter scales, giving the most complete coverage for the frequency range of 10–50 kHz. An overview of the entire SAX99 measurement program will be given. The range of acoustic measurements will be briefly described, as well as the scope of measurements of the seafloor physical properties and of biological processes within the sediment and the water column. Initial results of this work will be described in separate papers. [Work supported by ONR.]
Applied Physics Laboratory participation in SAX99: Experiment design and execution
Authors: Williams Kevin L. , Jackson Darrell R. , Tang Dajun , Thorsos Eric I.
Published: July 2012

The main goals of the APL program in SAX99 were to measure and improve our ability to model acoustic propagation within, high-frequency backscattering from, and penetration into sand sediments. To prepare for these measurements, new equipment and experimental procedures were developed. For the penetration studies, simulations were used extensively to guide the experiment design in order to ensure that the measurements would be useful for addressing our goals. Illustrations will be given of how simulations were used to support the experiment design. The APL experimental equipment used in SAX99 will be described, and the experimental procedures will be presented. Finally, the resulting data set will be summarized. [Work supported by ONR.]
Subcritical acoustic scattering across a rough fluid–solid interface—laboratory experiment and perturbation theory model
Authors: Mellema Garfield R. , Ewart Terry E. , Williams Kevin L.
Published: July 2012

Several mechanisms have been proposed by which an incident acoustic wave could be coupled into the ocean floor at angles below the compressional critical angle. Recent observations of acoustic transmissions from water into sediment with arrival times and amplitudes inconsistent with the refractive compressional path have been interpreted as the excitation of a Biot slow wave in the sediment. Another hypothesis attributes the observed signals to scattering at the rough water-sediment interface. A third entails scattering of evanescent waves by volume inhomogeneities in the sediment. The existence of multiple hypotheses, each of which could account for the received energy, invited further investigation. A series of well-controlled laboratory measurements were made and compared with the results of a first-order perturbation theory model in order to evaluate the accuracy of the rough interface hypothesis. The experimental measurements of transmission through adjacent flat and rough interfaces show good agreement with the results of the numerical model, giving clear evidence of subcritical penetration in an environment incompatible with the requirements of the Biot slow wave and volume scattering hypotheses.
Velocity dispersion in water-saturated granular sediment
Authors: Stoll Robert D.
Published: July 2012

When the Biot theory is applied to problems in sediment acoustics, significant velocity dispersion is predicted over a specific frequency range that depends on the pore-fluid mobility (permeability). This dispersion, and the associated nonlinear variation of attenuation with frequency, affects the reflection and transmission characteristics of the water–sediment interface, particularly at low grazing angles. Low-frequency velocity measurements taken during the ONR SAX99 experiments, when considered together with the high-frequency data, verify the existence of this dispersion. This result has important implications in the choice of critical angle and the interpretation and extrapolation of velocity and attenuation data taken at high frequencies. [Work supported by ONR, Code 321OA.]
Sediment acoustic backscattering during SAX99: Measurements and models
Authors: Williams Kevin L. , Jackson Darrell R. , Tang Dajun , Thorsos Eric I.
Published: July 2012

During the SAX99 experiment, acoustic backscattering measurements were made at frequencies from 20 to 300 kHz as a function of grazing angle. The results from these acoustic measurements will be presented and compared with backscattering models that use the environmental measurements of other SAX99 researchers as input. In the 20–50-kHz range these comparisons indicate that surface roughness plays a dominant role in acoustic backscattering with a very distinctive reduction in backscattering at grazing angles above the critical angle of the sediment. Above 50 kHz this critical angle feature is less evident. Possible reasons for this change with frequency will be discussed. The backscattering models used here were originally developed for frequencies from 10 to 100 kHz. SAX99 data give some indication that further modeling is needed above 100 kHz. [Work supported by ONR.]
The small slope approximation for acoustic scattering from a rough interface between a fluid and a fluid-saturated porous solid
Authors: Fetche Cristina , Broschat Shira L. , Yang Taiqian
Published: July 2012

The small slope approximation, introduced by A. G. Voronovich in the 1980s, gives a systematic expansion in terms of a generalized surface slope. Previous numerical studies indicate that the lowest-order term provides a reasonably accurate approximation for a number of different problems of practical importance. In this work we consider the small slope approximation for acoustic scattering from a rough interface between a fluid and a fluid-saturated porous solid in the context of Biot theory. Biot theory is of continued interest in the study of sediment acoustics; it predicts a slow compressional wave in the fluid-filled porous medium in addition to the conventional compressional and shear waves found in an elastic solid. The lowest-order small slope approximation is derived for Biot theory, and an expression for the bistatic scattering cross section is presented for plane-wave scattering from a randomly rough interface between a fluid and a fluid-saturated porous solid. Numerical results for the scattering strength are discussed for both the small slope and perturbation methods. [Work supported by ONR.]
Acoustics of a remodeled historic building
Authors: George Ballard W.
Published: July 2012

An acoustical study was performed for a historic San Francisco industrial building being remodeled for office, restaurant, and exhibit use. Challenges involving restoration ground rules included open beam construction with no use of ceilings. Flooring is proposed to be hardwood. Damped plywood was recommended to be used in flooring assemblies to enhance airborne and impact sound insulation performance. The building is across the street from the newly opened Pac tel baseball park for the San Francisco Giants. Accordingly, exterior noise sources included both automobile and bus traffic and the various sounds associated with baseball games. Sound measurements were taken at the 3 Com Park on Candlestick Point as an aid in predicting the sound levels associated with the new park. The acoustical study addressed the restaurants and exhibit spaces on the lower floors, the separating flooring assemblies between each level, and the sound ‘‘delivered’’ by ducting, and otherwise transmitted, to the future tenant spaces. Comments are given on the ‘‘soundscape’’ considerations associated with the various spaces of the lower floors of the building.