bluuebunny/crossref_metadata_2025 huggingface dataset:
Gunshot recordings from a criminal incident: Who shot first?
Authors: Maher Robert C.
Published: May 2016

Audio forensic examination for law enforcement and criminal justice investigations increasingly involves audiovisual recordings from dashboard camera systems, bystander smart phones, body cameras worn by police officers, and even by cameras built into TASER™ devices. If the camera is pointing in an appropriate direction the details of the incident may be found in the recorded video. However, if the camera’s field of view is limited, it may still be possible to evaluate the circumstances of interest by examining the sounds captured by the recording device’s microphone. This paper presents audio examples in which the forensic examiner must attempt to address questions such as: How many gunshots took place? What types of firearms were involved? Who shot first? Audio examples are presented to demonstrate the solutions—and mysteries—found in several real world cases.
Shot in the dark: Physical and psychophysical limitations on shooter identification from earwitness testimony
Authors: Summers Jason E.
Published: May 2016

While human listeners have a remarkable ability to determine the cause of a sound and the location of the sound source using only their sense of hearing, this ability is subject to errors and lack of certainty due to factors that are grounded in well-understood phenomena in physics and psychoacoustics. In this talk, the author will describe his experience serving as an expert witness for the defense in a criminal trial concerning an incident that took place in a dark outdoor location in which a shot was allegedly fired by one of two suspects. The defendant was alleged to be the shooter based upon earwitness testimony regarding the direction from which the shot was heard to have originated. Three key questions brought out in the forensic analysis performed for the trial will be addressed from the perspective of signal-detection theory considering both physical factors (e.g., outdoor blast and shockwave propagation) and psychophysical factors (e.g., auditory detection and classification and spatial-hearing acuity): (1) Was the gunshot audible? (2) Was the sound that was heard identifiable as a gunshot? (3) With what accuracy and precision could the location of the gunshot be determined?
Toward validation of shear wave elastography using vibration rheometry in soft gels
Authors: Yengul Sanjay S. , Madore Bruno , Barbone Paul E.
Published: May 2016

Shear wave propagation is at the heart of several elastography methods designed to quantify the elastic properties of living tissues. These differ in excitation mechanism, imaging modality, volume of tissue being sampled, and the diagnostic output [Parker et al. PMB, 2011]. Some of these techniques are already available to clinicians as diagnostic tools for the identification of pathology, particularly in the diagnosis of liver fibrosis. However, these techniques work in different parameter regimes, making it difficult to quantitatively compare different elastography modalities. As a result, the critical cutoffs for fibrosis staging are system dependent [Ferraioli et al. WFUMB, 2015]. We present progress toward a framework to allow quantitative comparison of different viscoelastic measurement techniques, including shear wave based elastography (SWE) methods (e.g., acoustic radiation force based SWE and magnetic resonance elastography), and a novel vibration rheometry of gel phantoms. In so doing, we seek to account for frequency and temperature dependence of material properties, as well as control for other confounding factors such as water content, material aging, boundary conditions, awkward sample geometries, and batch-to-batch gel variations.
Bone demineralization assessment using acoustic radiation force
Authors: Denis Max , Wan Leighton , Cheong Mathew , Fatemi Mostafa , Alizad Azra
Published: May 2016

In this work, an ultrasound-guided remote measurement technique is proposed for bone demineralization assessment. Utilizing an acoustic radiation force (ARF) beam as our excitation source and a receiving hydrophone, the mechanical properties of a bone can be noninvasively assessed. Focusing the ARF beam on the bone surface acts as point force generating vibrational waves. Coupling the bone surface and hydrophone, the ensuing radiating acoustic pressure from these vibrational waves are captured for analysis. Of particular interest, are the features best related to the bone’s mechanical properties. Conducting ex-vivo experiments demonstrated that the velocity feature best delineates intact and demineralized bones. The typical velocity of an intact bone (3000 m/s) is higher in comparison to a 72 h demineralized bone (1600 m/s). According to the receiver operating characteristic (ROC) curve, the optimal velocity cut-off value of 3096 m/s yields 80% sensitivity and 82.61% specificity between the intact and demineralized bones. Other features, such as the spectra of the demineralized bones’ acoustic response, exhibited higher attenuation for frequencies below 200 kHz in comparison to the intact bones. A time-frequency analysis demonstrated a frequency shift with demineralization. These results demonstrate the potential application of our proposed technique for monitoring bone demineralization.
Jet formation of contrast microbubbles in the vicinity of a vessel wall
Authors: Mobadersany Nima , Sarkar Kausik
Published: May 2016

Behaviors of microbubble contrast agent near a vessel wall under ultrasound excitation are investigated using a boundary integral method. Ultrasound in the presence of microbubbles facilitates drug delivery by streaming and jetting phenomena. The microbubbles are encapsulated by a layer of proteins or lipids to stabilize them against dissolution. The encapsulating shell of the contrast microbubble is viscoelastic modeled here by three different interfacial rheological models. While at low excitations microbubbles undergo regular oscillations, at high amplitudes excitation, they form jets toward the wall. The dynamics and the resulting shear stress on the wall are studied varying the shell rheology and other relevant parameters of the problem.
Effects of ultrasound in presence of microbubbles on cartilage tissue regeneration in three-dimensional printed scaffolds
Authors: Aliabouzar Mitra , Zhang Lijie G. , Sarkar Kausik
Published: May 2016

Gas-filled microbubbles encapsulated with lipids and other surfactants are highly responsive to ultrasound, which has led to their effective role as ultrasound contrast agents (UCA). In this study, for the first time, we used lipid-coated microbubbles (MB) prepared in-house in order to better harness the beneficial effects of ultrasound stimulation on proliferation and chondrogenic differentiation of human mesenchymal stem cells (MSCs) within a novel 3D printed poly (ethylene glycol) diacrylate (PEG-DA) hydrogel scaffolds. A significant increase in cell number (p <0.001) was observed with low intensity pulsed ultrasound (LIPUS) treatment in the presence of 0.5 % (v/v) MB after 1, 3, and 5 days of culture. MSC proliferation enhanced up to 40% after 5 days of culture in the presence of MB and LIPUS while this value was only 18% when excited with LIPUS alone. We investigated the effects of acoustic parameters such as excitation intensity, frequency, and pulse repetition period on MSC proliferation rate. Our 3-week chondrogenic differentiation results demonstrated that combining LIPUS with MB significantly enhanced both Glycosaminoglycan (GAG) and type II collagen production. Therefore, integrating LIPUS and MB appears to be a promising strategy for enhanced MSC growth and chondrogenic differentiation.
Microbubble response to dual frequency excitation for broadband contrast imaging
Authors: Keravnou Christina , Papantonis Chrysovalantis , Averkiou Michalakis
Published: May 2016

Contrast imaging relies on pulsing schemes like pulse inversion (PI), power-modulated pulse inversion (PMPI), and power modulation (PM) to isolate certain harmonic components. These multi-pulse schemes normally employ single frequency pulses (SFP). In this work, we propose dual frequency pulses (DFP) coupled with pulsing schemes (PI, PMPI, and PM) for microbubble imaging. The proposed DFP contain an amount b1 of a fundamental frequency f and an amount b2 of its phase-shifted (φ) second harmonic 2f. Microbubbles were excited with a variety of DFP combinations (b1, b2, φ) and their nonlinear response was compared to that from conventional SFP. All pulsing schemes benefit in terms of overall signal from the use of DFP by ~4–6 dB. PI benefits the most when coupled with DFP as it extracts an additional amount of nonlinear fundamental signal (~25 dB) something not feasible with SFP. It was observed that microbubble nonlinear response changes when the relative amount of f and 2f in DFP change, allowing the design of specific pulses for different microbubbles. In conclusion, since the use of DFP with pulsing schemes extracts harmonics more efficiently than SFP it has the potential to improve contrast imaging in terms of bubble sensitivity and image resolution.
Efficient dispersion analysis of guided waves in laminated composites and substrates
Authors: Vaziri Ali , Guddati Murthy N.
Published: May 2016

Nondestructive testing of laminated composites and substrates involve matching observed and predicted dispersion characteristics of guided waves. These characteristics are quantified through dispersion curves (phase velocity versus frequency) and need to be computed for a large number of estimated structure and material property combinations. Given its central nature, we propose an efficient approach for computing the dispersion curves, leading to an order of magnitude savings in the computational cost. Our approach is based on conventionally used finite element semi-discretization through the depth, but with one significant modification: by using a specially designed set of complex-valued finite element lengths through the depth, we show that the dispersion curves can be obtained with a handful of elements per layer as opposed to larger number of traditional finite elements, resulting in large reduction in computational effort. In this talk, we present the formulation of the proposed complex-length finite element method and illustrate its efficiency through modeling wave dispersion in laminated composites and substrates. Finally, we introduce an inversion procedure developed around this method and demonstrate its effectiveness in characterizing plate structures using synthetic as well as real nondestructive testing data.
Analysis of the error sources of the two-microphone transfer function method for measuring absorption coefficient in the free field using numerical modeling
Authors: Hall Hubert S. , Vignola Joseph F. , Judge John A. , Turo Diego
Published: May 2016

Extension of the two-microphone transfer function absorption coefficient measurement technique from impedance tubes to the free field introduces several error sources. The three-dimensional nature of the sound field necessitates consideration of factors that are not relevant in an enclosed tube below the cutoff frequency. The impedance tube technique has been modified to account for non-planar wave propagation due to an acoustic point source. The sound field contamination from sample edge diffraction has generally restricted use of the technique to frequencies such that wavelengths are small relative to sample dimensions. This requires the use of very large test panels for low frequencies. Numerical models of the two-microphone free field technique have been created to quantify these effects. Each effect was isolated to better understand its independent impact on the accuracy of the technique. Finally, a series of experimental tests were conducted to validate the numerical modeling results.
An open-access interactive textbook for teaching room acoustics modeling
Authors: Savioja Lauri
Published: May 2016

There are several different techniques for modeling room acoustics. Interactive visualizations can be used to ease learning the main principles and algorithms for that. This presentation will demonstrate a new interactive open-access textbook aiming to support learning the basics of room acoustics modeling techniques. The visualizations illustrate how different algorithms work in simple 2-D geometries, and what are the underlying assumptions in each of them. Interactivity here means that the students have control over both various parameters that affect the modeling performance and accuracy, and the geometries. They can study how the modeling results change in response to such changes. The main emphasis here is on geometrical room acoustics, and the techniques based on that: image-source model, ray-tracing, and acoustic radiance transfer, but the longer term aim is to cover all the main room acoustic modeling principles and techniques.
The sound of STEAM (science, technology, engineering, arts, and math): Acoustics as the bridge between arts and STEM (science, technology, engineering, and math)
Authors: Goates Caleb , Whiting Jenny , Berardi Mark , Gee Kent L. , Neilsen Tracianne B.
Published: May 2016

This paper describes the development and presentation of a Science, Technology, Engineering, Arts, and Math (STEAM) workshop for elementary school teachers designed to provide ideas and tools for using acoustics in the classroom. The abundant hands-on activities and concepts in acoustics naturally link science and music in an intuitive way that can assist teachers in moving forward on the STEAM initiative. Our workshop gave teachers an introduction to acoustics principles and demonstrations that can be used to tie STEAM techniques in with Utah State Education Core standards. These hands-on demonstrations and real-world applications provide an avenue to engage students and support learning outcomes. Feedback indicated that the participants learned from and enjoyed the initial implementation of this workshop, though many elementary school teachers did not immediately see how they could integrate it into their curriculum. While additional efforts might be made to better focus the training workshop for the K-6 level, curriculum developers need to appreciate how acoustics could be used more broadly at the elementary school level if the emphasis changes from STEM to STEAM.
A new acoustics research group and course at Brigham Young University—Idaho
Authors: Johnson Jon P. , Gee Kent L. , Nielson Ryan
Published: May 2016

This paper details the beginning of a collaboration between the Acoustics Research Group at Brigham Young University in Provo, UT, and a new research group at BYU-Idaho in Rexburg, ID. BYU-Idaho is a four-year university without a graduate program. Its physics program awards 10 to 15 BS degrees in physics each year. Historically, only a 100-level acoustics course has been offered by the physics department, but in conjunction with forming this new research group we are hoping to construct an upper-division acoustics course assuming a background in differential equations, computational physics, and Fourier analysis. An overview of the collaboration, which is still in its infancy, is discussed.
Vocal registers and comparative frequency analysis for multiple sung genres
Authors: Popeil Lisa
Published: May 2016

Diverse vocal genres utilize different registration and resonance strategies. This presentation will analyze and compare sound samples from numerous sung genres including classical (male versus female), pop, R&B, rock, country and various musical theater belting substyles (heavy belt, nasal belt, ringy belt, brassy belt, and speech-like belt). In addition, using acoustic analysis, these styles will be demonstrated by a single subject to show how registration and resonance choices can be made to clarify, identify, and codify the conventions of that genre.
Listener ratings of singer expressivity in musical performance
Authors: Parrott Mackenzie L. , Nix John
Published: May 2016

Vocal fry has gained a lot of attention in recent years from speech language pathologists, linguists, singers, researchers, and the general public alike. Vocal fry register uses low airflow through shortened vocal folds, causing an aperiodic pattern in vocal fold oscillation. This vocal mannerism is becoming increasingly common in American speech, fueling discussion about the implications and perception of its use. As it has become more prevalent, fry has naturally found its place in many commercial American song styles as well. Many singers are implementing fry as a stylistic device at the onset or offset of a sung tone. The objective of this study is to analyze whether listeners’ ratings of a singer’s expressivity in musical samples in two contemporary commercial styles (pop and country) are affected by the presence of vocal fry. We hope that this study will shed some insight into the prevalence of this particular vocalism in popular music, and to see if there is a difference in listener ratings according to the singer’s gender.
Toward mapping voice registers in the physiological domain: A computational study
Authors: Zhang Zhaoyan
Published: May 2016

Although there have been many studies on the acoustics and vibration of voice registers, the underlying physiological mechanisms of different registers still remain unclear. This study represents a preliminary effort toward identification of regions in the physiological domain that would lead to different voice registers, using a computational phonation model. The physiological parameters under consideration include vocal fold geometry, stiffness, resting glottal angle, subglottal pressure, and vocal tract shapes. Three registers are considered, including vocal fry, chest, and falsetto. Voice registers are identified based on known or reported acoustic features, including F0, closed quotient, and harmonic structures, based on which the physiological conditions corresponding to each voice register are determined. Preliminary perceptual experiment will be performed to confirm register identification. [Work supported by NIH.]
Evaluation of smartphone sound measurement applications using external microphones—A follow-up study
Authors: Kardous Chucri A. , Shaw Peter B. , Murphy William J.
Published: May 2016

The National Institute for Occupational Safety and Health (NIOSH) conducted a follow-up study to examine the accuracy of smartphone sound measurement applications (apps) using external, calibrated, microphones. In the initial study, we examined 192 apps on the Apple (iOS) and Google (Android) platforms. Overall, 10 iOS apps met our selection criteria for occupational noise exposure measurements, and of those, only 4 iOS apps (SoundMeter, SPLnFFT, SPL Pro, and NoiSee) were within ±2 dB(A) of a reference microphone. For this study, we selected the same 4 iOS apps and examined their accuracy and performance using the MicW i436 and the Dayton Audio iMM-6 external microphones. The MicW i436 microphone is marketed as compliant with IEC-61672 class 2 sound level meter standard. Testing was conducted in a reverberant chamber using pink noise over seven nominal sound levels from 65 to 95 dB. The results showed an even closer agreement than the earlier study, with mean differences within ±1 dB(A) of the reference microphone. This study suggests that the use of external microphones, and the ability to calibrate the microphones and apps, improves the overall accuracy and precision of measurements, and removes many of the constraints and limitations associated with the built-in smartphones’ microphones.
Assessment of noise exposures for pre-term infants during air transport to neonatal intensive care units using iPhone sound meter apps
Authors: Clark William W. , Saunders Scott
Published: May 2016

A significant number of infants born prematurely or with life-threatening conditions in local hospitals require transport to a regional tertiary care center. St. Louis Children’s Hospital’s (SLCH) neonatal intensive care unit (NICU) serves southern Missouri and Illinois, and 3000 pre-term neonates are transported to the hospital annually, most by helicopter or fixed wing aircraft. This initial study evaluates the accuracy and efficacy of using an iPhone app (SoundMeterPro,Faber Acoustics) for routine collection of infants’ noise exposures inside the isolette during air transport. The app was downloaded onto iPhones (4,6S) calibrated in a sound field using a Larson-Davis type I sound level meter (831). The meter and the iPhones were placed inside an unoccupied isolette and recorded in-flight noise levels during the outbound portion of trips from the NICU to the local hospital. Sound levels were high (85–90 dBA) and higher during take-off and landings or when the isolette lid was opened, and level and OBN measures obtained with the SoundMeterPro app were similar to those from the type 1 SLM. An additional advantage of the iPhone SLM platform for routine use in aircraft is that it does not require FAA certification for each aircraft, if used in the airplane mode.
2015 Jacksonville Executive at Craig Airport noise study
Authors: Matthews Herbert R. , Stephenson Ross
Published: May 2016

This research will update outdated information as identified in the original 2006 Federal Aviation Regulation (FAR) Part 150 Study of Craig Municipal Airport. The original study conducted an evaluation of the Airport’s existing noise conditions from 2004 to 2005 to determine if current voluntary operational procedures were achieving their desired effect, and identified other opportunities to reduce aircraft-related noise impacts on the communities surrounding the airport. This study will examine and revalidate the findings of the original 2006 study. It is expected that the noise level contours, as depicted within the original study, have reduced in size since 2006. This is due to the utilization of more technically advanced aircraft engines on today’s modern business jets. Airport noise magnitude, frequency, and duration will be measured during daily operations. Sound exposure level (SEL) metric used by the Federal Aviation Administrations will be used to measure single event noise exposure levels along with time weighted cumulative noise metrics. The findings of the study may provide the opportunity for the Jacksonville Airport Authority (JAA), the aviation industry, affected political jurisdictions and airport neighbors to work together in the evaluation of potential noise reduction and land use control measures.
Real-time sound measurements of exercise classes with mobile app demonstrate excessive noise exposure
Authors: Sinha Sumi , Kozin Elliott D. , Naunheim Matthew R. , Barber Samuel R. , Wong Kevin , Katz Leanna W. , Stefanov-Wagner Ishmael J. , Remenschneider Aaron K.
Published: May 2016

Noise induced hearing loss is a major contributor to observed hearing impairment in the general population. Advanced mobile technology now allows the opportunity to directly measure noise exposure profiles on an individual basis. Herein, we conduct a pilot study to determine noise exposure in popular gym-based exercise cycling classes where music and equipment generate high intensity sound. A calibrated iOS mobile app (SoundMeter, Faber Acoustical) coupled to a microphone was used to measure noise in a random sampling of similar indoor cycling classes (n = 7). The average length of exposure was 52.33 ± 3.81 min. Maximum sound levels recorded across all classes were 125.96 dB and averaged 119.6 ± 3.5 dBA. By NIOSH standards, 31.5 ± 14.7 min were spent over 100 dBA, corresponding to a class daily exposure dose of 191% ± 1.2%. The 8-h projected dose was 1781% ± 11.9%. Preliminary data suggest that certain exercise classes may expose participants to excessive, potentially dangerous sound levels. The use of readily accessible mobile technology can assess noise exposure risk from the consumers’ perspective, allowing a new level of independent self-monitoring of noise and empowering individuals to become active participants in their hearing health.
The effectiveness of resilient sports flooring on noise from crossfit activities
Authors: Golden Matthew V. , Gartenburg Paul
Published: May 2016

Crossfit facilities in dense, multi-use facilities are growing in numbers every day. Even minimally sensitive receivers can be very significantly impacted by Crossfit activities. Consequently, vibration and vibration induced noise in structures as a result of heavy weight drops are a never ending issue. This paper compares data recorded from heavy weight drops in an ASTM E492 floor/ceiling testing suite. The resultant sound pressure level in the receiving room and vibration levels in the structure are measured. Several different standard and high performance resilient sports floorings are compared. These sports floors are tested on single concrete slabs as well as various floating slabs. The floating slabs include continuous rubber underlayments, discrete rubber isolators and spring jack-up floating floors. In addition, laboratory impact and airborne isolation performance results of a spring jack-up floating floor are reported.
Impact of heavy weight drops at Crossfit® training facilities on adjacent doctor’s examination rooms and on conference rooms
Authors: Pettyjohn Steve
Published: May 2016

Significant sound and vibration are generated when members of Crossfit® training facilities drop heavy barbell weights to the floor from waist or shoulder height. Weights between 40 kg (90 lbs) and 100 kg (225 lbs) are repeatedly lifted from the floor to should height, then dropped to the floor and then picked up again. Crossfit® combines a variety of exercises using weights, pull up bars, and tires for dragging to increase the strength of participants. The sound and vibration generated by dropping of the weights is the only activity that has generated strong reaction from adjacent spaces. The Crossfit® facilities are found in many spaces, but often in warehouse/office or strip offices, i.e., locations with many types of tenants. Examples are Crossfit® facilities next to optometrists, conference rooms, and massage parlors. The sound and vibration generated by the weight drops and resulting sound and vibration in the receiver space are presented for several conditions of the equipment and the floor. Several options for reducing the transmission of excessive sound and vibration into adjacent spaces is presented. These include modifications to the weights, floor toppings, floor dimensions, and wall construction.
Investigation of acoustical environment of multi-story buildings in Korea for applicability of EN 12354
Authors: Kim Sung M. , Lim Hansol , Jeon Jin Y.
Published: May 2016

In multi-story buildings, sound reduction can be evaluated using sound prediction model defined in the EN 12354 in Europe generally. The reduction model deals with the calculation and evaluation of direct and flanking transmission between two rooms through each structure elements for example the floor, ceiling, inner wall, or etc. In case of Korea, general residential type of is multi-story building so the noise transmission between neighbors is the most well-known acoustical problem. The EN 12354 can be considered as an important evaluation method, however the acoustic environment in Korea should be considered for the applicability of prediction model. Therefore, acoustical environments of multi-story buildings were investigated using field survey in order to evaluate the applicability through EN 12354.
Vortex beams and radiation torque for kidney stone management
Authors: Maxwell Adam D. , Bailey Michael , Cunitz Bryan W. , Terzi M. , Nikolaeva A. , Tsysar S. , Sapozhnikov Oleg A.
Published: May 2016

Our team previously developed an instrument to reposition kidney stones with acoustic radiation force. In a clinical trial, the technology was used to transcutaneously facilitate passage of small stones and to relieve pain by dislodging obstructing large stones. Acoustic trapping and manipulation of kidney stones in water has recently been investigated using both single element and sector arrays in the range of 0.3–1.5 MHz. Experimental holographic reconstruction of the transducer surface velocity confirmed the proper operation of each transducer. Human stones approximately 5 mm, as well as glass and aluminum beads, were placed on a flat tissue phantom in a water bath. During exposure, stones were drawn to the beam axis, and then controllably translated along the surface in any direction transverse to the beam. The phase between sector elements could be used to control the vortex size, as well as rate and direction of rotation of the trapped object. The trapping effect was disrupted at increased transducer output, possibly by generation of acoustic streaming. In conclusion, a method was tested for transverse acoustic trapping of kidney stones with vortex beams. [This work was supported by RBBR 14-02-00426, NIH NIDDK DK43881, DK104854, and DK092197, and NSBRI through NASA NCC 9-58.]
Enhancement of spectral contrast and spectral changes as approaches to improving the intelligibility of speech in background sounds
Authors: Moore Brian C.
Published: May 2016

Cochlear hearing loss is accompanied by reduced frequency selectivity, which contributes to problems in understanding speech in background sounds. The excitation pattern evoked by sounds like vowels is “flatter” in an impaired ear than in a normal ear. Two approaches to partially compensating for the effects of reduced frequency selectivity are described. The first uses spectral contrast enhancement on a frame-by-frame basis. Only features of the short-term spectrum that would be represented in a normal ear are enhanced. Experimental evaluations of this approach showed that it could improve the intelligibility of speech in noise by a small amount, but that this required a fine frequency analysis, in turn requiring relatively long frames and time delays that might be too long for use of the method in hearing aids. A second approach enhances spectral changes over time, based on the idea that information is speech is carried by spectral changes. This approach also led to modest improvements in the intelligibility of speech in noise, especially when the amount of enhancement was made to vary with frequency depending on the hearing loss at that frequency and when the parameters of the processing were selected for each individual using a genetic algorithm.
A longitudinal study of the effects of aging on speech breathing: Evidence of decreased expiratory volume in speech recordings
Authors: Graetzer Simone , Hunter Eric J.
Published: May 2016

Age-related changes occur in speech that are associated with structural, physiological, and immunological processes involving the oral and nasal cavities, the larynx and pharynx, and the respiratory system. With aging, laryngeal tissues tend to degenerate or atrophy and laryngeal cartilages tend to ossify. These changes can lead to increased instability and perceived hoarseness or harshness, reduced loudness, and changes in fundamental frequency. In the respiratory system, a decline in lung and diaphragm elasticity and muscle strength can occur, and the thoracic cage can stiffen, leading to reductions in lung pressure and forced expiratory volume (hence, an increase in residual lung volume). In this study, recordings of three female and three male subjects were analyzed. These were made over the course of between 18 and 48 years (with a mean of 32.5 years). Samples of five minutes in length were extracted from each recording. Subsequently, trained raters measured the durations of exhalations during speech (termed “breath groups”). The results indicate decreases in breath group duration for most subjects as their age increased (especially from 65 years onwards), consistent with the decline in expiratory volume reported in the literature.
Vocal matching in interactions between mothers and their normal-hearing and hearing-impaired twins
Authors: Kondaurova Maria V. , Dilley Laura C. , Bergeson-Dana Tonya R. , Fagan Mary K.
Published: May 2016

Vocal matching, the ability to imitate phonetic properties of speech, was examined in interactions between mothers and their normal-hearing (NH) and hearing-impaired twins who used hearing aids (HAs) or a cochlear implant (CI). Vocalizations of three mother-twin triads were recorded in three sessions over 12 months. In one triad, the twins were 15.8 months old and NH. In another triad, the twins were 11.8 months; one was NH while the other had HAs. In the third triad, both twins were 14.8 months; one was NH while the other had a CI. A vocal match was defined as an instance of perceptual and acoustic similarity between adjacent maternal and infant utterances in relation to pitch height and contour, utterance duration, rhythm, or vowels and consonants. Reciprocal vocal matching occurred in 28% to 38% of infant vocalizations across triads. At session three, CI and HA infants’ reciprocal vocal matches increased compared to two previous sessions and to those of NH siblings; reciprocal vocal matches in the NH dyad decreased over time. The results suggest that vocal matching is a part of linguistic interactions between mothers and their NH and HI infants and that pediatric hearing loss affects mothers’ and infants’ imitative abilities.
Clear speech benefits for perception of center-only and edge-only syllables
Authors: Luque Jenna S. , Maxfield Nathan , Lister Jennifer J. , Rogers Catherine L.
Published: May 2016

Clear speech is a speaking style that has been shown to enhance intelligibility in noise; however, the underlying reasons for this enhancement are less well understood. One hypothesis is that listeners require less acoustic information to identify syllables spoken in clear than in conversational speech, allowing them to make use of briefer dips in fluctuating noise. The present study tests this hypothesis by presenting six /bVd/ syllables (“bead, bid, bed, bayed, bad,” and “bod”), produced in clear and conversational speech styles, to 20 monolingual native English-speaking listeners in a six-alternative forced-choice task. These syllables were modified to present varying portions of the syllable to listeners (20, 40, 60, or 80 ms of the syllable preserved). First, center-only syllables were created, in which acoustic information around the vowel midpoint was preserved. Second, edge-only syllables were created, in which information from the vowel center was silenced and formant transitions preserved, with vowel duration either maintained or equalized. Preliminary results show some clear-speech benefits in the partial-syllable conditions, with benefits mainly at shorter gates for center-only syllables and mainly at longer gates for edge-only syllables. Implications for understanding the source of clear-speech benefits in noise and phoneme perception more generally will be discussed.
The role of the carrier waveform in vocoded Mandarin speech perception with applications to cochlear implants
Authors: Schiltz Jessica H. , Berisha Visar
Published: May 2016

Cochlear implants (CI) enable patients to perceive sound by the generation and transmission of electrical impulses. Voice encoded (vocoded) audio is commonly used as a simulator of CI speech. Past studies of vocoded English concluded that coded speech intelligibility is independent of whether a sinusoidal or noise-based carrier is used. Based on this work, recent CI research for tonal languages like Mandarin, have opted for a sinusoidal carrier without considering the impact of the carrier on intelligibility. The importance of spectral cues in Mandarin speech necessitates further analysis of the relationship between the carrier and intelligibility. This study explored intelligibility differences between English and Mandarin vocoded speech. This approach assessed speech recognition of randomly presented phrases to normal hearing English and Mandarin listeners. Available frequency channels and carrier type were varied to compare their effects on Mandarin word and tone identification. Results indicated that audio processed with a sinusoidal carrier led to significantly lower Mandarin intelligibility scores. In comparison, no effect was observed between English and Mandarin intelligibility when a noise-based carrier was used. The data suggest that the nature of the carrier type affects tonal language intelligibility and warrants further research as an experimental consideration in vocoded speech studies.
Spectral contrast effects in vowel categorization by listeners with sensorineural hearing loss
Authors: Stilp Christian , Alexander Josh
Published: May 2016

The auditory system is highly sensitive to changes in acoustic input. This is especially true for sounds with relatively stable (reliable) spectral properties across time. Over a limited range, changes to the spectrum (e.g., spectral peak location upon introduction of a new sound) are perceptually enhanced in proportion to the property’s long-term reliability, producing spectral contrast effects (SCEs). For example, a neutral vowel between /ɪ/-/ɛ/ is more likely to be labeled /ɛ/ (high-F1) when preceded by sounds with a reliable low-frequency peak in the F1 range for /ɪ/, and vice versa. Yet, it is unknown how SCEs affect speech perception by hearing-impaired (HI) listeners because research has only examined normal-hearing (NH) listeners. Here, listeners with mild-to-moderate HI identified target vowels varying from /ɪ/-/ɛ/ that followed a precursor sentence. Reliability of precursor spectral peaks was manipulated using low-F1 or high-F1 bandpass filters with + 5 to + 20 dB gain. SCE magnitude was proportional to precursor filter gain (like NH listeners), and surprisingly, to the amount of low-frequency hearing loss. Thus, mechanisms responsible for SCEs are not dependent on healthy hearing, and are magnified by auditory filter broadening associated with sensorineural hearing loss. Implications of these findings for speech perception will be discussed.
“That sounds like me” Infants prefer vowels with infant vocal resonances
Authors: Polka Linda , Masapollo Matthew , Menard Lucie
Published: May 2016

Recent research shows that infants listen preferentially to synthesized vowels that specify an infant source and resonance properties over vowels that simulate a adult female (Masapollo et al., 2015). Infants also preferred vowels with infant resonances over vowels with adult vocal resonances when f0 values were matched (210–240 Hz) across resonance types, suggesting that infant resonance is sufficient to elicit this preference. In this study, we investigate whether infants maintain a preference for infant vocal resonances when f0 values are modulated. In experiment 1, infants listened longer to vowels with infant formants and high f0 values (400–450 Hz) than vowels with adult formants and lower f0 (315–360 Hz). In experiment 2, the same preference emerged when f0 values were reversed; infants listened longer to vowels with infant formants and lower f0 values (315–360 Hz) than to vowels with adult formants and higher f0 (400–450 Hz). These findings show that infant resonance is sufficient to elicit this preference. Given that infants begin to produce vowel-like sounds at 3–4 months, these findings also support the “articulatory filter” hypothesis (Vihman, 1993) which claims that infants are perceptually biased toward speech that resembles their own vocal patterns.
Visual influences on the natural referent vowel bias
Authors: Masapollo Matthew , Polka Linda , Ménard Lucie
Published: May 2016

Research indicates that perceivers (both adult and infant) are universally biased to attend to vowels with extreme articulatory/acoustic properties (peripheral in F1/F2 vowel space). Yet, the nature of this perceptual phenomenon (i.e., the natural referent vowel [NRV] bias) is not fully understood. The present research investigates whether this bias is attributable to general auditory processes or to phonetic processes that track articulatory information available across modalities. In experiment 1, we examined whether adult perceivers are biased to attend to visual information that specifies extreme vocalic articulations. As predicted by the phonetic account, we found a bias favoring relatively more peripheral vowels when only acoustic or only visual speech information was present. In experiment 2, we investigated how the integration of acoustic and visual speech cues influence the effects documented in experiment 1. When acoustic and visual cues were phonetically congruent, a peripheral vowel bias was observed. In contrast, when acoustic and visual cues were phonetically incongruent, this bias was disrupted. Collectively, these results are compatible with the view that the NRV bias is phonetic in nature—the speech processing system appears to be biased toward extreme vocalic gestures, which may be specified in the optic, as well as in the acoustic, signal.
The effect of nearby scatterers on the gain achieved by an acoustic array
Authors: Culver R. Lee
Published: May 2016

The coherent processing of signals from multiple sensors in an array offers improvements in angular resolution and signal-to-noise ratio. When the array is steered in a particular direction, the signals arriving from that direction are added in phase, and any signals arriving from other directions are not. Array gain (AG) is a measure of how much the signal arriving from the steering direction is amplified relative to signals arriving from all other directions. This talk presents measurements along with supporting theory and simulation showing that as scatterer density increases and AG decreases, random phase shifts in individual sensor signals become larger and occur more often, and signal correlation among the sensor is reduced. The theory and numerical simulation linking scatterer density to the AG are in good agreement with the measurements up to the point where multiple scattering becomes important.
Time-space analysis, synthesis, and room response modeling of virtual-reality sound fields using microphone and loudspeaker arrays
Authors: Bai Mingsian R. , Li Yi
Published: May 2016

This paper proposes a unified framework to analyze and synthesize spatial sound fields. In the analysis phase, an unbaffled 24-element circular microphone array (CMA) is utilized to “encode” the sound field based on plane-wave decomposition, whereas in the synthesis phase, a 32-element rectangular loudspeaker array is employed to “decode” the above-encoded sound field based on pressure matching. Plane-wave decomposition can be implemented in two ways. First, a two-stage algorithm uses the minimum variance distortionless response (MVDR) beamformer to estimate the directions of significant plane-wave components. Next, the amplitude coefficients of plane waves are calculated using the Tikhonov regularization (TIKR) algorithm. Alternatively, a one-stage algorithm that treats the sound field as a great number of plane-wave components uniformly distributed at all angles can be used. In this case, either TIKR or convex (CVX) optimization can be utilized to solve the underdetermined problem for a minimum-norm solution or a minimum-cardinality solution. The same technique is also useful in establishing the response model for a reverberation room with all direct sounds and reflections coded into plane-wave components. In the synthesis phase, pressure matching is achieved by the inverse of the preceding room response model for rendering loudspeakers in the reproduction room.
Partially correlated source decomposition techniques from a beamforming analysis
Authors: Harker Blaine M. , Gee Kent L. , Neilsen Tracianne B.
Published: May 2016

Recent improvements have extended the capabilities of beamforming methods from the uncorrelated monopole assumption to enable reconstructions of extended, partially correlated sources. Resulting source information contains both level and coherence properties that can predict the radiated sound field. In addition, the source cross-spectral matrix, while accurate, can in many cases be reduced into a more convenient or physically meaningful set of basis vectors. For example, a wavepacket is a self-coherent distribution that may be used to create a minimal set of mutually orthogonal basis vectors representing the source levels and coherence properties. In this study, a complex, extended, and partially correlated source is modeled, and the simulated near-field measurements are analyzed with inverse techniques (i.e., beamforming). Possible decompositions are evaluated for their ability to accurately represent the source properties, as well as reliably predict the field levels and coherence properties using the fewest basis terms. Decompositions examined include proper-orthogonal decomposition and spatial decomposition based on coherence lengths. The results point towards an improved interpretation of the source reconstructions and methods for predicting the noise environment from an extended, partially correlated noise source. [Work supported by ONR and USAFRL through ORISE.]
Modeling of sub-bottom volume scattering from turbidite sequences
Authors: Olson Derek R. , Holland Charles W.
Published: May 2016

Abyssal sediments near the continental margin are often formed through turbidite deposition, which creates alternating layers of silt and mud. Modeling of reflection and sub-bottom volume scattering from turbidite sequences has been previously studied using an effective medium to model the propagation within the sediment, which is only applicable when the acoustic wavelength is much larger than the average layer thickness in the seafloor, and thus is limited to low frequencies. A volume scattering model is developed here to extend the frequency range of previous models of scattering from turbidite sequences. This model employs the Born approximation, takes into account the correct propagation physics in a layered environment, and uses a point source as an incident field. Model results will be compared to previously reported scattering data collected in the Ionian sea.
How audible tones affect psychoacoustic perception of heating, ventilation, and air conditioning noise
Authors: Lee Joonhee , Wang Lily M.
Published: May 2016

Assessment of noise from heating, ventilation, and air-conditioning (HVAC) equipment using current building noise rating systems like Noise Criteria or Room Criteria is not reliable when the noise signals include audible tones. Equipment manufacturers and the acoustical consulting community have therefore been seeking new tone criteria for HVAC noise. This paper reviews the current knowledge base, regarding perception of tones and development of tone criteria. Two recent subjective investigations by the authors are presented. The first study utilized multidimensional scaling analysis (MDS) to identify key psychoacoustic parameters to predict human responses to HVAC noise. The second study aimed to develop a more precise method to quantify annoyance perception when multiple tones are present. Results have been used to develop an annoyance prediction model for HVAC noise with tones, which may be used to set evidence-based tone criteria.
Predicting airborne sound levels from mechanical equipment rooms
Authors: Doggett Felicia
Published: May 2016

Predicting airborne sound levels from mechanical equipment rooms or rooftop equipment to adjacent occupied spaces has traditionally been a bit of a gray area when it comes to modeling. Over the last two decades, we have attempted to refine our in-house tools to predict sound levels accurately, but there is much information from various sources and it has been difficult to know what is right and what is not so right. The equation NR = TL + 10log(a/S) only applies to reverberant rooms; other equations from Long, Rathe, among others attempt to refine this equation for other conditions including separating out direct and reverberant sound fields. This presentation explores these various modeling techniques and raises the question as to which one may be “most correct” to use for various conditions and situations.