bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of sound transmission through mud at Dodge Pond, Connecticut.
Authors: Carey William M. , Pierce Allan D.
Published: October 2009

Questions important to the sonic detection of buried ordinance are whether the sound dispersion and attenuation of muddy bottoms can be predicted and verified. Wood and Weston [Acustica (1964)] measured compressional speeds in harbor mud 3% less than that of water with attenuation considerably less than those of sandy/silty sediments. A recent theoretical treatment [Pierce and Carey, POMA, 7001 (2009)], making use of the Mallock–Wood equation and of a card-house theory of the structure of mud, estimates the slow sound speed to depend on porosity as 1−(0.35)(1−φ). Present measurements at frequencies between 1 and 10 kHz with a buried array in the depositional mud at the bottom of Dodge Pond, which contains considerable gas microbubbles, yield speeds of the order of 60% of the sound speed in water. The initial measurements on the disturbed sediment were found to be strongly influenced by scattering from larger bubbles whereas the results after a period of 10 months showed the effect of a smaller size distribution of bubbles. Estimates based on the Dodge Pond measurements and on the card-house theory of the propagation characteristics and of the effect of micro-bubbles are discussed. [Sponsored by SERDP-NSWC-PCD.]
The role of porosity fluctuations in scattering from sand sediments and in propagation losses within the sediment.
Authors: Hefner Brian T. , Jackson Darrell R.
Published: October 2009

Acoustic backscattering from a diver-smoothed sand sediment was measured at frequencies from 200 to 500 kHz as a function of grazing angle. The residual roughness of this smoothed surface was measured using a laser line scanning system capable of measuring sub-millimeter heights over a 4-meter track. Using the measured sediment roughness, perturbation theory underestimates the scattering strength at all frequencies for angles greater than the critical grazing angle. The absence of large, discrete scatterers in the sediment suggests that scattering from fluctuations in the sediment properties may be the dominant scattering mechanism for these angles. The sound speed and attenuation were also measured in this sediment and the attenuation was found to exhibit a linear frequency dependence similar to that observed for other sand sediments. To account for this linear attenuation, a theory that incorporated scattering losses due to porosity fluctuations into the effective density fluid model has been developed. This theory suggests that the propagation losses may be connected by the same physical mechanism to the scattering of sound from the sediment. This connection is explored in the context of these scattering and propagation measurements.
Measurements of sound speed, attenuation, and normal-incidence reflection coefficient in water-saturated glass beads as a function of porosity.
Authors: Argo Theodore F. , Guild Matthew D. , Wilson Preston S. , Schröter Matthias , Radin Charles , Suntrup Donald J. , Swinney Harry L.
Published: October 2009

Sound propagation in water-saturated granular sediments is known to depend on the sediment porosity, but few data in the literature address both its frequency and porosity dependency. To address this deficiency, a method to control porosity [Argo et al. J. Acoust. Soc. Am. 124, 2469 (2008)] was used to prepare artificial sediments composed of water-saturated glass spheres (130, 265, and 530 μm diameters) with porosities ranging from 0.37 to 0.43. Through-transmission measurements were performed for frequencies from 250 to 800 kHz to determine the sound speed and attenuation. Pulse-echo measurements for frequencies from 0.25 to 7.5 MHz were performed to determine the normal-incidence reflection coefficient. For both classes of measurements, the Fourier phase technique was used to analyze the data. Measurement results will be presented and compared to existing models. A Biot-based model was found to qualitatively describe the porosity dependence of the sound speed and attenuation, but a transition to a scattering-dominated regime was observed. [Work supported by NSF, ONR, and the Welch Foundation.]
Hemi-anechoic chamber source considerations for chamber qualification in compliance with ISO 3745:2003(E).
Authors: Winker Douglas F.
Published: October 2009

Source directivity specifications for qualifying the inverse square law performance are given in ISO 3745:2003(E) Annex A.2.2.2. These specifications are difficult to meet, especially for a single source. Multiple sources are required to qualify a chamber across its usable range. Sources used at low frequencies are relatively simple to design. As frequency increases, compliance becomes increasingly difficult. The design parameters will be discussed, and the advantages and disadvantages of several sources will be discussed. Both commercially available and new designs were tested in accordance with A.2.2.2 with varying results. The frequency ranges of source qualification will be evaluated as well as their impact on the chamber traversing process. Source directivity patterns will be presented and compared to A.2.2.2. Deviations from A.2.2.2 will be examined, and the reasons for these deviations will be evaluated.
Room requirements for laboratory measurement of transmission loss and impact sound insulation.
Authors: Gover Bradford N. , Nightingale Trevor R. T.
Published: October 2009

Laboratory measurement of transmission loss (ASTM E90) and impact sound insulation (ASTM E492) have one thing in common: measurement of the sound power radiated into the receive room by the specimen under test. In E90 the reported quantity, transmission loss (TL), is the difference between the incident and transmitted sound power, whereas for E492 the reported quantity, normalized impact sound pressure level (NISPL), is a direct measure of the radiated sound power of the floor. A derivation of the TL and NISPL equations using a statistical energy analysis (SEA) framework shows that the ASTM equations are based on the assumption of power balance and statistical sampling of the sound field. This SEA framework is used to define the acoustical conditions of the receive room (number of modes in each frequency band, the average loss factor in each band, and hence the modal overlap factor), which are then related to the physical properties such as room shape, volume, absorption, etc. The conditions necessary for meaningful measurements in SEA are compared to ASTM and ISO requirements for receive rooms. A recommendation for possible revisions to enhance test method consistency and accuracy is discussed.
Uncertainty of sound power levels determined following Air Conditioning Heating and Refrigeration Institute Standard 220.
Authors: Lind Stephen J.
Published: October 2009

As part of the AHRI, ASA-ANSI, and ISO standard development processes, the uncertainty of sound power measurements needs to be quantified for inclusion in sound power standards. A study of three reverberation rooms with volumes of 140, 280, and 560 cm3 was undertaken. Sound power levels for two noise sources (a horizontal shafted reference sound source and a leaf blower) were determined using ARI Standard 220. Variables investigated include source location, source orientation, room conditions, source operating characteristics, and microphone traverse length. The frequency range of interest was 25 Hz–10 kHz. Measurements were repeated and the order of tests was randomized. Of particular interest was the difference between the 140-ft3 room and the other rooms to confirm the room qualification process required by ARI Standard 220 because the 140-ft3 room does not meet the ARI Standard 220 qualification process but does meet the requirements in ISO 3741. This work will be helpful in understanding the sources of variation and allow for a starting point for determining if improvements are needed and if so what factors should be considered.
A proposal for systematic investigation of reproducibility deviations in Laboratory Acoustical Measurements.
Authors: LoVerde John , Dong Wayland
Published: October 2009

Cases have been observed in airborne sound isolation and impact noise insulation testing where apparently identical assemblies have achieved significantly different STC and/or IIC ratings, not only when tested at different test facilities but also when re-tested in the same facility [J. LoVerde and W. Dong, J. Acoust. Soc. Am. 125, 2629 (2009); J. Acoust. Soc. Am. 123, 3504 (2008)]. Acoustical test data will be presented demonstrating several cases and showing that the deviations are significantly larger than the expected statistical variation based on the reproducibility of the test method as reported within the applicable ASTM standards. The reason(s) for the variation in these test results are unknown, and there has been no systematic investigation of possible causes. Standards committees, test laboratories, and government agencies have not shown a satisfactory level of interest in either quantifying the deviations or exploring the reasons behind them, which may be theoretical, material, and/or procedural. A protocol is presented for a se-ries of investigations that could be performed in an acoustical testing laboratory intended to identify and quantify causes of the variations.
Comparison of fluctuations of a broad-band pulsed acoustic signal in the Philippine Sea to simulation.
Authors: White Andrew W. , Henyey Frank S. , Andrew Rex K. , Mercer James A. , Worcester Peter F. , Dzieciuch Matthew A.
Published: October 2009

The North Pacific Acoustic Laboratory (NPAL) has conducted several long-range (>500-km) experiments in the North Eastern and North Central Pacific Ocean. In April 2009, NPAL conducted an engineering test/pilot study in the more oceanographically energetic Philippine Sea in preparation for a longer-duration experiment in 2010. Transmissions from a ship-suspended source were to be recorded on a vertical line array at a comparatively shorter range of ≈100 km. Statistics of fluctuations of the acoustic field are found by simulated broad-band signal propagation through a model of the Philippine Sea environment. Model parameters are chosen following analysis of environmental data taken during the engineering test. Simulation-based predictions are compared to experimental data and to predictions of acoustic fluctuations in the less-energetic North Eastern and North Central Pacific Ocean. [Support for this work was provided by the Office of Naval Research.]
Effect of random hydrodynamic inhomogeneities on low-frequency sound propagation loss in shallow water.
Authors: Lunkov Andrey A. , Petnikov Valeriy G.
Published: October 2009

Low-frequency (100–500 Hz) sound propagation loss on the US Atlantic continental shelf and in the Barents Sea in the presence of stochastic surface waves, and for the US Atlantic shelf also in the presence of internal waves, is studied for the range of up to 150 km by means of numerical simulations. Surface waves simulations are carried out with Pierson–Neumann spectrum. Internal wave field realizations are modeled according to frequency spectrum of thermocline displacements that were recorded in Shallow Water’06 experiment. Qualitative difference between sound propagation loss behavior on the US Atlantic shelf and in the Barents Sea is demonstrated for summertime conditions even without random inhomogeneities. It is shown that whereas internal waves, on average, have a weak effect on propagation loss, surface waves result in its considerable increase in both areas under wintertime conditions with a wind speed of more than 9 m/s. [The authors wish to acknowledge and thank Dr. J. F. Lynch for discussing this work. The work was supported by the Russian Foundation for Basic Research Project 08-02-00283 and by the Civilian Research and Development Foundation Project No. REC 010.]
Amplitude and phase front variations for individual modes in Shallow Water 2006 Experiment.
Authors: Badiey Mohsen , Katsnelson Boris , Malikhin Andrey , Lynch James
Published: October 2009

Using modal selection techniques, developed for an L-shaped array, the amplitude and phase front variations for individual modes are considered for shallow water waveguides in the presence of internal waves (IWs). Experimental data collected during the Shallow Water 2006 Experiment include acoustic transmissions during several IW events. In this paper, we focus on one of these IW episodes (i.e., event 50) where a train of nonlinear IW was moving approximately across an acoustic track. Low-frequency LFM signals with band 270–330 Hz were transmitted from a source moving with the advancing IW front and were received by an L-shaped array for few hours. During this time, the angle between the acoustic track and the IW front changed while transmissions continued. The waveguide in the presence and the absence of a train of IW was observed providing excellent environmental input for modeling. Fluctuations of the intensity as well as the modal phase are studied using experimental data and modeling of the waveguide during this period. [Work supported by ONR321OA and CRDF].
Efficient high-frequency underwater acoustic propagation through random media with wavefront predistortion by singular value decomposition: a communication perspective.
Authors: Burton Lisa J. , Puryear Andrew , Lermusiaux Pierre F. J.
Published: October 2009

Acoustic propagation through the fluctuating ocean environment severely limits the capacity of existing underwater communication systems. Specifically, surface waves, small scale turbulence, and fluctuations of physical properties generate random signal variation that creates deep fades and limits reliable communication to low data rates. This paper presents new theoretical signal processing techniques that use channel state information to provide high-rate reliable communication. Specifically, a general framework for efficient propagation through the ocean random media is presented, where efficiency is defined in terms of minimizing bit error rate. Based on results from this propagation framework, a communication architecture that optimally predistorts the acoustic wave via spatial modulation by singular value decomposition and detects the acoustic wave with optimal spatial recombination to maximize reliable information throughput is presented. This effectively allows the system to allocate its power to the most efficient propagation modes while mitigating intersymbol interference. The system consists of a plane of transmit apertures (acoustic emitters) and a plane of receive apertures (hydrophones). This method is applicable to link ranges of 100–1000 m using frequencies between 10 and 30 kHz. Many emerging applications, including real-time ocean observation systems, have the potential to benefit from the proposed architecture. [Support from NSF-GRFP and ONR.]
Inertial cavitation thresholds during standing wave disruption using random phase modulation.
Authors: Farny Caleb H. , Tang Sai Chun , Clement Greg T.
Published: October 2009

In low-frequency transcranial ultrasound therapeutic applications, such as sonothrombolysis, standing waves have been identified as a potential source of undesirable collateral damage due to cavitation. Recently, a method for disrupting the standing wave pattern was developed by modulating the phase of the driving signal, producing a beam pattern with significantly lower ripple in pressure along the acoustic axis. Here we present a study conducted to determine the inertial cavitation threshold in tissue-mimicking phantoms placed in a standing-wave-inducing chamber when the 272-kHz focused therapy transducer was excited separately by a monochromatic or phase-modulated continuous-wave signal. A 10-MHz receiver was used as a passive cavitation detector whose signal was digitally sampled to examine changes in the broadband signal amplitude. Results indicate that the pressure threshold for inertial cavitation is higher during random phase modulation, suggesting that such an approach would be suitable for transcranial ultrasound therapy. These results agree with a simulation of similar excitation signals on the bubble dynamics, which suggest that disruption of timing on bubble forcing reduces the explosive growth required to induce inertial cavitation. [Work supported by NIH Awards R25 CA089017-06A2 and U41 RR19703.]
Determination of ultrasound contrast agent shell rupture thresholds using double passive cavitation detection.
Authors: King Daniel A. , Roberts Alayna C. , Malloy Michael J. , Haak Alexandar , Yoder Christian C. , O’Brien William D.
Published: October 2009

Double passive cavitation detection involves the confocal alignment of one transmit and two passive receive transducers. Highly dilute mixtures of ultrasound contrast agents (UCAs), including Definity, Optison, and non-commercial microbubbles, were prepared such that on average only a single UCA was present at the confocal region. A 3-cycle incident pulse repeating at 10 Hz was varied in frequency from 0.9 to 7.1 MHz and in peak rarefactional pressure (PRP) from 200 kPa to 6 MPa. The acquired signals were classified according to the presence or absence of a postexcitation signal (PES), a quantifiable aspect of the acquired temporal signal which is hypothesized to occur due to the rupture of the UCA shell and therefore indicate the collapse of the microbubble. The resulting percentages of UCAs with PES were fitted with modified logistic regression curves to determine percentage collapse thresholds. The percentage of signals exhibiting PES was found to increase as frequency decreased or as PRP increased while holding other acoustic parameters constant, in agreement with alternative methods of measuring collapse. Definity was found to have a lower threshold of collapse than Optison, while the thresholds of the non-commercial UCAs depended on their physical properties. (Work supported by NIH Grant No. R37EB002641.)
An in vitro study of the relationship between the size of lipid-coated microbubbles and frequency-dependent attenuation coefficient.
Authors: Gong Yanjun , Cabodi Mario , Porter Tyrone M.
Published: October 2009

Monodisperse populations of lipid-coated microbubbles were produced using a flow-focusing microfluidic device. The microbubbles were formed by forcing a lipid solution and perfluorocarbon gas through a narrow orifice simultaneously. The average bubble size depended on the lipid solution flow rate, the gas pressure, and the size of the inlet microchannels and narrow orifice. We have successfully produced monodispersions of microbubbles with average diameters ranging from 4–11 μm. Monodisperse bubble populations were suspended in an exposure vessel, and the attenuation coefficient between 1–7.5 MHz was measured using an acoustic spectroscopy method. The frequency at which the peak attenuation coefficient was measured was dependent on the mean bubble diameter. For example, microbubbles with diameters of 4 and 8 μm had peak attenuation coefficients at approximately 3.0 and 1.5 MHz, respectively. Additionally, it was noted that the bandwidth of the frequency-dependent attenuation coefficients was wider for polydisperse populations compared to monodisperse populations of lipid-coated microbubbles. Implications of these results on the acoustic characterization and use of monodispersions of lipid-coated microbubbles for molecular imaging will be discussed.
Quantitative measurements of microbubble interactions with surrounding vessels and tissues.
Authors: Chen Hong , Kreider Wayne , Kucewicz John C. , Bailey Michael R. , Brayman Andrew A. , Matula Thomas J.
Published: October 2009

Understanding the coupled interactions between acoustically activated microbubbles and surrounding tissues is important for both diagnostic and therapeutic applications. However, little is known about ultrasound-induced coupled interactions between microbubbles and blood vessels. In this work, high-speed microscopy was used to investigate the coupled interactions inside vessels of ex vivo rat mesentery. A 1-MHz focused ultrasound transducer was used to transmit a single pulse to tissue samples having blood vessel diameters of 10–100 μm. Bubble-tissue interactions were captured with a high-speed camera and an inverted microscope. For pressure amplitudes ranging from 1 to 7 MPa, several phenomena were observed: (a) microbubble oscillations caused localized dilation and invagination of the vessels, (b) microbubble jetting occurred where most jets were directed away from the adjacent vessel wall, and (c) connective tissue surrounding the vessels moved with the vessels. The talk will focus on quantitative measurements of vessel motion, strain, and jet velocities. [Work supported by NIH Grants 5R01EB000350, 5R01AR053652, 5P01DK043881, and DK070618.]
A model for the dynamics of ultrasound contrast agents in soft tissue.
Authors: Qin Shengping , Ferrara Katherine
Published: October 2009

For a bubble suspended in an incompressible and infinite liquid, the dynamics of a clean gas bubble can be described by the Rayleigh–Plesset (RP) equation. The RP equation has been applied to approximately simulate the behavior of ultrasound contrast agents (UCAs) in blood, and extended RP equations have been proposed to account for the effects of the UCA shell and surrounding soft tissue. These models produce consistent results with experimental measurements for low acoustic pressure scenarios. For applications of UCAs in therapeutic medicine, the transmitted acoustic pulse can have a peak negative pressure up to a few megapascals, resulting in violent oscillations of UCAs and discrepancies between measurements and predictions using these extended RP equations. Based on the Keller equation, we developed a new model to describe the dynamics of UCAs in the body while taking account of liquid compressibility and shell and soft tissue effects. Liquid compressibility is approximated to the first order, and the shell is treated either as a layer of visco-elastic solid or a viscous liquid. Finite deformation of the shell is included. Typical UCAs with a lipid or albumin shell are investigated, and the effects of soft tissue and blood are examined.
Optimal control point distributions for waveform diversity.
Authors: McGough Robert J. , Jennings Matthew R. , Zeng Xiaozheng
Published: October 2009

Waveform diversity is a method for tumor heating with ultrasound phased arrays that extend the concept of multiple focusing to achieve an optimal sequence of power depositions. Waveform diversity minimizes the power deposited at control points in normal tissue while maximizing the power at control points in the tumor through an approach that employs semi-definite programming. As with other spot scanning and multiple focusing techniques, the performance of waveform diversity depends on the location of the control points. For example, single spot scanning is limited by intervening tissue heating, so the ideal spot scanning approach in large tumors focuses on the back half of the tumor and allows intervening tissue heating to fill in the remaining tumor region. In contrast, waveform diversity combined with mode scanning tends to preferentially deliver heat beyond control points placed in the tumor. In an effort to exploit this feature, the energy delivered to control points on the front face of the tumor is maximized, and the energy delivered to control points along the tumor axis and directly behind the tumor is minimized. Results show that this control point distribution applied to waveform diversity combined with mode scanning achieves conformal heating in a 3-cm-diameter spherical tumor model that is heated by a 1444 element spherical section array.
Estimation of mechanical properties of tissue using laser-induced microbubble interrogated by acoustic radiation force.
Authors: Yoon Sangpil , Aglyamov Salavat R. , Karpiouk Andrei B. , Emelianov Stanislav Y.
Published: October 2009

Measurements of mechanical properties of tissue can be used in many applications ranging from disease diagnosis to treatment planning and monitoring. In this paper, we present a technique to measure mechanical properties of the tissue undergoing laser surgery during which the cavitation bubble is introduced. Utilizing the laser-induced microbubble, the mechanical properties of the tissue were assessed by measuring displacement and oscillations of the bubble under applied acoustic radiation force. The bubbles were produced using a nanosecond pulsed laser operating at 532 nm. Using the lens (0.92 numerical aperture, 11.5-mm focal length), the laser beam was focused inside the gelatin to create microbubbles ranging from 80- to 250-cm diameter. The bubbles were then interrogated using acoustic pulses of different durations and amplitudes. First, the size of each laser-induced microbubble was estimated by measuring the laser-produced shock wave and pulse-echo ultrasound signals. Then, a 1.5-MHz transducer generated an acoustic radiation force to displace the microbubble while a 25-MHz transducer probed the microbubble continuously to measure the resulting displacement. Finally, using theoretical model, viscoelastic properties of the medium were assessed from the measurements of the bubble dynamic behavior. The results were verified using optical methods.
Drumhead resonances in circular elastic membranes.
Authors: Gladden Joseph R.
Published: October 2009

A classic problem in continuum mechanics is determining the normal modes of vibration of a thin elastic membrane with a circular geometry that is clamped at the edges. The analytical solution to the displacement field of such a problem are Bessel functions of the first kind. In this talk, I will describe the construction of a drumhead apparatus consisting of a latex sheet with a circular geometry in which the tension can be varied. Normal modes can be excited using a simple speaker and a strobe light can be used to slow the motion allowing close inspection of the displacement field. The various modes can then be compared to analytical solutions. The shift in natural frequencies of the system due to changing boundary conditions can be demonstrated by placing a hand close to the vibrating membrane.
Why we have two ears-take two: A revised experiment on sound localization.
Authors: Muehleisen Ralph T.
Published: October 2009

Whether they fly, swim, crawl, or walk, vertebrates have binaural auditory systems. Two ears provide redundancy in case of injury to the auditory system, improve the ability to detect quiet sounds, and perhaps most importantly, improve the ability to localize sound. A simple experiment in sound localization using headphone based auralization was presented at a previous meeting. In response to some very useful suggestions a new experiment has been developed. In this experiment, a subject sits in a swivel chair and a sound source is placed a distance away. The subject is rotated a random amount in the swivel chair. The tester then plays the test signal and the subject indicates the perceived direction of the sound. The experiment is repeated with one ear plugged using a high isolation insert earplug. The tests are performed with two types of sounds; a transient noise source with high-frequency tones and/or broadband components such as bird call and source that is primarily low-frequency tones such as a fog horn. The experiments are best performed in quiet rooms with few reflections.
Alvin Lucier’s method for determining the acoustic modes of a room.
Authors: Piacsek Andrew
Published: October 2009

Students can learn about standing waves in rooms as they recreate the classic 1970 recording by Lucier, “I Am Sitting in a Room”. In this work, the composer records himself describing the process in which he is engaged. The approximately 1-min recording of his speech is then played back and re-recorded in the same acoustic environment (an unspecified room). The recording and playback process is repeated several times; the complete work consists of a sequential playback of each iteration. From an acoustically unremarkable, if slightly reverberant, initial recording, the speech is altered with each iteration as the resonance frequencies of the room are amplified relative to other frequencies. Eventually, intelligibility is lost and all that is heard are the modulated tones comprising the harmonic series. Using only a microphone, a digital recording device, a playback system, and a suitable room, students can reproduce this effect while investigating how the room dimensions, shape, and wall materials affect the final outcome.
Updated American Society of Heating, Refrigerating and Air-Conditioning Engineers Guidelines and Standards on Sustainable Systems Design.
Authors: Ryherd Erica E. , Lawrence Tom
Published: October 2009

Many designers look for guidance with the various standards targeting sustainable, green buildings. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) publishes a number of useful design resources related to green buildings. The resources are widely used among mechanical systems engineers and facilities designers. This talk will present an overview of several ASHRAE resources which include acoustics aspects. “ASHRAE Green Guide: The Design, Construction and Operation of Sustainable Buildings” is a book to teach designers how to effectively participate on green building design teams and fundamental green design concepts. The book takes an integrated building systems perspective by addressing how engineered systems interact with and are influenced by architectural design. It also includes guidance on the U.S. Green Building Council’s LEED® rating system. ASHRAE is also in the final stages of preparing a new Standard for High-Performance Green Buildings (Standard 189.1). This Standard is co-sponsored by the U.S. Green Building Council. Standard 189.1 is being written as an ANSI-level Standard and intended for adoption into state and local building codes.
Washington State’s Sustainable Schools Protocol.
Authors: Bruck Daniel C. , Hesedahl Jeanette
Published: October 2009

With the High-Performance Public Buildings Act signed into law in 2005, Washington State developed the Washington Sustainable Schools Protocol as a goal-setting and planning tool for school districts to clearly communicate design goals and meet requirements for state-funded building projects. Based on the Collaborative for High Performance Schools Criteria and similar to the US Green Building Council’s Leadership in Energy and Environmental Design rating system, the Washington Sustainable Schools Protocol system requires school facility projects to achieve a minimum level of points in the categories related to site, water, materials, energy, indoor environmental quality, and innovation. A minimum acoustic performance level for classrooms and other learning spaces is the prerequisite to achieving up to three additional points with improved acoustic performance and audio enhancement. Although clearly a compromise, the acoustics related requirements and optional credits within the Washington Sustainable Schools Protocol has set the starting point for supporting acoustically effective speech communication and learning environments for publicly funded schools in the State of Washington. This paper summarizes the development of the Washington Sustainable Schools Protocol, current acoustical related credits, and lessons learned that may be useful for other jurisdictions considering the development of their own standards.
Integrating acoustical issues in the design of “green” schools.
Authors: Siebein Gary W. , Jones Chris , Lilkendey Robert M. , Paek Hyun
Published: October 2009

ANSI 12.60 and LEED for schools are relatively explicit about the acoustical requirements needed to meet each standard. In practice, many schools are built that develop in an uneasy way trying to meet LEED criteria because a method to integrate acoustical design principles with the basic architectural design scheme of a school has not been assimilated into the professions. This paper presents a core set of acoustical planning principles that can be implemented early in the design process so that LEED and ANSI criteria for room finishes, sound isolation, and building equipment noise can be met as the design progresses.
Acoustic performance measurement protocol for evaluating “green” buildings.
Authors: Roy Kenneth P.
Published: October 2009

Since a majority of buildings have been shown to be “acoustically challenged,” and since “Green” design has only recently begun to address acoustic needs, when the USGBC approached ASHRAE to develop performance measurement protocols (PMPs), acoustics was included as a building IEQ factor. Accordingly, the PMP document provides guidance for the measurement and reporting of building performance, and includes protocols for performance measurement of energy use, indoor environmental quality, and water use. The IEQ protocols apply to thermal comfort, indoor air quality, lighting, and acoustics. The purpose of the PMP is to provide a consistent set of protocols, over a range of cost/accuracy, to enable an appropriate and accurate performance comparison of buildings, especially those claiming to be green, sustainable, and/or high performance. The protocols identify what is to be measured, how it is to be measured, and how often it is to be measured. Additionally, the protocols where developed for three levels of cost/accuracy (low, medium, and high), to provide realistic choices for consistent performance benchmarking. Design of buildings to meet high levels of acoustic performance will require a higher “level of proof” that those design goals have, in fact, been met. This document will be reviewed.
Mechanical system noise control in green laboratory design.
Authors: Markham Benjamin , Sturz Doug , Fullerton Jeffrey
Published: October 2009

The goals of energy efficiency and low noise are often mutually supportive in the design of mechanical systems for laboratories. This presentation outlines some basic design principles for indoor and outdoor noise controls of laboratory mechanical systems designed to be sustainable and energy efficient. Two themes emerge: the inherent connection between improving energy efficiency and minimizing noise (and minimizing the need for sound attenuation devices that increase system pressure and hence decrease efficiency) and the occasional conflicts between energy efficiency and low noise. The practical pros and cons of specific design guidelines and noise control strategies will be presented, focusing on systems with high-energy efficiency and relatively low system pressures and airflow velocities. Some examples of covered topics include equipment selection guidelines, laboratory exhaust discharge attenuation design or avoidance strategies, variable speed drive design for cooling tower applications, duct layout guidelines, duct leakage requirements, and sound attenuator usage and selection strategies.
Noise and energy consumption in heating, ventilation and air conditioning systems.
Authors: Sanders Philip , Rumsey Peter
Published: October 2009

Reduced noise and reduced energy consumption are often inter-related in HVAC systems. This presentation reviews some simple engineering principals supporting this assertion and uses case studies to illustrate it. Acoustical consultants collaborating with architects and mechanical engineers may be able to use this information to show the acoustical benefits of energy efficient heating and cooling systems, thus influencing owner decisions in favor of HVAC systems that consume less energy.
Effects of prosodic structure on the relative timing of articulators in English lateral production.
Authors: Lin Susan S.
Published: October 2009

Previous research has established that American English speakers tend to produce syllable-final /l/ with movement of the tongue dorsum preceding movement of the tongue tip. However, the results of these studies differ with respect to the articulator timing in syllable-initial /l/, with some claiming synchrony (Browman and Goldstein, 1995) and others claiming asynchrony in the direction opposite that of syllable-final /l/ (Gick, 2003). This study uses ultrasound imaging to investigate the relative timing of the tongue tip and dorsum during production of syllable-initial and syllable-final /l/ in multiple prosodic contexts. Prosody has a significant effect on both duration and extent of articulator movement in speech production—onsets of larger prosodic units involve larger and longer movement than onsets of smaller prosodic (Keating, 2006). The explanation that these effects result from speakers’ attempts to render perceptually more clear the segments that initiate phrases and utterances suggests that examining these segments at varying prosodic positions may provide insight into speakers’ knowledge of speech perception. Current preliminary results show that American English speakers may utilize at least two distinct timing relations in initial laterals, supporting a position that speaker knowledge may be variable between speakers.
The effects of “Smooth Speech” on the phonetic features of stuttered speech: A case study.
Authors: Menezes Caroline , Ellis Lee
Published: October 2009

This is a preliminary study focused on analyzing the acoustic characteristics of stuttered speech before, during, and after a short treatment using the Smooth Speech protocol. Smooth Speech technique, among other strategies, teaches stutterers to consciously control air-flow during speech through continuous airflow, gentle onsets for vowels, and soft contacts with consonants and to synchronize speech phrasing structure with the breath stream. In our case study Smooth Speech was shown to have a noticeable impact on the intelligibility and fluency of the speaker’s speech immediately following training. This study is a preliminary investigation to understand the phonetic features, both segmental and supra-segmental, that were specifically effective in increasing speech intelligibility. Speech samples included a monolog a read passage for both pre-test and post-test sessions, and a monolog for the training period. Acoustic analysis included evaluation of phoneme duration, syllable duration, pause durations, and pitch range. Phrasing structure was also analyzed. We conclude with a discussion on the relationship of speech rate and breath control and its effect on intelligibility.
Classifying place of articulation and palatalization of fricatives based on cepstral coefficients and spectral moments.
Authors: Spinu Laura , Lilley Jason , Vogel Irene , Bunnell H. Timothy
Published: October 2009

Hidden Markov models (HMMs) with two types of acoustic features were used to classify fricatives by place of articulation and palatalization status. The data were recordings of 31 native speakers of Romanian who produced a total of 3674 fricatives. Segments from four places (labial, alveolar, postalveolar, and dorsal) were examined, each of which appeared as plain and palatalized (with a palatal secondary articulation). Both the fricatives and the preceding vowels were divided by HMM training into three acoustically uniform regions, corresponding to the three states of the HMM models. Separate sets of monophone HMMs were trained using (a) the first four spectral moments plus rms amplitude and (b) the first five Bark-cepstral coefficients. Generally, the first and second regions/states of the fricatives were more important in classifying the segments by place, while the third state contributed more to the classification by palatalization status. The success of the classification depended on the specific combination of predictor variables (acoustic features and regions) used. Thus, the overall accuracy in classifying segments according to place or palatalization ranged from 62% to 95%. These analyses shed light on the differential distribution over time of acoustic features related to place and palatalization.
Acoustic cues to the voicing contrast in developing coda stop consonants: Toward comparison with adult caregivers.
Authors: Hanson Helen M. , Shattuck-Hufnagel Stefanie , Capotosto Margaret
Published: October 2009

Hanson and Shattuck-Hufnagel (Proceedings of Acoustics ‘08) analyzed coda stop consonants for three children from the Imbrie corpus (A. Imbrie, Ph.D. thesis, MIT, 2005). Following the closure, voice bars were frequently observed in [+voice] stops, while [−voice] codas often had a period of noise overlapping the preceding vowel and extending into the closure. Possible explanations for this noise include motoric immaturity, imitation of something in their caregivers’ productions, or the child’s decision to provide additional cues to the voicing contrast (enhancement). In this study, the second possibility was investigated in recordings of each child’s primary caregiver. Coda stop consonants were analyzed in the words “bug,” “tub,” “cup,” and “duck,” specifically the durations of voice bars and vowel-final noise. As expected, voice bars mainly occur in voiced codas; in contrast, vowel-final noise occurs mainly with voiceless codas, and its duration and degree of overlap with the vowel/closure vary across subjects. Similar measures for the children will be compared with those of their primary caregivers. [Work supported by NIH Grants Nos. DC00075 and DC 008780, and a NSF CPATH grant.]
Transitional cues in fricative noise in Greek /s/-stop and stop-/s/ sequences: Children versus adults.
Authors: Syrika Asimina , Edwards Jan R. , Li Fangfang , Beckman Mary E. , Munson Benjamin
Published: October 2009

Greek is one of the few languages to allow /s/-stop and stop-/s/ sequences at three places of articulation (bilabial, dental, and velar) in word-initial position. This study measured the coarticulation of /s/ with the following or preceding stop in native Greek-speaking children’s and adults’ productions of real words beginning with /sp/, /st/, /sk/, /ps/, /ts/, and /ks/, in a variety of vowel contexts. The aim was to determine whether stop place cues are signaled effectively in the spectrum of adjacent /s/ in both types of consonant sequences attested in Greek. Fast Fourier transform spectra were calculated for overlapping 10-ms windows from the beginning to the end of fricative noise and spectral moments were computed in each window. Systematic differences in the fricative spectra as a function of the adjacent stop consonant were observed in the /s/+stop sequence (as in English) and also in the stop+/s/ sequence (where the differences in the portion after the stop burst proper mirrored the patterns at the end of the fricative in the clusters in the other order). Coarticulation was comparable across age groups, although there was greater variability in children’s productions. [Work supported by NIDCD Grant No. R01DC02932 and NSF Grant No. BCS-0729140.]
Phonetic realization of glottal stop in Shugni.
Authors: Bao Mingzhen
Published: October 2009

Shugni is an underdocumented Indo-European language, mainly spoken in the Pamir mountains. Orthographically, Shugni used the apostrophe to symbolize the glottal stop phoneme, and the symbol only occurred word initially. In this paper, phonetic manifestation of glottal stop was examined, and the adjacent vowel [a] was compared under five conditions: (1) word-initial glottal stop followed by [a] and a consonant #[ʔaC1], (2) word-medial [C2aC1] sequence where [a] was also syllable-medial, (3) word-medial [C2aC1] sequence where [a] was syllable-final, (4) word-final [a] preceded by a consonant [C2a]#, and (5) a sequence of [C2a]# [ʔaC1] where glottal stop was word-initial and intervocalic. Four acoustic parameters were measured, and glottal stop was defined as (1) an absence of formant transitions entering or leaving [a], (2) an abrupt start or end of [a]’s magnitude, (3) identifiable stop closure, and (4) irregular pulses produced by glottal tension. The results showed that irregular pulses were noticed in some but not all [a]s of words which began with the apostrophe. No other significant acoustic differences were noted among conditions. The results suggested that glottal stop in Shugni be described as non-phonemic vowel laryngealization or creaky phonation. The word-initial apostrophe had to be treated cautiously to interpret the variation.
Investigating the incomplete neutralization of flaps in North American English.
Authors: Colley Michael
Published: October 2009

The flapping of intervocalic apical stops in American English results in the neutralization of voicing in words like writing and riding, as compared to write and ride. Some evidence has suggested that speakers maintain a distinction in the length of the vowel preceding the flaps, thus making the neutralization incomplete [e.g., Patterson and Connine (2001)]. Proponents of the idea of incomplete neutralizations often use it to challenge the idea of discreteness of phonetic categories [Port (1996)]. However, claims of incomplete neutralizations in English and other languages have not been universally accepted [Manaster Ramer (1996)]. This study tests whether listeners are able to use differences in vowel durations before flaps to determine the underlying voicing of flaps in pseudo-words. To avoid any influence from orthography, the pseudo-words were presented as auditory stimuli to the participants, and the responses were recorded orally. Participants who heard stimuli in which one set of vowels were 20 ms longer than the other set were more likely to interpret the flaps as /t/ than participants who heard stimuli in which all pre-flap vowels had identical durations. However, participants were not able to use the differences in vowel durations to determine the underlying voicing of the flaps.
Nasal coarticulation in clear speech.
Authors: Brasher Anthony
Published: October 2009

This study tests whether speakers, when trying to speak clearly, employ variable enhancement strategies as a function of phonetic environment. Using aerodynamic and acoustical methods, this study examines the effects of phonemic context and speaking modality and on the spatial and temporal extent of anticipatory nasal coarticulation in English. Target words are English (C)VNCvoiced (e.g., bend) and (C)VNCvoiceless (e.g., bent) words spoken in either clear or citation speech modes. In order to enhance the percept of /n/ in clear speech, speakers increase the duration of the nasal consonant in CVNCvoiced words but marginally increase, or even decrease, /n/ duration in CVNCvoiceless words. While highly variable, airflow results suggest little difference on anticipatory nasalization as a function of speech mode. These results argue against models predicting a global reduction in coarticulation in clear speech.
Lexical tone and segmental coarticulation.
Authors: Agwuele Augustine
Published: October 2009

In studying anticipatory coarticulation in emphatic CV sequences [Lindblom et al., J. Acoust. Soc. Am. 121, 3802–3813 (2007)] and in fast speech [Agwuele et al., Phonetica 68, 194–209 (2008)], it was shown that prosodically induced modulations of speech introduce additional sources of phonetic variation separate from those generated by vowel context. Both studies were successful in dissociating these additional prosodic effects from the underlying contextual vowel variation and quantifying them. The focus of this current investigation was to study CV coarticulation, using a similar set of regression metrics, but now applied to a tonal language (Yoruba). It is to be determined whether lexical tone impacts the coarticulation of consonant and vowel. Specifically, words, do tones, produce additional effects on anticipatory CV coarticulation separate from those generated by vowel-context similar to emphatic stress and increased tempo as documented by the aforementioned studies? Finally, of interest also is to examine whether different lexical tones impact C+V coarticulation differently.