bluuebunny/crossref_metadata_2025 huggingface dataset:
Electroacoustical evaluation of a prototype headphone amplifier for educational purposes
Authors: da Silva Lúcia C. , Brum Ricardo , dos Santos Canabarro Moisés , Paul Stephan
Published: October 2015

In several classroom activities, it is required to feed a signal simultaneously to several headsets to have students listening to the same sound signal, e.g., to show binaural effects. To drive several headphones, an appropriate headphone amplifier is needed. The aim of this work was to build a prototype of a simple headphone amplifier based on a publicly available project around different types of operational amplifiers and test its electrical and acoustical performance when used with typical headphones. Frequency response function, total harmonic distortion, and signal-to-noise ratio were evaluated. Among the different OPAMPs the OPA2134 showed the best performance, especially because of the very flat frequency response function in the hearing range, low harmonic distortion, and superior SNR (−83 dBFS). Acoustical test were therefore performed based on the amplifier with the OPA2134 only, using a Sennheiser HD 600 headphone and a Sennheiser KR4 microphone. THD measured with this configuration ranged from −86 dBC@2.5 kHz and global SPL = 70 dB to −35 dBC@100 Hz and global SPL = 110 dB. At all, the test showed that the amplifier circuit is appropriate for the required application, taking into account that it is very simple and can be mounted easily by the students.
Estimation of the effective perceived noise level during approach of Brazilian AMX A-1 military aircraft
Authors: Murta Bernardo H. , Greco Gil F. , Paul Stephan , Bernardi Jean C. , Pereira Matheus
Published: October 2015

Aircraft noise is an important cause of annoyance mainly in regions close to airports or military airbases. Civil aircraft data of sound emission, such as EPNL, are commonly available to the public; however, for military aircrafts such data are not easily accessible. Noise emission is commonly quantified in terms of Equivalent Perceived Noise Level during approach, low altitude overflight, and simulated take-off. This study presents the results of the estimation of the Equivalent Perceived Noise Level (EPNL) for the AMX-A1 aircraft during approach at Santa Maria's Airbase, in south Brazil. Since there is an University and its Hospital on the surroundings of the airbase, the approach is the most annoying situation. The measurements were made at the vicinities of the airbase based on the equivalent procedures established by ICAO where calibrated wave signals were recorded and processed, leading to results of EPNL of the order of 134 EPNdB. The calculated levels were found to be coherent for military aircrafts and shall be validated with further investigation.
Comparison sound-field measurements of hearing protector attenuation and fit-test systems
Authors: Murphy William J. , Byrne David C.
Published: October 2015

The American National Standards Institute (ANSI), accredited S12 standards committee for noise, working group 11 is developing a standard to characterize the performance of hearing protector fit test systems. An inter-laboratory study was conducted to compare sound field measurements of real-ear attenuation at threshold (REAT) tests of hearing protection with three hearing protection fit-test systems. The draft ANSI standard for personal attenuation ratings from fit-test systems includes adjustments to the fit test system personal attenuation rating for the accuracy and precision of the measurement. As well, adjustments are proposed for the effect of fitting and for spectral variability of effective attenuation. In the inter-laboratory study, two fit-test systems exhibited precision of about 2 dB while the third system had a precision of about 4 dB. The third system underestimated the sound field attenuation by about 2 dB. Because the inter-laboratory study tested two fittings of the hearing protector with each fit-test system, the variability of individual fitting is described as an average of the differences of first and second tests. This paper will also evaluate the effect of the noise spectrum for the three fit-test systems.
The research on piezoelectric cylindrical oscillating transducer for dipole acoustic logging
Authors: Zhou Yinqiu , Wang Xiuming , Dai Yuyu
Published: October 2015

Acoustic transducer, which is a core component of acoustic logging tool, determines the development of acoustic logging technology. In order to realize the goal of dipole acoustic logging transducer with the features of low frequency, broadband and high radiation power, a cylindrical oscillating dipole acoustic transducer using an actuator of a group of different trilaminar piezoelectric bending bars is designed and studied. Modal and harmonic response analyses of the whole transducer are conducted by using the finite element method, including analyses of input conductance of transducer in air and water, transmitting voltage response and directivity patterns. Besides, the proposed transducer is fabricated and tested to compare with numerical simulation results. Moreover, the numerical results of the proposed transducer are compared with that of traditional dipole transducer. The comparison result indicates the proposed dipole transducer is characterized by low frequency, broadband, and high radiation power, which is feasible in the application of dipole acoustic logging.
Induced radiation force and torque on a viscoelastic particle in an ideal fluid
Authors: Leao José P. , Silva Glauber T.
Published: October 2015

The interaction of an acoustic wave with a suspended particle may produce radiation force and torque on the particle through linear and angular momentum transfer. Theoretical analysis of the radiation force exerted on a rigid, compressible fluid, elastic solid, and layered spherical particle is abundantly found in the literature. Nevertheless, less attention has been devoted to cases involving a homogeneous viscoelastic particle, even though viscoelastic materials are ubiquitous. Here, the radiation force and torque exerted on this kind of particle is studied in detail using the fractional Kelvin-Voigt viscoelastic model. Analytical expressions are obtained in the monopole-dipole approximation to a small particle in the long-wave limit. Considering a traveling plane wave interacting with a high-density polyethylene (HDPE) particle, we found that the axial radiation force is negative, i.e., the force and the wave propagation are in opposite directions. For a first-order Bessel vortex beam, a full 3D tractor beam develops on the HDPE particle placed in the beam's axis. Furthermore, negative axial radiation torque also appears on the particle, i.e., the torque and the beam's angular momentum are contrariwise. In addition, possible implications of this method to the advancement of acoustophoretic techniques will be outlined.
A computationally efficient method for the frequency-domain analysis of visco-thermal acoustic propagation in arbitrary geometries
Authors: Martins Gustavo , Cordioli Julio A.
Published: October 2015

The traditional approach used to represent the visco-thermal acoustic propagation within arbitrary geometries is the numerical solution of the full linearized Navier-Stokes (FLNS) equations. The FLNS model, usually solved by means of the Finite Element method (FEM), requires a large number of DOFs to be considered at each node. Therefore, the FLNS becomes much more computationally expensive than the standard acoustic model. An alternative is the sequential linear Navier-Stokes (SLNS) model, which can reduce the computational cost of the solution. However, the SLNS can be still computationally expensive for some types of analysis such as optimization’s procedures. The SLNS model is obtained by means of some simplifications and decoupling of the FLNS equations and requires the solution of a viscous and a thermal dimensionless scalar field. The computational cost of the SLNS approach is manly due to the requirement of the solution of these scalar fields at each discrete frequency. In this paper, a semi-analytical solution of these parameters is proposed and tested in acoustic problems with arbitrary geometries. The new approach shows precision similar to the SLNS model, while the computational cost is only slightly higher than the standard acoustic model.
Objective evaluation of the acoustic properties of various types of chest pieces in the modern acoustic stethoscopes
Authors: Nowak Karolina M. , Nowak Lukasz J.
Published: October 2015

The acoustic properties of a stethoscope are largely determined by the construction of its chest piece, which can either be open or closed with a diaphragm. Different solutions are offered on the market and advertised for their advantages in sound quality. However, no objective data, neither supporting nor disproving the benefits resulting from implementing the specific features, are available. The aim of the present study is to provide such data. A laboratory stand for measuring velocities of vibrations of different points of diaphragms or skin surface during the actual auscultation examination was developed and constructed. Those vibrations are the primary source of the acoustic signal in a stethoscope, and thus, the obtained results provide important conclusions regarding the reasonability of using various types of terminals in chest pieces. It is shown, that thin, stiff diaphragms mounted on susceptible suspension rings ensure significantly better acoustic performance than the other investigated solutions. The influence of the shape and construction of the chest piece on the acoustic properties were evaluated during independent, complementary research, conducted using precision microphone placed in the earpiece of a stethoscope. The obtained results deny the common opinions regarding advantages of the bell-type chest pieces in low-frequency acoustic band.
On material properties and damping models for the dynamic modeling of the human middle ear by means of the Finite Element Method
Authors: Pires Felipe S. , Arellano Diego C. , Paul Stephan , Cordioli Julio A.
Published: October 2015

An accurate dynamic model of the human middle ear is a valuable tool to better understand the mechanisms involved in the human hearing and some middle ear pathologies. It is also essential to the design and evaluation of implantable hearing devices, which may be connected to the middle ear structures. A considerable number of studies describe the development and validation of such models, and a review of these studies shows that there is a significant spread of material and dynamic properties used in the models. In this work, a detailed Finite Element model of the human middle ear, including tympanic membrane, complete ossicular chain, joints, and soft tissues (ligaments and tendons), is constructed and used to assess the influence of the input properties in the middle ear transfer functions. A frequency-dependent acoustic impedance at the oval window is used to represent the cochlea. Ossicle motion predicted by the model is compared with experimental data from the literature, and the effects of different material properties and damping models are investigated. Although variations in material properties can have an impact in the middle ear transfer functions, different damping models shown to have a much larger effect, possibly leading to considerable errors in the numerical predictions.
Phonetically balanced and psychometrically equivalent monosyllabic word lists for word recognition testing in Thai
Authors: Poonyaban Sajeerat , Aungsakulchai Pasinee , Tantibundhit Charturong , Onsuwan Chutamanee , Tiravanitchakul Rattinan , Kosawat Krit , Munthuli Adirek
Published: October 2015

In speech audiometry, a common and crucial method to obtain a suprathreshold (dB) at which words are repeated with maximum accuracy is referred to as word/speech recognition testing. For Thai, Thammasat University and Ramathibodi Hospital Phonetically Balanced Word Lists 2015 (TU-RAMA PB’15) were created with five lists, each with 25 monosyllabic words. Besides its phoneme distributions being based on large-scale Thai spoken corpora [1], TU-RAMA PB’15 is in line with TU PB’14 [2], [3] with emphasis on phonetic balance, symmetrical phoneme occurrence, and word familiarity. To evaluate its homogeneity in terms of decibel intelligibility, the lists were recorded and presented to 10 normal hearing participants, ranging from 0 to 50 dB HL in 2 dB increments (ascending order) until they repeated correct verbal responses. Using logistic regression, regression slopes and intercepts were calculated to estimate percentage of correct performance at any given intensity and to construct psychometric functions for every list. Derived psychometric function slopes ranged from 0.2015 to 0.2262 while intensities required for 50% intelligibility ranged from 17.0876 to 20.8856. Two-way Chi-Square analysis performed on both parameters indicated that there was no significant difference among the five lists. Further testing is needed to verify the use among the hearing-impaired individuals.
Prevalence of acoustic reflexes in the United States
Authors: Flamme Gregory A. , Deiters Kristy K. , Tasko Stephen M. , Ahroon William A.
Published: October 2015

The acoustic reflex is a contraction of the middle ear muscles in response to high-level sounds. Acoustic reflexes are invoked as a protective mechanism in some damage-risk criteria (DRC). However, acoustic reflexes are not always observed among people without auditory dysfunction, and should not be included in DRC unless there is 95% certainty that 95% of the population have acoustic reflexes. In the current study, we present the prevalence of acoustic reflexes among people 12 years and older (N > 11,400), using data from the National Health and Nutrition Examination Survey (NHANES). The NHANES can be used to produce prevalence estimates generalizable to the non-institutionalized U.S. population. Ipsilateral reflexes were screened at two elicitor frequencies and detected using Frequentist methods and via Kalman filtering of the reflex trace. Reflexes are pervasive only among those with hearing thresholds better than 15 dB HL at all frequencies, and fall below the criterion certainty with poorer sensitivity even at lower frequencies. Age and tympanometric variables are also related to reflex detection. Reflex prevalence is generally high among young people with adequate hearing sensitivity for unrestricted military duty, but the prevalence is not uniform among audiometric configurations within this hearing profile.
Acoustic models of co-varying vocal roughness and breathiness
Authors: Skowronski Mark D. , Kopf Lisa M. , Shrivastav Rahul , Eddins David A.
Published: October 2015

Dysphonia is characterized by several vocal qualities including breathiness and roughness. These qualities can coexist within a single voice. To examine the potential interaction between judgments of one voice quality in the presences of another, a large set of synthetic voices that co-varied along the breathiness and roughness continua were created and evaluated by 10 listeners. The perception of roughness (synthesized via amplitude modulation) was unaffected by degree of breathiness. The perception of breathiness, however, was affected by the degree of roughness: for low-breathy voices breathiness increased by about 2 dB as roughness increased from no roughness to maximum roughness; yet for high-breathy voices, breathiness decreased by about 2 dB as roughness increased. Current acoustic models of voice quality (pitch strength, auto-correlation peak, cepstral peak, partial loudness ratio, and glottal-noise-excitation ratio) do not explain the observed interaction of roughness and breathiness. To explain the observed interaction, we evaluate the possibility that roughness perception is dominated by temporal cues (which are unaffected by the presence of breathiness) and that breathiness perception is driven by spectro-temporal cues which are affected by the sub-harmonics generated by amplitude modulation. The sub-harmonics partially contribute to non-harmonic energy (increasing breathiness) and partially mask aperiodic energy (decreasing breathiness).
Motor suppression of the auditory system extends to the brainstem frequency following response and is mediated by attentional demands
Authors: Klos Serena , Nusbaum Howard C.
Published: October 2015

Neural theories of auditory perception often characterize subcortical structures as relay stations by which acoustic input is passively encoded into a representation that can be recognized by cortical networks. However, efferent projections throughout the peripheral auditory pathway (Huffman & Henson, 1990) suggest a corticofugal network consisting of ascending and descending pathways may play an important role in the perception of acoustic signals. Based on cortical suppression evidence in the primary auditory cortex during movement (Schneider et al., 2014), we investigated whether similar suppressive effects can be seen at the level of the auditory brainstem and whether there are interactions with attention. The Frequency Following Response (FFR) to a 440Hz sine tone was measured while participants engaged in two finger tapping tasks equated in motor behavior but varying in attentional demand. Spectral peak analysis of the FFRs revealed decreased amplitude at 440 Hz for the tapping task that required more attention, suggesting that rather than a general suppression of the peripheral auditory pathway during motor behavior, the interaction between the motor system and the auditory brainstem is mediated by attentional networks that are involved in allocating resources to various sensory networks. [This work was supported in part by ONR grant DoD/ONR N00014-12-1-0850.]
The initial head gesture and coordinate system in anthropometric parameters measurement for head-related transfer functions customization
Authors: Yu Guangzheng , He Yingyang , Xie Bosun
Published: October 2015

Head related transfer functions (HRTFs) depend on the sound source position and individualized anthropometry of subject. Accordingly, HRTF measurement usually accompanies with head and pinna-related anthropometric measurement on corresponding subjects. Based on a baseline database of HRTFs and anthropometric parameters, individualized HRTFs of new subject can be customized from anthropometric measurement (Zotkin, et al., 2003). Obviously, the accuracy of anthropometric measurement influences the performance of customized HRTFs. However, the measurement of some pinna-related anthropometric parameters, such as the pinna rotation angel and pinna flare angle, is sensitive to the initial head gesture and coordinate system. In present work, the Frankfurt plane was adopted to initialize the head gesture under the same coordinate system so as to ensure the consistency of anthropometric and HRTF measurement. The suggested method is adopted to measure the head and pinna-related anthropometric parameters of 56 subjects, yielding reasonable and consistent results. [This work was supported by the National Natural Science Foundation of China, Grant No. 11104082.]
Front-and-Overhead Energy Ratio and immersive sound field rendering with height channels
Authors: Kim Sungyoung , Indelicato Mark J.
Published: October 2015

In a discrete channel-based music reproduction, height channels are required to completely manipulate increased immersiveness and enhanced appropriateness for a realistic three-dimensional (3D) sound field. Previous subjective evaluation results showed that the configuration of four height loudspeakers significantly changed perceived immersiveness and appropriateness, and the listeners preferred height-loudspeaker configurations with being “frontal” and “full.” Subsequent analysis failed to determine a prediction model that could account for the variation of the listeners’ perceptual responses using conventional physical parameters including inter-aural difference and coherence. In this paper, the authors proposed a new metric-the ratio between sound energy from front and overhead directions-as a physical parameter for the prediction model. A coincident pair of bidirectional microphones (one facing front and the other facing overhead) measured acoustical impulse responses (IRs) at the listening position for eight configurations of four height channels. Subsequent analysis measured the Front-and-Overhead Energy Ratio (FOER) between two IRs from the eight configurations and found that the ratios were highly correlated with the listeners’ subjective rank data on perceived immersiveness and appropriateness (r = -0.8037). The result implicated that the appropriated configuration of height channels is a critical factor to render a convincing and immersive 3D sound field due to its direct influence on the FOER.
Neural network based speech enhancement applied to cochlear implant coding strategies
Authors: Goehring Tobias , Bolner Federico , Monaghan Jessica J. M. , van Dijk Bas , Wouters Jan , Moonen Marc , Bleeck Stefan
Published: October 2015

Traditionally, algorithms that attempt to significantly improve speech intelligibility in noise for cochlear implant (CI) users have met with limited success, especially in the presence of a fluctuating masker. Motivated by previous intelligibility studies of speech synthesized using the ideal binary mask, we propose a framework that integrates a multi-layer feed-forward artificial neural network (ANN) into CI coding strategies. The algorithm decomposes the noisy input signal into time-frequency units, extracts a set of auditory-inspired features and feeds them to the ANN to produce an estimation of which frequency channels contain more perceptually important information (higher signal-to-noise ratio, (SNR)). This estimate is then used accordingly to suppress the noise and retain the appropriate subset of channels for electrical stimulation, as in traditional N-of-M coding strategies. Speech corrupted by various noise types at different SNRs is processed by the algorithm and re-synthesized with a vocoder. Evaluation has been performed in comparison with the Advanced Combination Encoder (ACE) in terms of classification performance and objective intelligibility measures. Results indicated significant improvement in Hit—False Alarm rates and intelligibility prediction scores, especially in negative SNR conditions. Findings suggested that the use of ANNs could potentially improve speech intelligibility in noise for CI users and motivated subjective listening experiments that will be presented together with the objective results.
Nonlinear ultrasonic waves for structural monitoring: Thermal stress measurement and guided wave management
Authors: Lanza di Scalea Francesco , Nucera Claudio , Sternini Simone
Published: October 2015

This presentation will cover two aspects of ultrasonic nonlinear wave propagation in solids. First, a new model is proposed to justify the existence of wave nonlinearities in constrained solids subjected to thermal excursions. This problem is solved on the basis of the interatomic potential of the solid that indicates a “residual” strain energy, due to the prevented thermal expansion, that is at least cubic as a function of strain. This study finds applications in the monitoring of thermal stresses in buckling-prone structures, such as continuously welded railroad tracks and pipelines. Experimental tests conducted on railroad tracks with realistic support will be also presented. Second, in the case of waveguides the efficiency of nonlinear ultrasonic testing based on higher-harmonic generation strongly relies on the correct identification of favorable combinations of primary and resonant double-harmonic nonlinear wave modes. This presentation will identify these combinations of wave modes in complex waveguides by extending the classical Semi-Analytical Finite Element formulation to the nonlinear regime, and implementing it into a highly flexible commercial Finite Element code. The proposed algorithm is benchmarked for four case-studies, including a railroad track, a viscoelastic plate, a composite quasi-isotropic laminate, and a reinforced concrete slab.
Nonlinear time reversal signal processing techniques applied to acousto-mechanical imaging of complex materials
Authors: Dos Santos Serge , Dvorakova Zuzana , Caliez Michael , Prevorovsky Zdenek
Published: October 2015

Recent ten years have seen considerable development of experimental techniques for improving nonlinear NDT methods and harmonic imaging derived from Nonlinear Elastic Wave Spectroscopy (NEWS). Diagnostic ultrasonic imaging based on higher harmonics yields, among others, a better resolution in view of the decreased wavelength in comparison with the fundamental. Furthermore, using symmetry invariance, nonlinear Time Reversal (TR) and reciprocity properties, the classical NEWS methods are supplemented and improved by new excitations having the intrinsic property of enlarging frequency analysis bandwidth and time domain scales. The purpose of this paper is to present the extension of TR-NEWS for skin aging characterization using the Nonlinear Time Reversal signal processing tool known to localize, in a complex medium, sources of nonlinearity potentially responsible of complex material aging. Linear and nonlinear behavior of skin elasticity is measured locally thanks to an acousto-mechanical loading of the skin conducted with INSTRON loading machines specifically optimized for biomaterials. Hysteresis behavior coming from the complex loading of the skin has been identified with PM-space statistical approach, usually associated to aging process in NDT. Phenomenological hysteretic parameters extracted will be presented and associated to standard parameters used for skin characterization.
Pulse inversion and scaling subtraction signal processing for nonlinearity based defect detection
Authors: Van Den Abeele Koen , Hettler Jan , Tabatabaeipour Morteza , Delrue Steven
Published: October 2015

When seeking out evidence for nonlinear behavior, various signal processing techniques can be applied for the comparison of two signals, one being a slight distortion of the other. For instance, the pulse inversion technique compares the responses to two out-of-phase excitation signals. Alternatively, one can compare the response at a finite (nonlinear) excitation amplitude to a scaled response at a very low (linear) excitation, as performed in the scaling subtraction technique. In this report, several examples are given in which these nonlinearity based signal processing techniques are used in practice to visualize damage features in solids. In view of kissing bond defect detection in friction stir welds, the pulse-inversion method was employed in a contact pitch-catch mode using a chirp signal. B-scan spectral heat maps obtained after pulse inversion allow to easily identify and size damage zones along the weld path. Second, the scale subtraction technique will be illustrated in combination with an ultrasonic sparse array SHM system to detect damage locations (impacts and delaminations in CFRP plates) without the knowledge of baseline signals taken on an intact specimen. Finally, we show that the phenomenon of Local Defect Resonance (LDR) can be facilitated and validated using the scaling subtraction technique.
Soil-plate oscillator: A model for nonlinear acoustic landmine detection
Authors: Korman Murray S. , Sabatier James M.
Published: October 2015

A soil-plate oscillator (SPO) apparatus involves a cylindrical column of granular medium (sand, soil, and pebbles) supported by a thin circular elastic plate (acrylic) that is rigidly clamped to the bottom of a thick walled aluminum tube. The plate is air-backed. The soil column is driven from above by two subwoofers electrically connected to an amplified swept sinusoidal slowly varying chirp. In nonlinear tuning curve experiments, the resonant frequency decreases with increased amplitude—representing a softening in the nonlinear system. Hysteresis effects can be observed along with slow dynamic behavior (associated with mesoscopic nano-scale nonlinear elasticity). In two tone tests, numerous combination frequencies are observed in the surface vibration of the soil along with the sum frequency (typically 200 Hz) and second and higher harmonics. Soil surface vibrations and plate vibrations show similar effects when the soil layer is even 30 times the plate thickness. SPO results compare well when an inert VS 1.6 anti-tank mine is buried in a large concrete soil box. Nonlinear hysteresis models of the soil alone and for the soil-plate interaction are useful in understanding these results, since off-the mine vs. on-the mine tuning curves shapes behave significantly different, indicating some false alarms can be eliminated.
Developmental trajectory for perception of nonnative-accented sentences
Authors: Bent Tessa
Published: October 2015

The ability to recognize words under adverse listening conditions slowly develops throughout childhood. For example, children’s speech perception in noise or reverberation does not reach maturity until adolescence. Much less is known about the developmental trajectory for children’s word recognition under adverse listening conditions stemming from the talker, such as in cases of unfamiliar dialects or accents. To investigate development of word recognition with an unfamiliar accent, 5- to 15-year olds and young adults were presented with native- and Japanese-accented sentences in quiet and noise. Results showed that although 11- to 12-year olds’ word recognition for the native in noise condition was similar to adults, the oldest children in the study (i.e., 14- to 15-year olds) did not demonstrate adult-like word recognition for the nonnative talker, with a large performance gap for the noise-added condition. Therefore, the developmental trajectory for word recognition with unfamiliar accents is quite protracted, similar to word recognition in noisy or reverberant environments. Because children’s performance for the nonnative talker was depressed relative to adults even in quiet, children’s difficulty perceiving unfamiliar accents is likely a consequence of cognitive-linguistic developmental factors or insufficient linguistic experience rather than sensory factors.
Application of random matrix theory to acoustic modeling and signal processing
Authors: Wage Kathleen E.
Published: October 2015

Random matrix theory (RMT) characterizes the eigenvalues and eigenvectors of matrices composed of random entries [Bai/Silverstein, Springer, 2010]. Random matrices play an important role in a variety of acoustics and signal processing applications. For example, mode propagation through internal waves can modeled using random scattering matrices Hegewisch and Tomsovic showed that mode scattering can be analyzed using RMT [JASA, 2013]. In signal processing, the sample covariance matrix is an example of a random matrix that can be analyzed using RMT techniques. RMT differs from classical statistics because it derives results in the limit as both array size and number of measurements approach infinity. This type of asymptotic analysis is crucial because it facilitates the investigation of large dimensional matrices in scenarios with limited numbers of measurements. While results are derived in the infinite limit, many authors have shown that RMT provides useful predictions for finite size matrices derived from finite numbers of measurements. Research in RMT has grown substantially since the 1950s, and new theoretical results are rapidly emerging. This talk reviews several key results from the RMT literature and provides examples to illustrate the analysis of signal processing algorithms and acoustic propagation using these powerful methods.
Project MiMi—Miami-Michigan—The discovery of phase coherent acoustic transmission
Authors: DeFerrari Harry A.
Published: October 2015

Project MIMI aimed to observe the temporal fluctuations of low frequency CW acoustics transmission. At the time, the conventional wisdom was that CW phase was randomized after transmission through the ocean. Experiments (transmission between ships) verified that finding and ray theoretical considerations confirmed that uncertainty in the depth of the upper turning point resulted in large variations in travel time—hence random phase. But, some classified work suggested that the ocean transmission was perhaps stable and coherent. John Stienberg experimental group at Miami installed a 400 Hz. bottom mounted directional source aimed at Bimini, Bahamas, but could barely detect the signal. Ted Birdsall provided signal processing gain (36 dB) with the Phase Coherent Demodulator (PCD) that lead to the discovery of phase coherence. The Miami—Michigan (MiMi) team resulted. John Stienberg found that phase variations had periodicities corresponding to surface wave, internal wave, tide and lunar periodicities. He concluded that by “Oceanographic Acoustics” one could make acoustic measurements of oceanographic variations. Birdsall introduces M-sequences (“Gain of CW with the resolution of a pulse”) to observe pulse arrivals This approach served as a template for dozens of future fixed-system experiments by the basic research community up until the present time.
Bottlenose dolphins direct sonar clicks off-axis of targets to maximize Fisher Information about target bearing
Authors: Kloepper Laura , Liu Yang , Buck John R.
Published: October 2015

Aiming the sonar beam directly at a potential target maximizes the detection information available to an echolocating animal. In contrast, estimating the angular location of a target relies on changes in the received echo spectrum due to the frequency dependence of the transmit beam pattern. The Fisher Information quantifies the available information on angular location in terms of the sensitivity of the received echo spectrum as a function of bearing. We calculated the Fisher Information for a dolphin's echolocation signal and determined the maximum angular location information occurs when the sonar beam is such that the target falls slightly off-axis. To compare the predicted beam aim to the actual beam aim of an echolocating dolphin, we recorded the echolocation signals of a bottlenose dolphin with a 16-element hydrophone array while the animal performed a target detection task. The dolphin consistently pointed its sonar beam 7 degrees away from the target, which is the beam aim that maximizes the Fisher Information for the dolphin signal. [Work supported by NSF and ONR.]
TCAA short course presentation material
Authors: Hoover K. A.
Published: October 2015

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects, called “Architectural Acoustics.” An architect can earn one continuing education unit (CEU) by attending this short course, if it is presented by a qualified member of TCAA. The course covers topics in sound isolation, mechanical system noise control, and finish treatments. This paper will cover the course material in order to prepare and qualify potential presenters. In order to qualify as an authorized presenter for this AIA/CES short course, attendance at this workshop and membership in TCAA are required.
AIA/CES Provider registration and reporting requirements
Authors: Brooks Bennett M.
Published: October 2015

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects. The TCAA short course is called “Architectural Acoustics” and attendance at this one-hour long course can earn an architect one continuing education unit (CEU) with HSW Credit (Health Safety and Welfare). This paper will cover the administrative requirements of the AIA/CES, to prepare potential presenters. These requirements include the proper handling of paperwork, so that AIA members may receive credit for the course. Also, the manner in which the course is given is dictated by AIA requirements. TCAA membership and attendance at this workshop are required to qualify as an authorized presenter for this AIA/CES short course.
In vivo biodistribution of fluorescently tagged magnetic microbubbles for cavitation enhancement with real time passive acoustic mapping
Authors: Crake Calum , Carlisle Robert , Owen Joshua , Smart Sean , Coviello Christian , Coussios Constantin , Stride Eleanor P.
Published: October 2015

Previous work has demonstrated the potential of magnetically functionalized microbubbles to localize and enhance cavitation activity under focused ultrasound exposure in vitro. The aim of this study was investigate magnetic targeting of microbubbles for promotion of cavitation in vivo. Fluorescently labeled magnetic microbubbles were intravenously injected into a murine xenograft model. Cavitation was induced using a 0.5 MHz single element focused transducer at peak negative focal pressures of 0.1–1.0 MPa and monitored in real-time using simultaneous B-mode imaging and passive acoustic mapping. Magnetic targeting was found to increase the amplitude of the cavitation signal as compared with untargeted bubbles and a commercial ultrasound contrast agent. Post exposure magnetic resonance imaging indicated a correlation between cavitation activity and deposition of magnetic nanoparticles in the tumor volume. Magnetic targeting was similarly associated with an increase in the fluorescence intensity measured from the tumors following the experiments; the highest levels corresponding to the maximum cavitation signals. These results indicate a strong correlation between cavitation activity and increased uptake of both molecular species and nanoparticles in tumors; and that the effect can be enhanced by magnetic targeting.
Fast passive cavitation mapping with angular spectrum approach
Authors: Arvanitis Costas , McDannold Nathan , Clement Gregory
Published: October 2015

Several emerging focused ultrasound (FUS) therapies harness the effects produced by acoustic cavitation. Passive acoustic mapping (PAM) can be used to characterize and visualize the microbubble oscillations and guide these procedures. Here, we propose and demonstrate that angular spectrum approach (ASA) can be used to back-project the passively recorded, by an array of receivers, diverging pressure waves generated from oscillating microbubbles to perform rapid PAM reconstructions. In the present work, acoustic cavitation is studied transcranially in non-human primates using an integrated ultrasound and MRI-guided clinical FUS system. In addition, from CT datasets, we also extract the skull acoustic properties and use them as inputs to numerical simulations. Using both the simulated and experimental data we validate the use of ASA to perform PAM reconstructions and compare its performance to time domain PAM. The experimental data demonstrate that ASA can be used to reconstruct frequency-selective PAM. Numerical simulations suggest that ASA reconstructions have the same resolution with time domain PAM, while the reconstruction time was 72 times faster for the same image dimensions. These results suggest that ASA-based PAM reconstructions can provide real-time passive cavitation mapping and, by extension, control over FUS procedures.
Propagation of acoustic education in space and time
Authors: Kim Yang-Hann
Published: October 2015

Sound is every where and any time. Human is always surrounded by sound. However, understanding sound is not always available to everyone. It's concepts start to be introduced from elementary school to college, but implementing sound for his/her purpose is always problematic. One reason why sound is so difficult to understand is because it is not visible. There have bee numerous attempts to make sound visible: using water, many candle lights, string, small particles, and many microphones. Another hurdle that we have to go over to really enjoy and use sound is to have a convenient tool for manipulating sound. However making one's own speaker cannot be tackled by using a home took box. However, we are about to make this dream come true: many good speakers can be found in relatively cheap price and tangible manipulation tools begin to be available. This paper introduce how these tools have been developed and can be used for education. Another issue associated with learning sound is how to make acoustic education available to anyone and anytime: distance education, using Internet can be a solution. Past experience will be introduced: college lecture, short course for industry, Internet lecture, and finally MOOC lecture for acoustics are compared. What their characteristics are, and how to use them are to be discussed.
Hot topics in underwater acoustics: Recent advances in underwater unexploded ordnance classification
Authors: Espana Aubrey L. , Williams Kevin L. , Kargl Steven G.
Published: October 2015

For decades, broadband sonar has been a key tool in the underwater detection and classification of man-made targets. The DoD’s recent focus to clean up discarded WWII-era munitions has pushed a flurry of research and advancements in the areas of target scattering, environmental noise modeling, signal processing, and automatic target recognition (ATR). It is the interdisciplinary nature of this problem that makes it incredibly challenging, namely, the fact that the ability to classify an object is heavily influenced by the operational choices (grazing angle and vehicle altitude), surrounding environmental factors (target type, burial state, sea state, and bottom topography), and the processing tools (data products, feature-set, and ATR training/testing). This talk will outline the key steps underlying the process of trying to detect and classify underwater unexploded ordnance (UXO). It begins by pushing raw time domain data, which can be generated either experimentally or via models, through a set of signal processing tools to create data products (acoustic color and SAS images). These data products are fed through feature extraction processes, followed by ATR algorithms, in order to arrive at the final classification of an object. Examples to be presented include objects of interest to the remediation of underwater UXO. [Research supported by SERDP and ONR.].
Are phonetic contrasts enhanced in clear speaking styles?
Authors: Tuomainen Outi , Hazan Valerie
Published: October 2015

When asked to speak clearly, talkers make adaptations to various acoustic characteristics of their speech. Do these adaptations specifically enhance phonetic contrasts or just result in more global enhancements? For phonetic contrasts, increased discriminability could be achieved by increasing between-category distance, reducing within-category dispersion or both. The LUCID corpus contains 32 iterations per consonant for each of 40 adults for the /s/-/∫/ and /p/-/b/ contrasts. Iterations were obtained via picture elicitation in a sentence context in two conditions: when asked to speak casually and clearly. Friction centroids were measured for /s/-/∫/ and voice onset times for /p/-/b/. For /s/-/∫/, although there was significantly greater distance between centroids in the clear speech condition, within-category dispersion did not differ across speaking styles and there was no significant increase in overall discriminability in the clear condition. For /p/-/b/, in the clear condition, there was a significant increase in VOT distance, a significant decrease in within-category dispersion, resulting in an overall increase in discriminability. These results show that clear speaking styles can lead not only to global enhancements to speaking rate, intensity, pitch characteristics but also to increases in discriminability at the segmental level, although this may be contrast-specific.
Contributions to acoustical comfort in the built environment, 1956–2015
Authors: Christoff Jerry , Good Jim , LoVerde John , Dong David W. , Rawlings Samantha
Published: October 2015

When the senior author joined Paul S. Veneklasen & Associates in 1956, research was under way on speech intelligibility relative to background noise, not in buildings but in spacecraft! Back on earth, additional studies countered the then-popular idea that gypsum board construction was low quality with poor sound isolation, leading to the development of multi-layer gypsum board wall designs for office buildings and studios. Further investigations predicted speech intelligibility based on design features and led to development of prototype masking noise systems. A set of acoustical design elements (such as tall furniture barriers, sound-absorptive barriers and ceilings, and orienting workstations to maximize distance) emerged naturally from these studies. Within the last couple of decades, however, open-plan office design has evolved away from traditional design, incorporating fewer of these design elements. This provides opportunity to evaluate the efficacy of standard design elements in modern collaborative work areas. Occupancy surveys and acoustical measurements were performed in open office areas of six companies. The results verify the effectiveness of traditional acoustical design elements, but also indicate where typical acoustical design practices may be modified while maintaining acceptable acoustical performance in collaborative open office areas.
Capturing office acoustics in the design and construction process
Authors: Wowk Roman , Papadimos Chris
Published: October 2015

Given the realities of the design and construction process, basic qualities for office acoustics including speech privacy, freedom from distraction and speech intelligibility are often compromised or neglected altogether. A scan of recent news articles not only yields numerous accounts of poor conditions, but several academic studies have also shown how poorly acoustics compares with other indoor environmental qualities. This cannot be overlooked as a factor affecting productivity and performance. While the marketplace has no shortage of potential solutions for office acoustics, no product or design upgrade alone is a substitute for good design and planning, regardless of its role in previous solutions. Several essential but independent elements must be considered together for successful and cost-effective outcomes. This necessitates an integrated approach with consensus between user expectations and any design limitations, early consideration of acoustics during space planning, and the right balance of upgrades to meet project criteria. However, even basic oversights during construction can unravel even a wholesome design without coordination between trades, verification of acoustic performance, and field review. This presentation will show through case studies how such a process has either been successfully executed or systematically neglected and how that has affected the outcome on various projects.
Research methods to investigate the effects of acoustics on occupant comfort and productivity in the built environment
Authors: Vigeant Michelle C. , Bahnfleth William P.
Published: October 2015

A number of factors affect building indoor environmental quality (IEQ), principally thermal environment (temperature, humidity, and air movement), indoor air quality (IAQ), lighting, and acoustics. Most studies on comfort or preference and virtually all dealing with health and productivity focus on thermal environment and IAQ. However, a recent meta-analysis showed that thermal comfort ranks only slightly higher in importance than acoustic comfort and IAQ (Frontczak & Wargocki 2011). Although not focused on acoustics, these prior studies do provide insight into appropriate methodologies. Perceived IEQ is the most widely studied since it is relatively simple to measure and can be compared to perception-based acceptability criteria. Some investigations go beyond formal surveys by including quantitative measures, such as overall productivity, student learning, and health. These data can be used for monetization of benefits and cost, where the typical finding in studies focused on the thermal environment and IAQ is as high as 10:1. Overall, the field of IEQ needs to move from perceived quality metrics to performance metrics, but more work is needed to establish sufficiently accurate quantitative measures. These advances will be especially beneficial to building occupants by providing better working environments both in terms of health and productivity.