bluuebunny/crossref_metadata_2025 huggingface dataset:
Perceptual interactions among components of a spectral-domain voice source model
Authors: Garellek Marc , Samlan Robin A. , Kreiman Jody , Gerratt Bruce
Published: November 2013

A psychoacoustic model of the source spectrum has been proposed in which source contributions to overall voice quality can be quantified by four spectral slope components: H1-H2 (the amplitude difference between the first and second harmonics), H2-H4, H4-2000 Hz (i.e., the harmonic nearest to 2000 Hz), and 2000–5000 Hz. The natural variability of these components has been described, along with the just noticeable differences (JNDs) for each component. The goals of this study are to identify how perceptual sensitivity to each component slope varies as a function of the adjacent slope(s). The JNDs were obtained for stimuli based on synthetic copies of one female voice. The stimuli were manipulated so that spectral slope varied in 0.5 dB increments (1 dB for 2000–5000 Hz) for a particular component at “high” and “low” values of the adjacent slopes. Thirty-three listeners completed an adaptive up-down paradigm. Preliminary results suggest that sensitivity to a particular spectral component varies as a function of some adjacent components more than the other. Furthermore, sensitivity varies based on whether the adjacent component has a high or low slope. These interactions among spectral components will be interpreted with respect to the variability in spectral configuration observed in 144 voices.
Lexical segmentation of speech from energy above 5 kHz
Authors: Vitela A. Davi , Monson Brian B. , Lotto Andrew J.
Published: November 2013

Research in the field of speech perception has traditionally focused on the acoustic information or cues present in the frequency region below 5 kHz, thus ignoring high frequency energy (HFE). A recent series of studies, however, demonstrated that listeners could determine the mode of production (speech or singing) and further, could identify what was being spoken or sung from the HFE alone and with a speech-shaped masking noise in the lower frequencies. This begs the question as to what types of information listeners are extracting to guide their perception. The current study examined the ability of listeners to transcribe short semantically-unpredictable but syntactically-well-formed spoken phrases that were high-pass filtered at 5.6 kHz. Of particular interest was the ability of some listeners to correctly determine the placement of word boundaries even without the availability of low-frequency information. These findings add to a growing literature on the linguistically relevant information present in higher frequency regions. Results will be framed within current theories of acoustic signatures to lexical segmentation. [Work supported by NIH-NIDCD.]
Prosodic disambiguation of Korean relative clause attachments
Authors: Chung Younah , Kim Chongdok
Published: November 2013

Korean relative clauses do not have to be adjacent to the substantives they modify; genitive noun phrases can interpose between the relative clause and the substantive. Thus, the syntactic analysis of a given relative clause is inherently ambiguous, such that the relative clause can modify either the head noun of a genitive noun phrase or the complex noun phrase as a whole. However, in spoken language, one rarely finds this type of ambiguity even though the relative clause could modify either of the two nouns. This suggests that speakers use prosody to convey intended meaning, with different prosodic cues associated with different syntactic boundaries, thus, providing information necessary for disambiguation. We examined the clarification of surface structure ambiguity in Korean relative clause attachments via prosody. The survey confirmed that native speakers think relative clauses are surface ambiguous. The acoustical analysis revealed that prosodic disambiguation consists of pause insertion, pitch raising, and final lengthening at the syntactic boundary. Regarding the relative importance of different prosodic measures used by speakers, we discovered that pitch raising was a more powerful measure than final lengthening in prosodic disambiguation, and that pausing played the least important role in the parsing of an ambiguous relative clause.
Use of acoustic cues in the perception of complex syllable structure
Authors: Lee Goun
Published: November 2013

This study examines second/foreign language learners’ (L2ers’) use of acoustic cues in the perception of syllable structure (onset clusters) that does not exist in the native language (L1, here, Korean). It investigates whether the target-like perception of syllable structure is facilitated by VOT ([stɪn] vs [sətɪn]) and partial devoicing of the liquid ([plim] vs [pəlim]) as compared to when either cue is absent ([blint] vs [bəlint]). This study also examined whether production errors can be predicted by perception errors. Twelve Korean-speaking English L2ers and 12 native English speakers completed AXB and production tasks in which they listened to and produced nonce words in the above three conditions. The AXB results showed significant effects of L1 and condition, but no interaction between the two. Participants were most accurate on the condition with VOT (English: 98%, Korean: 85%), followed by partial devoicing of the liquid (English: 96%, Korean: 79%) and without either cue (English: 94%, Korean: 74%). L2ers’ perception and production patterned alike, but no correlation was found between the two. These findings suggest that acoustic cues like VOT and partial devoicing of the liquid facilitate L2ers’ perception of new syllable structure, but do not play a direct role in its production.
The perception of English [h] and [ɹ] by Brazilian Portuguese speakers
Authors: Osborne Denise M.
Published: November 2013

Brazilian Portuguese (BP) learners of English have difficulties in differentiating between initial English [h] and [ɹ] (Zimmer, Silveira, and Alvers, 2009). This study investigates how speakers who have BP as their L1 and English as their L2 perceive the phonetic distance of English [h] and [ɹ], and how they and monolingual BP speakers map these phonemes onto BP sound categories. 32 native BP learners of English participated in three consecutive experiments: AXB Discrimination, Identification, and Assimilation Tests. In addition, 18 monolingual BP speakers participated in the same Assimilation test. Significant effects in ANOVAs on the three experiments support the results. Beginners and intermediates were able to hear the distinction acoustically. Only intermediates, however, used the distinction to identify English words. Both monolingual BP speakers and intermediates assimilate English [h] primary to BP double  (reflecting the dialectal and allophonic variation of the BP rhotic sounds). Beginners showed a failure to assimilate L2 sounds to their L1 BP categories. Comparison across these experiments shows that, at some stages of learning, BP speakers experience difficulty in evaluating these L2 sounds relative to their L1 inventory and in using the L2 distinction at the lexical level.
Detecting speaker change in background audio streams
Authors: Toh Hilary , Lee Pei Xuan , Lim Boon Pang , Chen Nancy F.
Published: November 2013

The cocktail party effect refers to the ability of humans to selectively focus on one speech stream among multiple human-generated background conversations and noise sources. This ability is influenced by various factors including directionality, speaking rates, different speech accents and speaking styles. It is displayed most clearly as a binaural effect, requiring listeners to be able to identify and differentiate between multiple sound sources simultaneously. Past studies [Cherry, J. Acoust. Soc. Am. 25(5), 975–979 (1953)], have shown that listeners can detect a change of speaker voice from male to female in unattended audio streams, while focusing their attention on repeating speech in an attended audio stream. Our work further investigates this by focusing on speaker change across the same gender: a more difficult task given a smaller variance in pitch across speakers. Experiments were conducted on 24 listeners and findings suggest that they are able to recognize speaker changes of the same gender. Two factor ANOVA shows an interaction between listener and speaker gender (F(1, 22) = 7.688, p = 0.01), suggesting listeners perform better when detecting speaker changes within their own gender.
The effects of listener biases on speech intelligibility
Authors: Russell Jamie , Babel Molly
Published: November 2013

Race, gender, and age have traditionally been considered the three big social categories perceivers attend to. Recent research has highlighted how perceivers, listeners in this case, use the acoustic-phonetic information from spoken language to evaluate and categorize individuals. For example, studies have shown that different dialects elicit varying judgments of intelligence, friendliness and attractiveness. Such biases have implications regarding our assessment of individuals, be it in the clinic or the courtroom. While we know that our perception of speech can trigger biases, it is important to explore the opposite—whether our biases affect our perception of speech. This study aims to contribute to the knowledge base of the latter by examining the effects of listener biases on speech intelligibility. Listeners will be presented with sentences, independently controlled for clarity, produced by model talkers of different dialects and backgrounds. This auditory stimuli will be accompanied by an image or description of the talker as a method of eliciting or constructing a preconceived linguistic bias. After each sentence, participants will be asked to type out what they heard. Analyses will examine the proportion of correct words, confidence ratings, response time, and other measures exploring participants’ ratings of vocal qualities.
Active–passive acoustic system for underwater port protection
Authors: Salloum Hady , Meeecham Andrew , Sutin Alexander
Published: November 2013

Active and passive acoustic systems may be used for port protection against threats from divers, free swimmers, Unmanned Underwater Vehicles, etc. Currently, underwater port protection is provided by Diver Detection Sonars (DDS), and Sonardyne has developed the market-leading active system, Sentinel. Stevens’ scientific research in passive acoustics led to the development of algorithms for threat detection that were realized in the Stevens Passive Acoustic Detection System (SPADES). Sonardyne and Stevens have formed a partnership to investigate a combined active/passive system that will leverage the functionality of existing sensors to design, develop, and produce a system with superior capabilities and performance as opposed to a single system. The combined system provides detection not only for underwater targets, but also for surface vessels. Possible configurations include: (1) a scenario where acoustic pulses emitted by the Sonardyne sonar and reflected by the target can be received and processed by SPADES; (2) an “acoustic fence,” whereby the detection of targets occurs as they cross a line between the transmitter and receiver. This configuration takes advantage of the significant increase in target scattering strength in the forward direction versus that from the backscatter; and (3) a fusion between detections and/or tracks from the passive and active sensors to provide an increased probability of detection and reduced probability of false alarm.
Accuracy and resolution of bearing measurements for crossed-dipole receiver
Authors: Liu Chunsheng , Trevorrow Mark V.
Published: November 2013

A well-known system for estimating the bearing to an underwater acoustic source consists of two crossed dipole sensors and an omni-directional sensor. At DRDC Atlantic, several bearing estimation methods for this three-channel system in the presence of ocean noise have been examined with the goal of minimizing the bearing error. Example algorithms are arctangent and maximum likelihood beamformer. These algorithms have trade-offs between estimation accuracy and computational efficiency, because any practical bearing-estimation algorithm must remain efficient enough for implementation in a real-time sonar processor. The accuracy of these algorithms can be demonstrated through comparison with the Cramér-Rao lower bound. Previously the calculation of bearing accuracy was based on the assumption of isotropic noise and a single signal source. However, the case of anisotropic noise and multiple-sources is more realistic, especially for bistatic or multistatic active sonar. Adaptive methods such as the Minimum Variance Distortionless Response (MVDR) beamformer will be explored to address this problem. The paper will discuss the potential improvement of bearing estimate accuracy and bearing resolution through numerical models.
Effect of internal waves on the waveguide invariant distribution
Authors: Rouseff Daniel
Published: November 2013

Multipath propagation in the ocean waveguide results in constructive and destructive interference between the paths. The resulting interference pattern, mapped versus range and frequency, often exhibits striations, alternating bands of high and low intensity. In simple waveguides, the trajectory of these striations can often be described by a single scalar parameter, the so-called waveguide invariant. In more complicated waveguides, the concept can be generalized to create the waveguide invariant distribution. In the present work, the effects of shallow water internal waves on the waveguide invariant distribution are examined. It is shown how internal waves can blur otherwise sharp striations and flatten the waveguide invariant distribution. [Work supported by ONR.]
From Swarm 1995 to Shallow Water Experiment 2006: What have we learned in shallow waveguide acoustics?
Authors: Badiey Mohsen
Published: November 2013

Last 20 years have witnessed some very interesting scientific discoveries in shallow water waveguide physics. While before1995 SWARM experiment most studies in shallow water waveguides considered two-dimensional (2D) slices of the ocean waveguide to describe the behavior of sound wave propagation, many studies in the recent years have focused on the three dimensionality of the acoustic wave propagation in the presence of water column variability. This paper summarizes the highlights of what has been done with reference to the published literature and some ongoing work. [Work supported by ONR322OA.]
An examination of the minimum construction necessary to improve the sound isolation in a university’s existing music building
Authors: Masoner Ashley
Published: November 2013

The National Association of Schools of Music (NASM) is the organization responsible for accrediting both degree- and non-degree granting music schools in the United States. Typically, NASM accreditation is based on the musical program itself, but what happens when an existing building's sound isolation is so poor it threatens a school's accreditation status? As is often the case in the Arts, the University of Wyoming has a limited budget to use for upgrades in their existing Music building. Through a series of mock-up tests, Acoustic Dimensions was able to identify the most critical noise-flanking paths and recommend the most cost effective means of raising the NIC values between practice rooms to levels that better accommodate simultaneous use of adjacent spaces.
The isolation of Lookingglass Theatre, or how an active municipal pumping station became the site for a successful theater
Authors: Miller Gregory A.
Published: November 2013

In search of a new permanent home, the Lookingglass Theatre Company was offered the chance to transform a former steam generation plant within the Chicago Avenue Pumping Station into a multi-venue theater. The Pumping Station is a historic structure—one of the few to survive the 1871 Chicago Fire—but remains an active part of the municipal water supply, pumping water to the near north side of the city. The pump room is less than 5 ft. from the site of the main theater, a 270-seat reconfigurable space specified to achieve a background noise level of RC-25. This paper will describe design challenges identified for achieving this level of acoustic separation, the construction challenges encountered building within a 130-year-old historically protected structure, and the successful result achieved by overcoming these challenges.
Design and implementation of an open-plan art gallery with heavily amplified audio/video works
Authors: Strong John T. , Giegold Carl P.
Published: November 2013

An exhibit consisting of short film and video works by internationally recognized artist and film director Steve McQueen was installed in a large open-plan gallery at the Art Institute of Chicago. Several of the works included a heavily amplified audio component with very high levels of low-frequency energy, such as machine noise and hip-hop music. The layout of the gallery dictated that these works be placed in close proximity to each other as well as to works requiring a very low noise floor, while maintaining an open-plan format within an existing gallery space. Temporary enclosures were designed and constructed to allow these works to be displayed concurrently without significant disturbance to each other. Providing favorable room acoustics for the heavily amplified program within each space was also of primary importance. Panel absorbers tuned to the modal characteristics of each space as well as the unique acoustic characteristics of each work were integrated into the construction along with diffusive and absorptive surfaces to provide a comfortable listening environment for listeners while maintaining a uniform appearance.
Development of a low-frequency impact noise metric
Authors: Dong David W. , LoVerde John
Published: November 2013

Low frequency footfall noise (“thudding”) is a common source of complaints in lightweight joist-framed multifamily projects. Previous work by the authors has indicated that the low frequency impact sound pressure levels (LFISPL) from a standard ISO tapping machine are highly correlated with occupant reaction [LoVerde and Dong, J. Acoust. Soc. Am. 112, 2201 (2002), LoVerde and Dong, INCE Inter-Noise 2004 Proceedings, 167 (2004)]. In order to be useful, the raw LFISPL must be translated into a single number that maintains the high correlation with subjective reaction while providing adequate dynamic range to distinguish the performance of different assemblies. Candidate metrics are evaluated.
From sounds to meaning: Neural representation of calls in the avian auditory cortex
Authors: Elie Julie E. , Theunissen Frederic E.
Published: November 2013

Understanding how the brain extracts meaning from communication sounds is a central question in auditory research. Communication sounds distinguish themselves not only by their acoustical properties but also by their information content. To study how the auditory system could differentially treat signals that have different social meanings, we investigated in zebra finches (Taeniopygia guttata) the perception of vocalizations that are used in clearly distinct contexts. We first generated a vocalization library containing the entire repertoire of female and male zebra finches. We then investigated the neural representations of these social calls in primary and secondary auditory areas. Using both simple measures of spike rate and optimal decoding methods based on entire PSTH, we indentified 24% of 1400 single units selective for the different call categories. To further understand how neurons could process sounds to generate selective responses, we compared models of the neural response based on the acoustic properties of sounds and/or on the semantic values of calls. We found neurons that were very well explained by the simple semantic model. Combining these results with the anatomical properties of cells (positions and spike shapes) gives new insight into the neural representation of meaningful stimuli in the avian auditory neural network.
Neural processing of pressure and particle motion in central auditory pathways of larval bullfrogs
Authors: Simmons Andrea , Flores Victoria
Published: November 2013

The metamorphic transition from an aquatic to a terrestrial milieu considerably impacts the functioning of the anuran auditory system. Neural responses to underwater particle motion produced by z-axis vibration and to pressure waves transmitted through the air/water interface can be recorded from the tadpole’s dorsal medulla and torus semicircularis (auditory midbrain). Before metamorphic climax, these responses likely reflect stimulation of the saccule. Particle motion sensitivity in the dorsal medulla is stable in frequency range and sensitivity throughout larval development. In contrast, coding of both pressure waves and particle motion in the torus semicircularis is highly variable. There is a transient loss of pressure sensitivity in a short stage range (“deaf period”) prior to metamorphic climax, correlated with the development of the middle ear. Robust responses to particle motion are seen in the torus semicircularis during late larval stages and throughout the ”deaf period.” During climax, however, these responses are considerably degraded or lost completely. We interpret this second “deaf period” to reflect central neural, rather than peripheral mechanical, effects, likely related to rerouting of afferent pathways.
Advances in ultrasound methods for therapy
Authors: Hynynen Kullervo , Burgess Alison , O’Reilly Meaghan M. , Alkins Ryan , Pajek Daniel , Ellens Nicholas , Hughes Alec
Published: November 2013

Focused ultrasound has been shown to be the only method that allows noninvasive thermal coagulation of tissues and recently this potential has been explored for noninvasive image-guided drug delivery. In this presentation, the advances in ultrasound phased array technology for well controlled energy delivery will be discussed. In addition, some of the recent preclinical results for the treatments of brain tumors, stroke, and Alzheimer's disease will be reviewed. As conclusion, the advances in the image-guided focused ultrasound for the treatment of disease has been rapid and the future potential appears very promising.
Mechanism, monitoring, and drug delivery of the ultrasound-induced blood-brain barrier opening
Authors: Konofagou Elisa
Published: November 2013

Worldwide, neurodegenerative diseases account for more than 20 million patients. Aging greatly increases the risk of neurodegenerative disease while the average age of Americans is steadily increasing. Numerous small- and large-molecule drugs have been developed for treatment of neurodegenerative diseases but with mixed success. This is mainly because, when administered systemically in vivo, the blood-brain barrier (BBB) inhibits their delivery to the regions affected. Safe and localized opening of the BBB has been proven to present a significant challenge. Focused ultrasound (FUS) in conjunction with microbubbles remains the sole technique that can induce localized BBB opening noninvasively, selectively, and transiently. Over the past few years, our group has been able to unveil several aspects of the technology in order to (a) unveil the physical mechanism of opening, (b) maintain safety, (c) establish a non-MRI type of monitoring technique, (d) control the volume and permeability of opening through the microbubble used, (e) demonstrate large animal feasibility, and (f) determine the range of molecular sizes delivered. We have also shown that neurotrophic agents are capable of triggering downstream effects into the neuronal nucleus through the induced opening. All the aforementioned aspects including initial drug efficacy findings in large animals will be discussed.
The use of magnetic resonance-guided high intensity focused ultrasound to treat essential tremor
Authors: Elias William J. , Huss Diane , Voss Tiffini , Loomba Johanna , Khaled Mohamad , Frysinger Robert , Sperling Scott , Wylie Scott , Monteith Stephen , Druzgal Jason , Shah Binit , Harrison Madaline , Wintermark Max
Published: November 2013

Advances in ultrasound transducer technology have enabled for transcranial sonication with energy levels adequate to achieve tissue ablation. With MR-guidance and monitoring, precise lesioning is now possible of deep brain targets such as the thalamus and basal ganglia so that stereotactic lesioning is being reconsidered for the treatment of movement disorders. In this phase 1 clinical trial, we investigate the feasibility and safety of MRgFUS for performing a unilateral thalamotomy for medication-refractory essential tremor (ET). According to an FDA-approved protocol, 15 patients with medication-resistant ET underwent unilateral MRgFUS lesioning of the thalamus for dominant limb tremor. Intraprocedural monitoring was conducted with each incremental sonication using MR thermometry and clinical examination. Neurological assessments, validated tremor ratings, MRI, and quality of life data were recorded preoperatively and during a year post treatment. Adverse events were recorded throughout the study duration. Accurate thalamic lesioning was achieved in all cases. Dominant limb tremor subscores improved by nearly 75% while ipsilateral limb tremor was unchanged. Functional activities and quality of life measures improved significantly. Refining of the thalamic target was possible in five cases with subthreshold sonications. Serial MR imaging defined the evolution of the lesioning process.
First look: Acoustic calibration of carbon nanotube transducers
Authors: Huang Dehua , Howarth Thomas R.
Published: November 2013

Material researchers at the University of Texas at Dallas (UT-D) have recently been reporting on the development of underwater acoustic carbon nanotube (CNT) yarn sheets capable of high acoustic output at low frequencies with broad bandwidth. The principle transduction mechanism for their approach is through thermal acoustic means as opposed to conventional underwater transducers that utilize electromechanical vibrations. This presentation will begin with an overview of the CNTs including the design of a first generation packaging technique that was incorporated for the fabrication of three prototypes. The prototypes were acoustically calibrated in April 2013 at the US Navy acoustic calibration facility in Okahumpka, Florida. The presentation will include measured unbiased and biased transmitting voltage responses (TVRs) and directivity patterns over a two and a half decade band. Final discussions will include on-going research directions for further development. [Work supported by NAVSEA Division Newport.]
Tuning a combustive sound source to meet experimental needs
Authors: McNeese Andrew R. , Muir Thomas G. , Wilson Preston S.
Published: November 2013

The Combustive Sound Source (CSS) is a versatile underwater sound source used in underwater acoustics experiments. The source is comprised of a submersible combustion chamber, which is filled with a combustive gas mixture that is spark ignited. Upon ignition, the combustive mixture is converted into high temperature combustion byproducts, which expand and ultimately collapse to smaller volume than before ignition. Acoustic pulses are radiated by the bubble activity. The CSS can be used as a source for array calibration, propagation measurements, bottom characterizations, and sea floor seismic testing. Current environmental regulations and varying experimental needs require a tunable source that allows users to easily alter the source level, bandwidth, center frequency, and signal duration. Present efforts have focused on designing and testing a variety of devices that alter the resultant bubble activity to tune the radiated signals to meet various experimental needs. A new combustion chamber and gas exit ports have been constructed and tested in tank experiments. The results show that the resultant acoustic pulses can indeed be varied, and that tone bursts can be created. Discussions show how the device was tuned to meet specific needs for a particular application. [Work supported by ARL:UT Austin.]
An ultrasonic actuator working under cryogenic and vacuum circumstance
Authors: Chen Zhuzi , Chen Yu , Zhou Tieying , Fu Deyong
Published: November 2013

In this work, we present an ultrasonic actuator that can work under cryogenic vacuum environment. It can be used for adjusting distance between capacitor electrodes in high temperature superconductor filter (HTSF) to tune its pass-band. The actuator is an single crystal chips driven nut-type ultrasonic motor, which can work under cryogenic vacuum conditions. The stator of a nut-type ultrasonic motor is a nut-shaped octagon with internal thread, which matches with the rotor external thread and a bottom at one end as fixing base. Piezoelectric chips are glued to the sides of the octagon to generate a traveling wave along the circumference. Vibration of the stator drives the rotor to rotate via friction between thread interfaces and the thread drives the rotor to move along the axis direction. The actuator that we developed can easily acquire micrometer positioning accuracy, which enables it to tune the pass-band of a HTSF effectively. The motor was optimized with FEM harmonic response analysis. The mechanical characteristics and stepping precision of the prototype ultrasonic motor have been measured and discussed. [Work supported by NSFC.]
Underwater low frequency acoustic projector based on a musical instrument design
Authors: Acquaviva Andrew A. , Thompson Stephen C.
Published: November 2013

An electroacoustic projector that is small compared to the radiated wavelength presents a significant design challenge because its radiation resistance is small and the radiation impedance is highly reactive. Practical designs are often limited by high dynamic strain and high reactive drive currents. Wind musical instruments are also small compared to their lowest playing frequencies. However, wind musical instruments are not limited by the low radiation impedance. They use the low radiation impedance as a part of the regeneration mechanism that sustains the oscillation. This paper examines the hypothesis that an underwater projector designed to operate in water in the manner that a wind instrument operates in air may provide performance that is competitive with conventional electroacoustic low frequency acoustic projectors.
Just noticeable differential estimation of source-receptor dislocations in the auralization process
Authors: Murta Bernardo , Lins Jessica J. , Paul Stephan
Published: November 2013

The precision of source-receptor transfer functions is of importance to provide reliable and ecologically valid results in auralization. A test using paired comparison was developed to estimate the overall just noticeable differential (jnd) in signals obtained from the convolution of music with slightly varying source-receptor transfer functions. Subjects from 19 to 28 years, both male and female, were selected to participate comparing 24 sets of two sounds in each battery and answering if within each pair differences are noticeable. The signals were obtained by convolution of popular rock music with 12 s of duration with impulsive responses of different source-receptor positions in a scaled room and were divided in three batteries with different dislocation directions. To check subjects reliability pairs containing the same signals were also evaluated. The other 20 pairs were made by combinations of signals obtained by the FRF of the reference position and the FRFs of positions dislocated up to 10 cm from the reference point in a random manner. By analyzing the psychometric function, it was found that the jnd was reached when the receiver position was varied about 3 to 4 cm from the reference position. Further tests will be done to clarify details.
Autocorrelation analysis of lab-scale jets
Authors: Martin Kelly R. , Harker Blaine M. , Gee Kent L. , Neilsen Tracianne B. , James Michael M.
Published: November 2013

Autocorrelation (AC) analysis is useful in examining temporal relationships in a waveform and can be used to provide insight into properties of jet noise. Using techniques developed by Harker et al. [J. Acoust. Soc. Am. 133, EL458 (2013)] for full-scale jet data, AC analysis has been applied to unheated, laboratory-scale jet noise data. To more consistently compare the AC at various locations around the jet, it is important to account for the spatial variation in the spectrum by scaling with the peak frequency. In addition to this frequency scaling, the spatiotemporal variations in the autocorrelation are more plainly seen when an envelope function is applied. Calculated AC envelope functions from measured data are compared with theoretical curves for fine and large-scale jet noise radiation. Results are compared against those from a full-scale, military jet aircraft. [Work supported by ONR.]
A rapid computational method to investigate the directivities of quasi-omnidirectional sources of sound
Authors: Mortensen Jeshua H. , Leishman Timothy W.
Published: November 2013

While dodecahedron loudspeakers are widely used in acoustical measurements as quasi-omnidirectional sources of sound, other multiple-driver configurations may also be used for this purpose. Previous experimental work has shown that loudspeakers with higher-order Platonic solid geometries tend to produce higher omnidirectional cutoff frequencies than their lower-order counterparts. However, as their radiated fields transition from omnidirectional to multidirectional at higher frequencies, their directivities may or may not be closer to the omnidirectional ideal. Additional testing has been required to better understand the effects, but it has been cumbersome because of the difficulty of constructing and measuring many modified loudspeakers. This poster presents a practical method to estimate the directional characteristics of multiple-driver sources based on spherical enclosure geometries and the use of common mathematical software such as MATLAB. It enables one to easily and rapidly predict the directivity patterns of these sources and the effects of altered driver diameters, positions, numbers, vibrational patterns, and enclosure volumes. The method is shown to produce several interesting results that are validated by the boundary element method and experimental measurements.
Evaluation of a small variable-acoustics chamber for speech accommodation research
Authors: Calton Matthew F. , Leishman Timothy W. , Hunter Eric J.
Published: November 2013

Many studies have been conducted over the years to explore speech in rooms and its intelligibility to listeners. Speech accommodation by talkers is another developing field in speech and architectural acoustics. In some occupations, a talker’s voice is used nearly continuously throughout the workday. Acoustical conditions in the workplace can significantly affect vocal effort and the health and longevity of the vocal folds. Experimental resources are needed to better understand these conditions and how they may be optimized for the well-being of talkers. The present study investigates the range of acoustical conditions that may be established in a small variable-acoustics chamber for this type of research. The chamber is characterized using many pertinent room-acoustics parameters. Volunteers read passages in the chamber with no visual cues to impact their perception of its changing acoustical treatments. Various measurements were made to establish relationships between the room conditions and vocal efforts.
Investigating tonal spaces using an extension of VoiceSauce voice analysis software
Authors: Silverstein Kate , Yu Kristine M.
Published: November 2013

We extended VOICESAUCE (Shue, Keating, and Vicenik, 2009), a Matlab application which provides automated voice measurements over time from audio recordings, to include utilities for command line processing and testing. The command line utilities allow users to access core VOICESAUCE functionality, including batch processing of wave (*.wav) files and parameter manipulation, independently of a graphical user interface. The testing framework provides an automated process for tracking and measuring the effects of manipulating parameter settings across runs. In addition, we modified VOICESAUCE to be compatible with Octave and ported it to Python in order to facilitate use and development from a wider community. We use this software to compare the inclusion of phonation measures in the set of voice source parameters against f0 alone across White Hmong and Cantonese. Phonation, specifically breathy voice, plays a perceptual role in tone identification in both languages; however, in White Hmong, breathy voice is a necessary cue for accurate tonal identification (Garellek et al., 2012) whereas in Cantonese, phonation may facilitate perception but is not critical (Yu, 2011).
Significant infrasound levels a previously unrecognized contaminant in landmark motion sickness studies
Authors: Dooley Kevin A.
Published: November 2013

Airborne Infrasound at any given point can be accurately described as fluctuations or cyclic changes in the local barometric pressure. Variations in a motion sickness test subject’s elevation result in fluctuations in the surrounding barometric pressure by similar degrees to that experienced on a ship in high seas. Cyclic variation in the lateral or linear velocity of a subject in a vehicle or platform in atmospheric air may also be subject to infrasonic pressure fluctuations due to the Bernoulli principle and possibly vortex shedding effects. Calculations presented demonstrate that in at least one landmark study (McCauley et al., 1976) test subjects were exposed to infrasonic sound pressure levels in excess of 105 db at discrete frequencies between 0.063 and 0.7 Hz. The infrasonic sound pressure level necessarily present in cyclic motion in free atmospheric air does not appear to have been accounted for as a nausea influencing factor in the McCauley et al. (1976) motion sickness studies.
Tactical aircraft noise reduction using fluidic nozzle inserts
Authors: Morris Philip , McLaughlin Dennis , Lurie Michael , Karns Alex
Published: November 2013

The noise levels generated by tactical aircraft pose health hazards to personnel working in the vicinity of the aircraft (such as on an aircraft carrier deck) and are annoying to communities close to airbases. The engine exhausts are hot and supersonic and generally operate in an off-design condition, where the nozzle exit and ambient pressures are unequal. This results in shock cells in the jet plume. The interaction between the jet turbulence and the shock cells generates broadband shock-associated noise. The dominant noise radiation is in the downstream direction and is associated with the supersonic convection of turbulence in the jet. This paper describes the development of a technology to reduce both noise sources and involves the controlled injection of air into the diverging section of the nozzle to generate flow corrugations. This enables the jet to operate closer to its design condition and also breaks up the large scale turbulent structures that are responsible for the dominant noise radiation. Both flow and acoustic measurements are described. In addition, steady RANS computations provide information on the flow upstream of the nozzle exit and the effect of injector operating conditions on the flow field. Estimates of nozzle performance are also described.
High Skewness Infrasound from the eruption of Nabro Volcano, Eritrea: Comparison with supersonic jet and rocket engine data
Authors: Fee David , Matoza Robin S. , Gee Kent L. , Neilsen Tracianne B. , Ogden Darcy E.
Published: November 2013

An understanding of volcanic jets is critical to determining volcanic eruption column dynamics and mitigating volcanic hazards. However, volcanic jets are inherently difficult to observe directly due to their violence, opacity, and complex multi-phase and multi-component flow features. Recent work has shown similarities between the sound produced from explosive volcanic jets and man-made jet engines and rockets. We show that infrasound generated by the 2011 eruption of Nabro Volcano, Eritrea has high waveform skewness and similar waveform statistics to sound produced by supersonic jet engines and rockets. The infrasound from Nabro reported here strongly indicates that infrasound from some volcanic eruptions is produced in similar ways to man-made jet noise from heated, supersonic jet engines and rockets. Noise sources and flow dynamics of jet engines and rockets are better characterized and understood than volcanic jets, suggesting volcanologists could utilize the modeling and physical understandings of man-made jets.
Nonlinear sound propagation associated with a high mass flow cold jet
Authors: Marshall Andrew , Evans Neal
Published: November 2013

It is well-known that aircraft and rocket engines produce high amplitude broadband noise, but such noise can also be generated by high-pressure gas venting from piping systems. Compared to rocket and jet engines, however, the gas exiting these systems can be very low in temperature. During a recent full-scale blow-down test at Southwest Research Institute, noise measurements of a cold jet were obtained. High pressure gas was forced through a valve, pipe, and nozzle system to simulate a natural gas blow-down event in order to measure stresses at welded connections. Nitrogen gas flowed vertically through a 50 cm nozzle with an average mass flow rate of 27.7 kg/s. Noise measurements were made perpendicular to the jet direction at two ranges (18.3 and 157 m). Peak amplitudes of 155 and 138 dB were obtained at the near and far range, respectively. A comparison between this data and rocket engine measurements from the literature will be discussed, including indicators of nonlinear propagation.
Aeroacoustic source measurement methods for characterizing the sound generated by ducted flow devices with higher-order modes
Authors: Newman Timothy J. , Agarwal Anurag , Dowling Ann P. , Desvard Ludovic
Published: November 2013

The International Organization for Standardization (ISO) method 5136 is widely used in industry and academia to determine the sound power radiated into a duct by fans and other flow devices. The method involves placing the device at the center of a long cylindrical duct with anechoic terminations at each end to eliminate reflections. A single off-axis microphone is used on the inlet and outlet sides that can theoretically capture the plane-wave mode amplitudes but this does not provide enough information to fully account for higher-order modes. In this study, the ”two-port” source model is formulated to include higher-order modes and applied for the first three modes. This requires six independent surface pressure measurements on each side or ”port.” The resulting experimental set-up is much shorter than the ISO rig and does not require anechoic terminations. An array of six external loudspeaker sources is used to characterize the passive part of the two-port model and the set-up provides a framework to account for transmission of higher-order modes through a fan. The relative importance of the higher-order modes has been considered and their effect on inaccuracies when using the ISO method to find source sound power has been analyzed.
Ballistic shock wave localization estimation of shooter position and velocity using difference of time of arrival (DTOA) algorithm in orthogonally arranged discrete acoustic arrays: Part II
Authors: Korman Murray S. , Sarkady Antal A.
Published: November 2013

A mathematical algorithm was developed to estimate the parameter space involving both the displacement of the shooter with respect to the array and the velocity of the projectile using the difference in time of arrival, DTOA, of the ballistic shock wave cone at each position of an N-element array. [J. Acoust. Soc. Am. 133, p. 3506, May 2013.] The array geometry involves orthogonally arranged discrete point-like line arrays using wide-band microphone or piezo-electric elements. The algorithm utilizes a nonlinear least squares parameter fit by summing the squares of [DTOA (experimental)—DTOA (theoretical parameters)] values where the DTOA (theoretical) equation involves a lengthy Taylor series expansion of the exact “difference in time of arrival” theoretical equation. Earlier results, in the absence of noise (N = 7) showed that the model has good versatility in estimating displacement (location) and velocity in simulated computer trials. Here, near-field noise is simulated by a rotor blade resulting in uncertainty in the arrival time of the shockwave at each sensor, leading to uncertainty in the estimation of the fit parameters. For example, simulated scatter plots of the azimuthal angle vs the elevation angle parameters for different projectile miss distances become useful in computing parameter uncertainty for different signal-to-noise ratios.
Hypersound in simple one-dimensional device structures
Authors: Andrews G. Todd
Published: November 2013

Brillouin spectroscopy, an inelastic laser light scattering technique capable of probing long wavelength acoustic phonons in a variety of material systems, was used to study hypersound in simple one-dimensional mesoporous silicon-based device structures formed using electrochemical etching methods. Brillouin spectra of porous silicon superlattices with binary periodicity on the order of the hypersound wavelength reveal zone folding, band gaps, and localized modes, indicating that these structures behave as hypersonic phononic crystals. Superlattices with smaller modulation wavelengths act as effective elastic media. New results on the behavior of hypersound in stacked superlattices and those with deliberately introduced defects will also be presented. Collectively, these studies have led to an improved fundamental understanding of classical wave behavior and interaction in low-dimensional systems and open up exciting opportunities for phonon engineering in a silicon-based platform.
Noise reduction performance of wheel and rail vibration absorbers
Authors: Bergen Thom , Nelson James T.
Published: November 2013

The rolling noise reduction effectiveness of wheel and rail vibration absorbers was evaluated at Trimet in Portland, Oregon. Tests included tangent ballast and concrete tie track and curved track slab track with bi-block concrete ties. Under-car noise data were recorded throughout the system with and without wheel vibration absorbers. Results of the rolling noise tests are summarized for various combinations of treated and untreated rails and wheels. The wheel and especially the rail vibration absorbers significantly reduced rail vibration at audio frequencies, but had little effect on wayside rolling noise. Wayside noise at tangent track was slightly higher with rail vibration absorbers than without. However, the “singing rail” noise was eliminated entirely. The “singing rail” vertical vibration transmission spectrum had a pass-band characteristic as expected for periodic supports. The vibration data indicate that above 250 Hz the wheel was the dominant source of noise relative to the rail. A reduction of stick-slip noise was observed over most curves, though results were inconsistent.