bluuebunny/crossref_metadata_2025 huggingface dataset:
An iterative algorithm for computing aeroacoustic integrals with application to the analysis of free shear flow noise
Authors: Margnat Florent , Fortuné Véronique
Published: October 2010

An iterative algorithm is developed for the computation of aeroacoustic integrals in the time domain. It is specially designed for the generation of acoustic images, thus giving access to the wavefront pattern radiated by an unsteady flow when large size source fields are considered. It is based on an iterative selection of source-observer pairs involved in the radiation process at a given time-step. It is written as an advanced-time approach, allowing easy connection with flow simulation tools. Its efficiency is related to the fraction of an observer grid step that a sound-wave covers during one time step. Test computations were performed, showing the CPU-time to be 30 to 50 times smaller than with a classical non-iterative procedure. The algorithm is applied to compute the sound radiated by a spatially evolving mixing-layer flow: it is used to compute and visualize contributions to the acoustic field from the different terms obtained by a decomposition of the Lighthill source term.
Characteristics of listener sensitivity to talker-specific phonetic detail
Authors: Theodore Rachel M. , Miller Joanne L.
Published: October 2010

Previous research shows that listeners are sensitive to talker differences in phonetic properties of speech, including voice-onset-time (VOT) in word-initial voiceless stop consonants, and that learning how a talker produces one voiceless stop transfers to another word with the same voiceless stop [Allen, J. S., and Miller, J. L. (2004). J. Acoust. Soc. Am. 115, 3171–3183]. The present experiments examined whether transfer extends to words that begin with different voiceless stops. During training, listeners heard two talkers produce a given voiceless-initial word (e.g., pain). VOTs were manipulated such that one talker produced the voiceless stop with relatively short VOTs and the other with relatively long VOTs. At test, listeners heard a short- and long-VOT variant of the same word (e.g., pain) or a word beginning with a different voiceless stop (e.g., cane or coal), and were asked to select which of the two VOT variants was most representative of a given talker. In all conditions, which variant was selected at test was in line with listeners’ exposure during training, and the effect was equally strong for the novel word and the training word. These findings suggest that accommodating talker-specific phonetic detail does not require exposure to each individual phonetic segment.
Investigation of higher spanwise Helmholtz resonance modes in slender covered cavities
Authors: de Jong A. T. , Bijl H.
Published: October 2010

Cavity aeroacoustic noise is relevant for aerospace and automotive industries and widely investigated since the 1950s. Most investigations so far consider cavities where opening length and width are of similar scale. The present investigation focuses on a less investigated setup, namely cavities that resemble the door gaps of automobiles. These cavities are both slender (width much greater than length or depth) and partially covered. Furthermore they are under influence of a low Mach number flow with a relatively thick boundary layer. Under certain conditions, these gaps can produce tonal noise. The present investigation attempts to reveal the aeroacoustic mechanism of this tonal noise for higher resonance modes. Experiments have been conducted on a simplified geometry, where unsteady internal pressures have been measured at different spanwise locations. With increasing velocity, several resonance modes occur. In order to obtain higher mode shapes, the cavity acoustic response is simulated and compared with experiment. Using the frequency-filtered simulation pressure field, the higher modes shapes are retrieved. The mode shapes can be interpreted as the slender cavity self-organizing into separate Helmholtz resonators that interact with each other. Based on this, an analytical model is derived that shows good agreement with the simulations and experimental results.
Attenuation of direct sound and the contributions of early reflections within symphony orchestras
Authors: Dammerud J. J. , Barron M.
Published: October 2010

On concert hall stages the sound traveling between players consists of the direct sound, a floor reflection and early reflections off players and objects on stage such as instruments and music stands. In smaller music ensembles, the acoustic communication between players is normally good. In larger ensembles, there is a similar situation for short distances between players. However for ensembles like a symphony orchestra, the number of players on stage results in large distances between some players with many other players sitting in between, which block the direct sound and floor reflection paths. This study investigates the sound levels on stage with and without a large orchestra present, in the absence of any stage enclosure. Sound levels within the octave bands 63–2000 Hz on an empty stage were studied analytically, while sound levels over the same frequency range with players present were investigated in a 1:25 scale model, both without and with risers on stage. The main results are presented in terms of the attenuation introduced by the orchestra, with linear models developed to describe behavior for the octave bands 500–2000 Hz.
Phonemic restoration in sensorineural hearing loss does not depend on baseline speech perception scores
Authors: Başkent Deniz
Published: October 2010

The brain can restore missing speech segments using linguistic knowledge and context. The phonemic restoration effect is commonly quantified by the increase in intelligibility of interrupted speech when the silent gaps are filled with noise bursts. In normal hearing, the restoration effect is negatively correlated with the baseline scores with interrupted speech; listeners with poorer baseline show more benefit from restoration. Reanalyzing data from Başkent et al. [(2010). Hear. Res. 260, 54–62], correlations with mild and moderate hearing impairment were observed to differ than with normal hearing. This analysis further shows that hearing impairment may affect top-down restoration of speech.
Spectral and temporal changes to speech produced in the presence of energetic and informational maskers
Authors: Cooke Martin , Lu Youyi
Published: October 2010

Talkers change the way they speak in noisy conditions. For energetic maskers, speech production changes are relatively well-understood, but less is known about how informational maskers such as competing speech affect speech production. The current study examines the effect of energetic and informational maskers on speech production by talkers speaking alone or in pairs. Talkers produced speech in quiet and in backgrounds of speech-shaped noise, speech-modulated noise, and competing speech. Relative to quiet, speech output level and fundamental frequency increased and spectral tilt flattened in proportion to the energetic masking capacity of the background. In response to modulated backgrounds, talkers were able to reduce substantially the degree of temporal overlap with the noise, with greater reduction for the competing speech background. Reduction in foreground-background overlap can be expected to lead to a release from both energetic and informational masking for listeners. Passive changes in speech rate, mean pause length or pause distribution cannot explain the overlap reduction, which appears instead to result from a purposeful process of listening while speaking. Talkers appear to monitor the background and exploit upcoming pauses, a strategy which is particularly effective for backgrounds containing intelligible speech.
A piezoelectric bone-conduction bending hearing actuator
Authors: Adamson R. B. A. , Bance M. , Brown J. A.
Published: October 2010

A prototype of a novel bone-conduction hearing actuator based on a piezoelectric bending actuator is presented. The device lies flat against the skull which would allow it to form the basis of a subcutaneous bone-anchored hearing aid. The actuator excites bending in bone through a local bending moment rather than the application of a point force as with conventional bone-anchored hearing aids. Through measurements of the cochlear velocity created by the actuator in embalmed human heads, the device is shown to exhibit high efficiency, making it a possible alternative to present-day electromagnetic bone-vibration actuators.
Stimulus factors influencing spatial release from speech-on-speech masking
Authors: Kidd Gerald , Mason Christine R. , Best Virginia , Marrone Nicole
Published: October 2010

This study examined spatial release from masking (SRM) when a target talker was masked by competing talkers or by other types of sounds. The focus was on the role of interaural time differences (ITDs) and time-varying interaural level differences (ILDs) under conditions varying in the strength of informational masking (IM). In the first experiment, a target talker was masked by two other talkers that were either colocated with the target or were symmetrically spatially separated from the target with the stimuli presented through loudspeakers. The sounds were filtered into different frequency regions to restrict the available interaural cues. The largest SRM occurred for the broadband condition followed by a low-pass condition. However, even the highest frequency bandpass-filtered condition (3–6 kHz) yielded a significant SRM. In the second experiment the stimuli were presented via earphones. The listeners identified the speech of a target talker masked by one or two other talkers or noises when the maskers were colocated with the target or were perceptually separated by ITDs. The results revealed a complex pattern of masking in which the factors affecting performance in colocated and spatially separated conditions are to a large degree independent.
Acoustic metafluids made from three acoustic fluids
Authors: Norris Andrew N. , Nagy Adam J.
Published: October 2010

Significant reduction in target strength and radiation signature can be achieved by surrounding an object with multiple concentric layers comprised of three acoustic fluids. The idea is to make a finely layered shell with the thickness of each layer defined by a unique transformation rule. The shell has the effect of steering incident acoustic energy around the structure, and conversely, reducing the radiation strength. The overall effectiveness and the precise form of the layering depends upon the densities and compressibilities of the three fluids. Nearly optimal results are obtained if one fluid has density equal to the background fluid, while the other two densities are much greater and much less than the background values. Optimal choices for the compressibilities are also found. Simulations in 2D and 3D illustrate effectiveness of the three fluid shell. The limited range of acoustic metafluids that are possible using only two fluid constituents is also discussed.
Locus equations are an acoustic expression of articulator synergy
Authors: Iskarous Khalil , Fowler Carol A. , Whalen D. H.
Published: October 2010

The study investigated the articulatory basis of locus equations, regression lines relating F2 at the start of a Consonant-Vowel (CV) transition to F2 at the middle of the vowel, with C fixed and V varying. Several studies have shown that consonants of different places of articulation have locus equation slopes that descend from labial to velar to alveolar, and intercept magnitudes that increase in the opposite order. Using formulas from the theory of bivariate regression that express regression slopes and intercepts in terms of standard deviations and averages of the variables, it is shown that the slope directly encodes a well-established measure of coarticulation resistance. It is also shown that intercepts are directly related to the degree to which the tongue body assists the formation of the constriction for the consonant. Moreover, it is shown that the linearity of locus equations and the linear relation between locus equation slopes and intercepts originates in linearity in articulation between the horizontal position of the tongue dorsum in the consonant and to that in the vowel. It is concluded that slopes and intercepts of acoustic locus equations are measures of articulator synergy.
Discriminating features of echolocation clicks of melon-headed whales (Peponocephala electra), bottlenose dolphins (Tursiops truncatus), and Gray’s spinner dolphins (Stenella longirostris longirostris)
Authors: Baumann-Pickering Simone , Wiggins Sean M. , Hildebrand John A. , Roch Marie A. , Schnitzler Hans-Ulrich
Published: October 2010

Spectral parameters were used to discriminate between echolocation clicks produced by three dolphin species at Palmyra Atoll: melon-headed whales (Peponocephala electra), bottlenose dolphins (Tursiops truncatus) and Gray’s spinner dolphins (Stenella longirostris longirostris). Single species acoustic behavior during daytime observations was recorded with a towed hydrophone array sampling at 192 and 480 kHz. Additionally, an autonomous, bottom moored High-frequency Acoustic Recording Package (HARP) collected acoustic data with a sampling rate of 200 kHz. Melon-headed whale echolocation clicks had the lowest peak and center frequencies, spinner dolphins had the highest frequencies and bottlenose dolphins were nested in between these two species. Frequency differences were significant. Temporal parameters were not well suited for classification. Feature differences were enhanced by reducing variability within a set of single clicks by calculating mean spectra for groups of clicks. Median peak frequencies of averaged clicks (group size 50) of melon-headed whales ranged between 24.4 and 29.7 kHz, of bottlenose dolphins between 26.7 and 36.7 kHz, and of spinner dolphins between 33.8 and 36.0 kHz. Discriminant function analysis showed the ability to correctly discriminate between 93% of melon-headed whales, 75% of spinner dolphins and 54% of bottlenose dolphins.
Perceived continuity and pitch shifts for complex tones with unresolved harmonics
Authors: Plack Christopher J. , Watkinson Rebecca K.
Published: October 2010

Brief complex tone bursts with fundamental frequencies (F0s) of 100, 125, 166.7, and 250 Hz were bandpass filtered between the 22nd and 30th harmonics, to produce waveforms with five regularly occurring envelope peaks (“pitch pulses”) that evoked pitches associated with their repetition period. Two such tone bursts were presented sequentially and separated by a silent interval of two periods (2/F0). When the relative phases of the two bursts were varied, such that the interpulse interval (IPI) between the last pulse of the first burst and the first pulse of the second burst was varied, the pitch of the whole sequence was little affected. This is consistent with previous results suggesting that the pitch integration window may be “reset” by a discontinuity. However, when the interval between the two bursts was filled with a noise with the same spectral envelope as the complex, variations in IPI had substantial effects on the pitch of the sequence. It is suggested that the presence of the noise causes the two tones bursts to appear continuous, hence, resetting does not occur, and the pitch mechanism is sensitive to the phase discontinuity across the silent interval.
Minimally radiating sources for personal audio
Authors: Elliott Stephen J. , Cheer Jordan , Murfet Harry , Holland Keith R.
Published: October 2010

In order to reduce annoyance from the audio output of personal devices, it is necessary to maintain the sound level at the user position while minimizing the levels elsewhere. If the dark zone, within which the sound is to be minimized, extends over the whole far field of the source, the problem reduces to that of minimizing the radiated sound power while maintaining the pressure level at the user position. It is shown analytically that the optimum two-source array then has a hypercardioid directivity and gives about 7 dB reduction in radiated sound power, compared with a monopole producing the same on-axis pressure. The performance of other linear arrays is studied using monopole simulations for the motivating example of a mobile phone. The trade-off is investigated between the performance in reducing radiated noise, and the electrical power required to drive the array for different numbers of elements. It is shown for both simulations and experiments conducted on a small array of loudspeakers under anechoic conditions, that both two and three element arrays provide a reasonable compromise between these competing requirements. The implementation of the two-source array in a coupled enclosure is also shown to reduce the electrical power requirements.
Auditory spectral integration in the perception of diphthongal vowels
Authors: Fox Robert Allen , Jacewicz Ewa , Chang Chiung-Yun
Published: October 2010

This study considers an operation of an auditory spectral integration process which may be involved in perceiving dynamic time-varying changes in speech found in diphthongs and glide-type transitions. Does the auditory system need explicit vowel formants to track the dynamic changes over time? Listeners classified diphthongs on the basis of a moving center of gravity (COG) brought about by changing intensity ratio of static spectral components instead of changing an F2. Listeners were unable to detect COG movement only when the F2 change was small (160 Hz) or when the separation between the static components was large (4.95 bark).
Fishbone-like instability in a looped-tube thermoacoustic engine
Authors: Yu Zhibin , Jaworski Artur J. , Abduljalil Abdulrahman S.
Published: October 2010

Quasi-periodic bursts of acoustic oscillations were observed during the start-up process in a looped-tube thermoacoustic engine. The acoustic oscillations have a constant frequency of 111 Hz, while the bursts have “quasi-periods” in the order of 14–25 s. The quasi-periodic bursts show a new mode of amplitude growth in this thermoacoustic engine. The envelope of the acoustic oscillations has a fishbone-like shape. The nature of the observed fishbone-like instabilities suggests a strong interaction between the acoustic and temperature field.
Architectural acoustic design of auditorium in a sport club in San Pedro Garza Garcia, Mexico.
Authors: Lozano-Villarreal Eduardo L.
Published: October 2010

In this paper the architectonic acoustic redesign of the Auditorium of the San Agustin Sport Club located in San Pedro Garza Garcia, Mexico, is presented, which was constructed 20 years ago and that required a small expansion, a modernization of their facilities and an improvement of their acoustic characteristics. The objectives of the design and the actions conducted to obtain them are described.
Tests of sound absorption of seats of the Colon Theatre in Buenos Aires.
Authors: Vechiatti Nilda , Iasi Federico , Velis Ariel , Armas Alejandro , Tomeo Daniel , Bontti Horacio
Published: October 2010

Having passed 100 years after its inauguration, the Colon Theatre located in Buenos Aires City is one of the most outstanding opera and symphonic music theatre of the world, and being one of the main architectural monuments of the Argentine Republic, it has needed a conservative restoration and a technological update. This has given place to the realization of a series of projects that guarantee its value with the premise to keep its acoustic quality. The methodology employed to select the textile material replacement and objects that have influence in the acoustics of the room consist in subjecting to laboratory tests the original samples together with their replacements in order to objectively characterize them and to verify that they had similar properties of sound absorption. This work presents the laboratory procedure which allowed the selection of textile material of seats replacement from reverberant chamber and Kundt tube tests.
History of proposed Acoustical Society standard on “Underwater Passive Acoustic Monitoring for Bioacoustic Applications”.
Authors: Thode Aaron , Mellinger David K.
Published: October 2010

In 2005 an ASA working group was formed to examine whether a standard should exist for “Passive Acoustic Monitoring for Marine Mammal Mitigation for Seismic Surveys”. Public discussions at subsequent meetings quickly showed that no consensus existed for specifying hardware requirements for passive acoustic measurements, but consensus did seem possible for specifying “minimum requirements for recording and reporting bioacoustic data”. The proposed standard was renamed “Underwater Passive Acoustic Monitoring for Bioacoustic Applications” with three defined goals: (1) providing a set of requirements for information to be documented while recording acoustic data at sea (metadata requirements); (2) detailing the minimum information about acoustic hardware and software to be included when reporting results in gray or peer-reviewed literature; and (3) specifying metrics to be used when summarizing the features of an acoustic signal, such as signal-to-noise ratio. A set of recommended best-practice procedures and equipment capabilities would also be included as an informative annex. After languishing for several years, an attempt is being made to develop the standard further. This presentation describes the ASA standard, outlines the development process, and sketches the current thinking on the standard, with an emphasis on the metrics portion.
The effects of multiple scattering on bubble cloud and fish school cross sections.
Authors: Hahn Thomas R. , Chen Xiaojun
Published: October 2010

Scattering or transmission of sound from or through clouds of bubbles or schools of swim bladder bearing fish is a problem of considerable practical importance in acoustical oceanography that has received ongoing interest from the community for many years. Part of this interest is rooted in the fact that mutual acoustic interactions of the scatterers in the form of multiple scattering complicate the physics of the problem. In practice, this can be both a limitation, or, if physically well understood, an opportunity that can lead to more powerful inversion schemes. In this paper, several multiple scattering effects, such as collective resonance modes and frequency shifts are explored using an effective medium approach as well as direct forward numerical computations. While conceptually of great utility, analytically treated effective medium techniques are mostly limited to simple geometries. On the other hand, direct numerical computations from first principles can accommodate complex, realistic configurations of a large number of scatterers. [Work supported by the Office of Naval Research.]
Experimental evidence of bubble cloud resonances of fish schools.
Authors: Diachok Orest
Published: October 2010

Dispersed sardines generally form schools at dawn. During this period the average separation between sardines, S, changes from about 10 fish lengths, L, to about L. S in sardine schools is much smaller than the wavelength at the resonance frequency of individuals, f, which suggests that sardine schools may resonate at “bubble cloud” frequencies. Concurrent bio-alpha, echo sounder, and biological sampling measurements in the Gulf of Lion revealed that absorption lines due to dispersed sardines systematically changed from 1.3 to 2.7 kHz as the sardines descended from 20 m at night to 65 m at sunrise. As schools formed, f abruptly shifted to 1.7 kHz. Temporal changes of f during dawn were consistent with theoretical computations, based on previously reported swim bladder radius, and concurrent depth measurements. The measured resonance frequency of schools during daytime was 0.6 times the value of f of dispersed sardines at 65 m. The observed frequency shift is consistent with a hybrid model of the fundamental resonance frequency of a bubble cloud, which is based on theories developed by Feuillade et al. (1996) and d’Agostino and Brennan (1988), and S = 0.8 L and N = 5000 fish per school. [Work supported by ONR.]
Robust Capon beamforming for passive cavitation mapping during high-intensity focused ultrasound therapy.
Authors: Coviello Christian M. , Faragher Stuart R. , Coussios Constantin-C.
Published: October 2010

A passive method that uses time exposure acoustics (TEA) to map inertial cavitation activity in real time during therapeutic ultrasound exposure was recently presented [Gyongy and Coussios, IEEE Trans. Biomed. Eng. 57, 48–56 (2010)]. While this approach provides sub-millimetric spatial resolution transversely to the high-intensity focused ultrasound (HIFU) beam, its axial resolution requires improvement. Furthermore, the TEA method is expected to have a lower overall resolution and diminished ability to reject interference and noise compared to an adaptive beamforming approach. To address these limitations, we propose the use of the adaptive, robust Capon beamformer (RCB), which has been previously shown in the context of active, 2-D ultrasound imaging to provide high resolution, good interference suppression, and robustness against steering vector errors. Using a multi-element tomographic cavitation sensor being developed for quality assessment of clinical HIFU transducers, the effectiveness of RCB is demonstrated for improved 3-D passive localization of inertial cavitation compared to TEA using simulated and experimental data.
Analysis of the variations in frequency for a trumpet B-flat to use “mute”.
Authors: Macías Claudia , Rabadán Itzalá , Servín Ilhuicamina
Published: October 2010

The effect that is produced in the acoustical characteristics of a B-flat trumpet when an obstacle is located at the exit of the bell has been investigated. To know how these characteristics have been modified, a professional trumpet player played some tones with three different conditions in the bell: bell free of obstacles, bell with a Harmon mute, and bell with the musician’s hand. The measurements were made in an anechoic chamber. Data were registered through a sound level meter type II which was connected to a computer and data were saved in a computer program, then the results were analyzed. The sound radiation patterns reveal that the energy that is radiated by the trumpet diminishes in all directions. The spectra show that the amplitude as well as the frequency of the signals change for all the tones. That is to say, when there is an obstacle at the exit of the bell, the boundary condition is different, and with this, the impedance and the effective length of the trumpet are affected. As a result, the frequency of the modes of vibration, the standing wave pattern as well as the timbre are affected.
Optimal valve slide lengths for double and triple horns.
Authors: Young Frederick
Published: October 2010

The optimal valve slide lengths for three valve double and triple brass instruments are investigated to ensure that the errors in intonation never exceed five cents sharp or flat over the range of playing. Using the method of least squares to minimize the intonation errors caused by various common valve combinations, it is shown that tuning the open tone 3.2 cents sharp and making suitable valve slide adjustments yield an overall root mean square error of about 2.6 cents. This calculation does not count the errors resulting with the 13 and 123 valve combinations encountered in the low register of the F side of the horn. At the risk of stuffiness, these notes are often corrected by alteration of the right hand position. The best overall intonation is shown to exist for the triple horn in F, Bb, and high Eb, exhibiting the overall root mean square error of about 2.6 cents. In this case the pedal notes on the high Eb side of the horn are used. They are fingered 12 and 23 for said low G and F#. The more common triple horn in F, Bb, and high F requires the use of the 13 and 123 combinations.
The influence of reed curvature on the tone quality of lingual organ pipes.
Authors: Plitnik George , Angster Judit
Published: October 2010

Given certain design constraints, such as the type of stop being voiced and the desired tone quality, reed voicers must use consummate skill to curve each tongue so as to produce the best and most stable tone, as well as maintain a consistent tone quality across an entire rank of pipes. The curvature given to a reed tongue influences not only the harmonic structure of the steady-state sound, but also the attack. Two fundamentally different types of curvature are typically employed, the chorus reed (trompette) curve (which yields a bright sound) and the smooth-toned curve employed for solo reeds such as the clarinet. This study investigated the effect of reed curvature on the vibration and tone of reed tongues of both types. Two F2 pipes (a trompette and a clarinet) were constructed and voiced with six different tongues each to produce a variety of tones. The reed’s vibration was measured under typical conditions by laser vibrometer; the pressure waves in the boot and in the shallot were measured by means of 1/8-in. microphones and the emitted sound was recorded at the egress. By performing various measurements simultaneously, phase differences were also determined.
Sound intensity measurement to 195-MW gas turbine.
Authors: Montano Walter , Gushiquen Elena
Published: October 2010

This work presents an experience of sound intensity measurement to 195-MW gas turbine installed in Peru.
Sound absorption of single- and double-layer microperforated insertion units.
Authors: Ruiz Heidi , Cobo Pedro
Published: October 2010

Sound absorption by microperforated panels (MPPs) has received increasing attention recently as an alternative in applications with special cleanliness and health requirements. Since the hole diameter-to-panel thickness ratio must be close to unity, MPPs result limp, and therefore difficult to handle for practical applications. Microperforated insertion units (MIUs) were proposed recently to solve this trouble. They combine a millimetric panel with a micrometric mesh to provide an absorption curve similar to that of an MPP. The disadvantage of an MIU, as compared with an MPP, is that its performance depends on the tuning of seven parameters. Furthermore, when a double-layer absorber is required to increase the absorption frequency band, the number of constitutive parameters to be tuned becomes the design rather arduous. Therefore, it could be attractive to know the combination of constitutive parameters, within given variation ranges, which provides the maximum mean absorption for a prescribed frequency band. This is a typical optimization problem. Thus, this paper proposes the application of simulated annealing for optimizing the mean absorption of single- and double-layer MIUs within given variation ranges of their constitutive parameters.
Plasma synthetic jet actuators as a means of improving the performance of turbofan acoustic liners.
Authors: Barnobi Christopher L. , Fuller Chris R.
Published: October 2010

A turbofan engine acoustic liner is effective at reducing propagated noise. However, there is room for improving performance or making the liner more compact. Plasma actuators have been shown to be useful flow control devices in a number of fluid flow situations. Combining the plasma actuator (PSJA) and passive liner technologies offers the promise that the attenuation of the acoustic liner can be improved with the addition of the active actuators. The research was divided into two realms: oscillatory flow and bias flow induced by the plasma actuator. A waveguide was constructed with a disturbance speaker at one end, an anechoic termination at the other end, and a mounting for Helmholtz resonators (HRs) in the middle. The PSJA technology was integrated into the neck of the a single HR. A single frequency, feed forward test was conducted to evaluate the oscillatory flow. This test showed that the implementation of the PSJA with a feed forward system could produce an additional 3 dB of attenuation. For this test arrangement the bias flow did not show any additional measurable attenuation. Interpretation of the results are discussed.
Coarticulation of non-modal phonation.
Authors: Garellek Marc
Published: October 2010

Although there are many studies on the acoustics of phonation, few deal specifically with the coarticulation of non-modal phonations. Using data from three languages (English, White Hmong, and Korean), this project describes the acoustics of breathy-to-creaky phonation contours in vowels. In English, such contours are found in vowels preceded by [h] or an aspirated stop, and followed by a preglottalized coda-stop, e.g., “cat.” In Hmong, the contours are found in vowels with a phonemic creaky tone that are preceded by an aspirated stop or [h]. In Korean, the contours are derived from vowels preceded by an aspirated or lenis stop and followed by a coda-stop, which is found to show preglottalization. Twelve speakers of each language were recorded saying monosyllables with expected phonation contours in carrier sentences. The phonation was analyzed using VOICESAUCE [Shue et al. (2009)], which outputs a value at each millisecond for several acoustic measures. Time courses for measures like H1*-H2* and harmonics-to-noise ratio show support for the presence of breathy-creaky contours in the three languages. I analyze the cross-linguistic differences in the timing of the contours in light of previous findings on the timing of non-modal phonation [e.g., Blankenship (2002)] and current theories of coarticulation.
Relations among subglottal resonances, vowel formants, and speaker height, gender, and native language.
Authors: Arsikere Harish , Lee Yi-Hui , Lulich Steven M. , Morton John R. , Sommers Mitchell S. , Alwan Abeer
Published: October 2010

Subglottal resonances (SGRs) have recently been used in automatic speaker normalization (SN), leading to improvements in children’s speech recognition [Wang et al. (2009)]. It is hypothesized that human listeners use SGRs for SN as well. However, the suitability of SGRs for SN has not been adequately investigated. SGRs and formants from adult speakers of American English and Mexican Spanish were measured using a new speech corpus with simultaneous (subglottal) accelerometer recordings [Lulich et al. (2010)]. The corpus has been analyzed at a broad level to understand relations among SGRs, speaker height, native language and gender, and formant frequencies as well as the variation of SGRs across vowels and speakers. It is shown that SGRs are roughly constant for a given speaker, regardless of their native spoken language, but differ from speaker to speaker. SGRs are therefore well suited for use in SN and perhaps in speaker identification. Preliminary analyzes also show that SGRs are correlated with each other and can be used to develop/validate simple models of subglottal acoustics, robust algorithms for SGR estimation, and models of human SN. SGRs are also correlated with height, and there are gender-specific differences in SGR frequencies. [Work supported in part by the NSF.]
Temporal analysis of articulatory speech errors using direct image analysis of real time magnetic resonance imaging.
Authors: Proctor Michael , Lammert Adam , Goldstein Louis , Narayanan Shrikanth
Published: October 2010

Articulometry studies have demonstrated that speech errors often involve gestural intrusions that are coproduced with other gestures and can go unnoticed because they are not always perceived to be segmental errors. [Mowrey and MacKay (1990)]. Real time magnetic resonance imaging was used to examine tongue movement during the production of English minimal pairs “cop-top,” “kid-kim,” “sop-shop,” and “bad-bang.” Subjects’ upper airways were imaged in the midsagittal plane while they uttered repetitions of each word pair as rapidly as possible for 15 sec. Degree of constriction in each region of interest (labial, alveolar, post-alveolar, and velic) was automatically tracked with direct image processing techniques. We calculate the mean intensity of temporally correlated pixels in that region–a metric which has been found to provide a robust estimate of constriction degree in noisy data. [Lammert (in preparation).] Gestural intrusions are observed throughout these data; frequency of occurrence increases with speech rate. Intrusions are invariably synchronous with the alternating contrastive gesture, e.g., additional velic gestures are observed at the same time as the tongue tip constriction in the word pair “cop-top.” These data are consistent with the hypothesis that speech production involves the coordination of dynamically defined action units. [Goldstein et al. (2007).]
Frequency bark cepstral coefficients extraction for speech analysis by synthesis.
Authors: Herrera Abel , Del rio Fernando
Published: October 2010

The Mel scale was proposed in 1937, following a series of experiments used to establish a perceptual scale. The use of the Mel scale is almost standard for speech recognition application. The Bark scale divides the audible spectrum into 24 critical bands that try to mimic the frequency response of the human ear. This article describes the process used to extract a set of cepstral coefficients from a warped frequency space (Mel and Bark) and analyze the perceived differences in the reconstructed signal. We will try to determine if there is any audible improvement between these two most warping functions for the purpose of speech analysis by synthesis. We will use the same procedure for parameter extraction and signal reconstruction for both functions, replacing only the warping scale used, to minimize the distortion other elements might add to the results. After running the waveform through both processes and reconstructing a wave signal from the parameters, while the resulting output was somewhat different, there were slight differences between the bark and mel generated signals. Statistical tests are now running between Mel and Bark scales.
Boundary and elastic effects on backscattering by aluminum cylinders: Experiments and modeling for tilted cylinders viewed at grazing incidence.
Authors: La Follett Jon R. , Marston Philip L.
Published: October 2010

Close proximity to a boundary or partial exposure to the incident sound modifies the frequency response of elastic objects. Understanding these changes in high-frequency scattering is important for detection and classification of metallic objects located near a boundary. Laboratory experiments, ray theory, synthetic aperture sonar (SAS) imaging, and backscattering spectroscopy were used to explore the effect of partial exposure and close proximity to a planar boundary for a solid aluminum cylinder. To investigate these boundary effects, targets were suspended through the air-water interface of a water tank and insonified from below at grazing incidence. Backscattering measurements were made as the target was lowered through the air-water interface, increasing the portion of the target exposed to sound. Backscattering measurements were also made as a function of aspect angle for varying levels of exposure. Line scan measurements were also obtained to construct SAS images. Some of the structure in the frequency response could be explained using a previously developed ray-based theory [K. Gipson and P. L. Marston, J. Acoust. Soc. Am. 106, 1673–1680 (1999); J. Acoust. Soc. Am. 107, 112–117 (2000)] involving leaky Rayleigh waves. The coupling to rays crossing the flat end of the cylinder strongly depends on the amount of exposure. [Work supported by ONR.]
Modeling the effects of sediments on the acoustic response of buried elastic cylinders to low-frequency broadband signals.
Authors: Sanders William M. , Calvo David , Bibee L. Dale
Published: October 2010

Low-frequency broadband (LFBB) sonars have the advantage of penetration into the sea-floor, thus allowing ensonification of buried targets, but the disadvantage of inferior spatial resolution. Hence, this technology heavily relies on reducing false alarms through recognition of details of the acoustic signature. This reports on an effort to characterize the changes in the acoustic signatures that occur for elastic cylinders buried in various sediments. Numerical modeling of both target and reverberation highlight several difficulties in detection and classification of buried targets, most notably reduced signal excess for targets in sands and larger grain size sediments. Moreover, practical limits on sources and receivers limit the usable bandwidth of LFBB systems, consequently restricting the observable information used for characterizing the acoustic response of targets. Time-frequency analysis methods of modeled signals reveal little information that distinguishes a signal of interest from a rigid or point scatterer (potential false targets).
Distribution and spatial characteristics of zooplankton and nekton aggregations in Cape Cod Bay during the spring of 2010.
Authors: Warren Joseph D. , Parks Susan E. , Miksis-Olds Jennifer L.
Published: October 2010

Acoustic backscatter measurements were made throughout Cape Cod Bay during March and April of 2010. This area is a highly productive environment, particularly following the spring bloom, and large aggregations of small zooplankton (i.e., copepods) support a variety of higher trophic level animals ranging from small fish to large mysticetes. Multiple acoustic echosounders (38, 120, 200, and 710 kHz) and a 600-kHz acoustic Doppler current profiler were deployed from a towed platform in Cape Cod Bay and measured volume backscattering strength for the water column which varied in depth throughout the bay. Video and net sampling systems were used to verify the identity of scattering targets which consisted of both zooplankton and small fish, and multiple CTD casts were conducted to characterize the hydrography of the area. Copepods were abundant in the very near-surface (less than 10 m) while fish aggregations occurred throughout the water column. Spatial characteristics of towed data were compared to those collected by a bottom-mounted, upward-looking three frequency (125, 200, and 460 kHz) echosounder that was also deployed in Cape Cod Bay during this time period.
Theory of wave propagation in marine sediments.
Authors: Buckingham Michael J.
Published: October 2010

Saturated, unconsolidated marine sediments support sound waves and shear waves, each of which is dispersive in that its phase speed varies with frequency and the corresponding attenuation scales as the first power of frequency over an extended frequency range. A theory of sound wave and shear wave propagation in unconsolidated marine sediments has recently been developed in which the dissipation is based on a particular form of intergranular interaction involving the molecularly thin layer of pore fluid at grain contacts. As grain-to-grain sliding progresses, the contact is postulated to become progressively stiffer, a phenomenon known as strain-hardening, adapted from the literature on creep in metals and metal alloys. The theory returns algebraic expressions for the phase speed and attenuation of both types of wave, and these expressions depend on frequency as well as the geoacoustic parameters of the sediment. A comparison of the theoretical dispersion relations with data obtained during the ONR-supported SAX99 experiment shows good agreement over the frequency range range from 2–400 kHz. The theoretical expressions also fit measurements, at a fixed frequency, of phase speeds and attenuations versus porosity, overburden pressure, and mean grain diameter. [Research supported by ONR.]
Forensic voice comparison and forensic acoustics.
Authors: Morrison Geoffrey Stewart , Ramos Daniel
Published: October 2010

In February 2009, the National Research Council Report to Congress on Strengthening Forensic Science in the United States found that “some forensic disciplines are supported by little rigorous systematic research to validate the discipline’s basic premises and techniques. There is no evident reason why such research cannot be conducted” (p. 22), and that “The development of scientific research, training, technology, and databases associated with DNA analysis have resulted from substantial and steady federal support… Similar support must be given to all credible forensic science disciplines if they are to achieve the degrees of reliability needed to serve the goals of justice” (p. 13). Over the last decade, a small number of researchers have been working on developing demonstrably valid and reliable forensic voice comparison with evidence evaluated using the same framework as is applied to the forensic evaluation of DNA. This tutorial will present an introduction to the forensic evaluation of acoustic evidence using this framework. Both acoustic-phonetic and signal-processing approaches to forensic voice comparison will be described. The focus will be on evidence in the form of voice recordings, but the framework can also be applied to other forms of evidence, including audio recordings of other types of acoustic events, and the tutorial should therefore be of value to anyone interested in forensic acoustics in general.
The influence of background noise in student achievement.
Authors: Jaramillo Ana M. , Ermann Michael
Published: October 2010

During our entire life span, we spend time in the activity of learning (anything from basic survival skills to highly intellectual processes), but this activity occupies most of the time during the first years of our lives. The classroom becomes then the official learning space that is designed to be conducive to this activity. The learning process, regardless of the task difficulty, is not a mechanical one. It requires a mental process, concentration, and attention in various degrees. Distractions can be detrimental to the learning. Most of the learning activities that occur at school settings require some kind of oral communication (teacher-student or student-student), and these activities call for appropriate room acoustics. In the presence of high levels of background noise, human beings have other resources to better understand the signal of interest. Those can be visual cues, previous knowledge of the topic, or mental ability to “fill in the blanks” in the received speech. The last two are abilities that come with age and experience. The purpose of this study is to better assert the importance of acoustics parameters in the design of classrooms and their relation to student achievement.
Architectural acoustic design of a residence in San Pedro Garza Garcia, Mexico.
Authors: Lozano-Villarreal Eduardo L.
Published: October 2010

In Latin America it is not common that the acoustic aspects in the construction of houses and residences were considered from the design. In this paper is presented a case of design of a residence, the property of an architect, in which from the initial stages the acoustic aspects were considered specifically for formal living room and piano area, TV room, home theater, bedrooms, dining room, kitchen, and bar room.
Information technology challenges in passive acoustic monitoring of marine life.
Authors: Weise Michael , Eckman James
Published: October 2010

The explosion of passive acoustic monitoring (PAM) of marine life is generating massive amounts of data and creating information technology (IT) challenges in data collection, analysis, management, storage, and dissemination. We evaluate current levels of advancement for each IT challenge and identify areas that require further development. Current DCL software is inadequate to identify all relevant calls and we do not adequately understand the complete range of sounds of interest, which necessitates the collection of high-bandwidth and long duration data sets. Large data sets generated by state-of-the-art PAM devices present several major challenges that require development of the computational capacity for timely data processing and display. Depending on the number of detectors and classifiers to be run, solutions may require anything from parallel computing to developing community-wide access to high throughput computing centers. New database approaches are needed that will enable users to query against known human or machine-generated annotations (detections, classifications) of existing data, add new annotation sets including detailed information on how they were created, export data products to external visualization services, and interface with existing external analytical tool sets. Databases or analytical services should be kept in repositories that are publicly accessible.