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Journal of the Acoustical Society of America

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Oct 2011

Volume 130, Issue 4, pp. EL129-2575

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Sound absorption of different green roof systems (A)

Ilaria Pittaluga, Corrado Schenone, and Davide Borelli

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2317-2317 (2011); (1 page)

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Experimental data on acoustical performances, in particular on sound absorption, of several green roof systems were evaluated and discussed. Measurements were performed on samples of three green roof systems, different for maintenance, plant setting and containment criteria, and categorized in extensive green roof (sample A), semi-intensive green roof (sample B), and common soil (sample C). Experimental values of normal incidence acoustic absorption coefficient and acoustic impedance were evaluated for each sample in one-third octave frequency bands from 160 to 1600 Hz by using a standing wave tube. Then, diffusive sound absorption coefficients and normal and diffusive weighted sound absorption coefficients were calculated in the same frequency range. Results show that green roofs provide high sound absorption, mostly if compared with the typical performances of traditional flat roofs. Curves of sound absorption coefficients result strongly dependent on the stratigraphy. Comparison between the different systems performed on the base of weighted sound absorption coefficients shows a better behavior for the sample B. Results obtained suggest that green roof technology, in addition to energy and environmental benefits, can contribute to noise control in urban areas by means of high sound absorption performances in relation to the size of the surface area.
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43.55.Ev Sound absorption properties of materials: theory and measurement of sound absorption coefficients; acoustic impedance and admittance
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Acoustic properties of green walls with and without vegetation (A)

V. Kirill Horoshenkov, Amir Khan, Hadj Benkreira, Agnès Mandon, and Rene Rohr

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2317-2317 (2011); (1 page)

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One substantial issue with the majority of modern methods for noise control is their heavy reliance on man-made acoustic structures which require continuous service and maintenance. In this respect, the use of the inherent noise control properties of vegetation appears particular attractive compared to other street/square treatments for reducing noise such as adding façade absorption and diffusion. A green wall with a carefully selected type of soil substrate provides an alternative to more conventional types of acoustic treatment. This work studies the influence of leaves (foliage) on acoustic absorption of soils, plants, and their combination which are typically used in green (living) walls. It is shown the the presence of plans with a particular type of leaves can result in a considerable (up to 50%) improvement in the absorption coefficient of a green wall with soil at a certain water saturation. The acoustic absorption coefficient of these systems is examined here through laboratory measurements and theoretical prediction models. The plants in this study were chosen to cover a range of possible leaf types, sizes, and densities.
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43.55.Ev Sound absorption properties of materials: theory and measurement of sound absorption coefficients; acoustic impedance and admittance
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Analysis of sound propagation in an experimental model using a high resolution scanning system (A)

Aditya Alamuru, Ning Xiang, and Joonhee Lee

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2317-2317 (2011); (1 page)

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The aim of this work is to analyze low frequency and mid frequency sound propagation in a coupled volume system for different aperture configurations. The cross sectional areas of the primary room and the secondary room are scanned over high spatial resolution grids using an automated scanning system. This procedure is carried out systematically for different aperture configurations. A dedicated analysis algorithm converts experimentally measured room impulse response data at each grid point into energy distributions and instantaneous sound pressure levels as a function of time. The analysis algorithm provides streams of data for a selected frequency thereby creating an animation of sound propagating through the coupled volume system. This work will demonstrate wave phenomena for different aperture configurations at low frequencies and mid frequencies by using animations to analyze the experimentally measured data.
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43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
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Architectural acoustic elements to reduce the decay time in a room (A)

Bonnie Schnitta, Melissa Russo, Greg Greenwald, and Michael Cain

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2317-2317 (2011); (1 page)

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The paradise architectural acoustic devices are sound modifying architectural elements, or structures. The architectural structure can be made to look like any one of the standard architectural structures commonly used in a room, from baseboards to crown moldings or ceiling beams. Depending on the intended outcome, the architectural elements can either be a solid body, or what appears to be a solid element but has internal mathematically determined channels. This allows the architectural elements, or devices, to not only reduce or correct the decay time in the room, but also make certain that the architectural elements do not produce undesirable effects. The mathematical foundation of the various shapes and designs of the architectural acoustic structures, or elements, will be presented for a linear case. This will allow a better understanding of the underlining acoustical effects. An appreciation for a more precise mathematical description of the embodiments will also be discussed by additionally taking into account the nonlinear aspects of the various embodiments. Various views of an acoustic architectural device for reducing or correcting decay time will be presented. Additionally, the improvements to the acoustic environment of the room that result from the paradise architectural elements will be provided.
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43.55.Ev Sound absorption properties of materials: theory and measurement of sound absorption coefficients; acoustic impedance and admittance
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Analyzing the auditory nature of architecture (A)

Daniel Butko

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2318-2318 (2011); (1 page)

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Architects usually place primary focus on the physical nature of materials and the aesthetic qualities of how those various materials are assembled. Although visual appeal is quite valuable when creating the built environment and specific inhabitable space(s), attention to sound is also vital in making a project successful for its intended use and daily occupants. Third year architecture students at the University of Oklahoma were tasked with a series of analytical studies and experiments that focused on the auditory nature of the built environment. This served as a precursor to the semester design project. The students spent time listening and discovering what sounds and noises were present within various functions. Each student categorized their individual findings of analyzed space into three classifications: (1) What sounds and/or frequencies they deemed successful/helpful to the intended use, (2) What sounds and/or frequencies they deemed unsuccessful/hindrance to the intended use, and (3) What additional sounds or noises they believe could have supported the intended use. The results were presented in class, discussed among the entire group, and ultimately fueled the students' future design decisions. This paper focuses on how simple analytical auditory studies can alter the overall design process to include architectural acoustics.
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43.55.Gx Studies of existing auditoria and enclosures
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Acoustic simulation of renaissance Venetian churches (A)

Braxton B. Boren and Malcolm S. Longair

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2318-2318 (2011); (1 page)

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The Venetian Renaissance was a confluence of innovative expression across many artistic disciplines. While architects like Palladio and Sansovino were designing architectural masterpieces in many of the churches built during this period, composers such as Willaert, the Gabrielli, and Monteverdi were composing complex polyphonic works for split-choir ensembles, exploring the tonal and spatial dimensions of musical performance. The large churches built during this period have extremely long reverberation times and provide low clarity for understanding the complex polyphony composed for these spaces. This paper uses modern acoustic simulation techniques to provide insights into the acoustics of large Venetian churches as they would have existed during the Renaissance. In consultation with architectural historians, the authors have collected data on the structure and layout of Palladio's Redentore and San Marco on festal occasions, when large crowds, extra seating, and wall tapestries would have provided extra absorption. Using Odeon, acoustic simulations predict that under festal conditions these churches would have had significant improvements in T30, EDT, and C80. The doge's position in San Marco's chancel has particularly good clarity for sources located in Sansovino's galleries, supporting historian Laura Moretti's hypothesis that these galleries were installed for the performance of split-choir music.
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43.55.Ka Computer simulation of acoustics in enclosures, modeling
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Temporal modeling of measurement conditions to enhance room acoustical parameter characterization (A)

Stephen Roessner, Gang Ren, Mark F. Bocko, and Dave Headlam

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2318-2318 (2011); (1 page)

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Forming statistical combinations of the results of repeated acoustical measurements taken under identical conditions is a common practice to reduce the effects of random noise. The most common method is to calculate the arithmetic mean of an ensemble of test results, which is based on the assumption that all experiments were conducted under identical noiseless test conditions. For most room acoustic measurement scenarios, this assumption is not valid, and non-stationary sources of noise often contaminate the results. Traditional statistical averaging methods can be improved by explicitly modeling the ambient interference and noise. Using a signal model for the noise and interference, the proposed parameter estimation procedure provides more accurate results than simple averaging in low signal to noise ratio test scenarios. This method, in which multiple, low volume measurements replace high volume test signals, provides a practical and cost-effective approach for characterizing acoustical spaces.
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43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
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Benchmark measurements of noise, reverberation time, and an estimate of speech intelligibility in a representative operating room at Nationwide Children's Hospital in Columbus, Ohio (A)

Richard D. Godfrey, Lawrence L. Feth, and Peter Winch

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2318-2318 (2011); (1 page)

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Nationwide Children's Hospital was interested in understanding speech communications: in their operating rooms and between the parents/child and the doctor in pre-operative rooms. Long-term hearing loss of the staff was of secondary interest. Before a comprehensive project was proposed, data in a single OR to gain some experience was conducted. A SLM was programmed to measure the following during 15 s intervals: overall A-weighted equivalent energy sound level, A-weighted equivalent energy sound level in octave bands from 16 to 16 kHz, and peak un-weighted level during the interval. Reverberation was also measured by an impulsive method. Measurements were made for 23 consecutive hours. The data were downloaded for analysis. It was concluded that (1) adding some absorption around the top of the walls would improve SI, (2) good SI is only possible with a high vocal effort, and (3) long term hearing loss is very unlikely. Follow up topics before a comprehensive project is proposed were (1) try other reverberation methods, (2) study more rooms while a variety of surgical procedures are performed, (3) identify the source and duration of peaks levels, and (4) investigate other measures of SI.
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43.55.Hy Subjective effects in room acoustics, speech in rooms
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Impacts of classroom acoustics on elementary student achievement (A)

Lauren M. Ronsse and Lily M. Wang

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2318-2318 (2011); (1 page)

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This research investigates relationships between unoccupied classroom acoustical conditions and elementary student achievement. Acoustical measurements were gathered in all of the third and fifth-grade school classrooms (67 total) in a public school district in north-eastern Nebraska, USA. Traditional classroom acoustic parameters, including background noise level and reverberation time, have been correlated to the standardized achievement test scores from students in the surveyed classrooms. Binaural impulse response measurements were also conducted in a subset of the rooms (20 total) and correlated to the student achievement scores. Acoustical metrics calculated from the binaural impulse response measurements include speech transmission index, distortion of frequency-smoothed magnitude, interaural cross-correlations, and interaural level differences. The results from this research indicate that scores on fifth-grade student language and reading subject areas are negatively correlated to higher unoccupied background noise levels. Also, the distortion of frequency-smoothed magnitude, which is a perception-based acoustics metric, was significantly related to the student language achievement test scores.
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43.50.Qp Effects of noise on man and society
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A survey of residential “speaking tubes.” (A)

William J. Elliot and John T. Foulkes

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2318-2318 (2011); (1 page)

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The speech transmission index is examined for a system of “speaking tubes” within a home in the Avon Hill neighborhood in Cambridge, Massachusetts. Designed in 1888 by noted Boston architects Henry Hartwell and William C. Richardson, the Shingle Style home was both wired for electricity and outfitted with piping for gas. An electronic paging system was used to summon servants, but when aural communication was necessary, the speaking tube system was used for inter-floor communication. This paper examines the measured STI for the speaking tubes which remain in the home within the context of simple passive waveguide sound propagation. The paper also provides a quantitative evaluation of this pre-electroacoustic technology as it appeared in several fashionable homes of the late 19th and early 20th centuries.
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43.72.Kb Speech communication systems and dialogue systems
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Comparison of the articulation test and speech transmission index values measured in two different acoustical poor conditions (A)

Jorge Sommerhoff and Claudia Rosas

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2319-2319 (2011); (1 page)

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In this work, a comparison is made between articulation tests and speech transmission index (STI) values, measured in the same place, in two different acoustically poor room conditions, both with STI values of less than 0.4. In the first room condition, a 200 m3 reverberation chamber with background noise of less than 32 dBA was used. In the second room condition, pink noise was added to a small room with reverberation time of less than 0.6 s, till values of STI lower than 0.4 were reached. The articulation test corpus consisted in a 1000 phonetically Spanish combination of a consonant, vowel, and consonant (CVC logatoms). The logatoms were recorded in an anechoic chamber. In the articulation test and STI measurement, both signals were emitted in the rooms using a NTI Talkbox with a sound power equivalent to a normal human voice. The STI and articulation was measured at the listener's seats which were located at different distances from the source but within STI values less than 0.4. The articulation test results of both acoustical conditions are correlated separately with the measured STI. The results of the measurements indicate that for the same STI value, the subjective response statistically differs.
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43.71.Gv Measures of speech perception (intelligibility and quality)
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The effect of listener head movement on perceived envelopment and apparent source width (A)

Anthony J. Parks

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2319-2319 (2011); (1 page)

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Current research examining listeners' perceived spatial impression of a concert hall relies on a fixed-head worldview, since the overwhelming majority of listening tests conducted to determine subjective spaciousness [listener envelopment (LEV) and apparent source width (ASW)] has required listeners to keep their heads fixed. Such a worldview is an incomplete one, because listeners make noticeable exploratory head movements while evaluating sonic environments, including the more common task of source localization as well as the more involved task of evaluating the spaciousness of a concert hall. This study investigates the role of listener head movement in the evaluation of perceived LEV and ASW under 15 different concert hall conditions simulated over eight loudspeakers using Virtual Microphone Control. The conditions consist of both varying ratios of front-to-back energy and varying levels of cross-correlated reverberant energy. Head movements are monitored in terms of angular rotation (azimuth, elevation, and roll) using a head tracker while listeners are prompted to give subjective ratings of LEV and ASW ranging from 1 (least) to 7 (most). The listening tests are then repeated while subjects are asked to keep their heads fixed. The head movements are analyzed and results of the tests are compared.
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43.55.Hy Subjective effects in room acoustics, speech in rooms
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Applications of a binaural model with contralateral inhibition in room acoustics analysis (A)

Timothy Perez, Jonas Braasch, and Ning Xiang

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2319-2319 (2011); (1 page)

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In many cases the conventional, monophonic measures used in analyzing room acoustics show little agreement with real listeners' responses; a binaural perspective provides much-needed spatial and perceptual information that is important in acoustical quality judgments. Traditionally, binaural models extracted information about location and intensity of sound through a relatively simple cross-correlation procedure. This paradigm was extended by Lindemann [J. Acoust. Soc. Am. 80, 1608–1630 (1986)] with the introduction of a contralateral inhibition process, which applies a time- and intensity-dependent weighting to a pair of binaural signals and accurately reproduces results from psychoacoustical tests where the traditional model fails, such as in the case of the Precedence effect. The model will be used to observe the broadening and splitting of auditory events based on the degree of interaural coherence, providing further validation of its adequacy. Then, applications in architectural acoustics will be investigated by processing binaural room impulse responses and producing a binaural activity pattern, which indicates the location and spatial extent of the resulting auditory events. These will be compared to visualizations drawn from spherical harmonic microphones. Implications of such a model on factors important in acoustical quality assessments, such as apparent source width and listener envelopment, will be discussed.
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43.55.Hy Subjective effects in room acoustics, speech in rooms
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The audibility of direct sound as a key to measuring the clarity of speech and music (A)

David H. Griesinger

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2319-2319 (2011); (1 page)

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Human ear/brain systems evolved to decode the direction, timbre, and distance of multiple sounds in a complex and noisy environment. In a reverberant space, this information is only available at the onset of a sound, before reflections overwhelm it. But since the time of Sabine acoustic science has concentrated on the decay of sound in a reverberant field, not on the audibility of the onset information. In addition, it is well known that the ability to separate multiple sound sources depends critically on pitch, but acoustic research studies only noise and impulses. This paper proposes that clarity requires the ability to separately analyze multiple sounds (the cocktail party effect) and that the cocktail party effect depends on phase relationships between harmonics of complex tones. These phase relationships are scrambled in predicable ways by reflections and reverberation. Well known properties of human hearing are used to develop both a physical model for the neurology of onset detection and an impulse response measure for localization and clarity in a reverberant field. A C language implementation of the physical model is capable of predicting and perhaps measuring the localizability of individual musicians in a binaural recording of live music.
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43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
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Sound metric design based on psychological and physiological acoustics for the analysis of automotive sound (A)

Young Joon Lee, Hong Sug Park, and Sang Kwon Lee

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2319-2319 (2011); (1 page)

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This paper presents the correlation between psychological and physiological acoustics for the automotive sound. The research purpose of this paper is to evaluate the sound quality of interior sound of a passenger car based human sensibility. The conventional method for the objective evaluation of sound quality is to use the only sound metrics based on psychological acoustics. This method used not only psychological acoustics, but also physiological acoustics. For this work, the sounds of five premium passenger cars are used for the subjective evaluation. The correlation between this subjective rating and sound metrics based on psychological acoustics is calculated. Finally, the correlated sound metric is used for calculating the correlation between sound metric and the electron cephalogram signal measured on the brain. Throughout these results, the new evaluation system for the sound quality on interior sound of a passenger car has been developed.
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43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles
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Marine acoustic ecologies and acoustic habitats: Concepts, metrics, and realities (A)

Christopher W. Clark, Aaron N. Rice, Dimitri W. Ponirakis, and Peter J. Dugan

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2320-2320 (2011); (1 page)

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Whales, dolphins, and porpoises (cetaceans) are adapted to produce and perceive sounds that collectively span 4–6 orders of magnitude along space, time, and frequency dimensions. Two important concepts, acoustic ecology and acoustic habitat, emerge from this perspective: where acoustic ecology is the study of acoustics involved in interactions of living organisms, and acoustic habitat as ecological space acoustically utilized by particular species. Cetaceans are dependent on access to their normal acoustic habitats for basic life functions. Communication masking from anthropogenic sounds that are chronically present can result in measurable losses of cetacean acoustic habitats, especially for low-frequency specialists, baleen whales. A communication masking model, informed by multi-year datasets, demonstrates cumulative influences of multiple vessels on fin, humpback and right whale acoustic habitats at spatial, temporal, and spectral scales matched to ecologically meaningful habitats. Results quantify acoustic habitat spatio-temporal variability over ecologically meaningful scales. In some habitats with high vessel traffic and vessel noise, predicted habitat loss and area over which animals can communicate is dramatically reduced compared to what it would be under non-vessel conditions. From a large-scale, ecological perspective, these acoustic habitat reductions likely represent significant costs for species for which acoustic communication is biologically critical.
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43.80.Ev Acoustical measurement methods in biological systems and media
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Evaluating the potential spatial extent of chronic noise exposures of sufficient magnitude to raise concerns of wildlife impacts (A)

Kurt M. Fristrup

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2320-2320 (2011); (1 page)

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Noise is probably the fastest growing pollutant in the United States. Traffic levels for many forms of transportation and recreation are increasing in much faster rates than population size. The consequences of chronic noise exposure for natural ecosystems are numerous and potentially severe. Decreases in pairing success, recruitment, population density, and community diversity have been documented for a variety of taxa. This presentation provide a capsule summary of documented biological impacts. These findings will be used to interpret the results from acoustical monitoring in a variety of National Park units, as well as predictions from noise models.
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43.80.Ev Acoustical measurement methods in biological systems and media
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Endangered Stephen's kangaroo rats respond to road noise with footdrumming (A)

Debra M. Shier, Amanda J. Lea, and Megan A. Owen

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2320-2320 (2011); (1 page)

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On-road vehicles have become a pervasive source of low frequency noise in both urban and protected areas. Because many species rely on low-frequency signals to communicate, they are likely vulnerable to signal masking and other adverse effects of road noise exposure. We recorded and quantified both road noise and low frequency footdrumming signals from endangered Stephen's kangaroo rat (Dipodomys stephensi; SKR), and found the two signals to overlap extensively. We then played back footdrumming overlaid with experimental (road noise), as well as positive (crickets) and negative control (no noise) sounds to SKR. SKR showed no response to footdrumming playbacks overlaid with road noise, suggesting that noise may mask conspecific signals. Furthermore, playbacks of road noise alone provoked similar behavioral responses to those of footdrumming controls. It appears that road noise itself may mimic footdrumming and prompt a false response in SKR. Therefore, anthropogenic noise may not only mask signaling, it may also function as a deceptive signal to wildlife. For SKR, the combined effects of communication disruption and signal deception may further tax already endangered populations. Road margins serve as dispersal corridors and refugia for SKR, yet these areas may function as ecological traps if anthropogenic noise negatively affects populations.
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43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms
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Influence of impulsive sources on the soundscape of under-ice Arctic marine mammals (A)

Juan I. Arvelo, Jr.

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2321-2321 (2011); (1 page)

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The Arctic Ocean exemplifies the danger in using sound propagation and interaction models without a clear understanding of the physics of the problem or weaknesses inherent in these models. The zone-of-influence for under-ice marine mammals should be expected to differ significantly from that of open-sea organisms. However, increasing the effective sound attenuation, to empirically account for sound interactions with keel drafts, may lead to grossly erroneous conclusions from predictive and forensic studies. Ice elasticity and ridges combine to increase water/ice low-frequency sound penetration enabling long-distance transmission along this liquid–solid interface in the form of an evanescent wave. Consequently, sound pressure and exposure levels near the canopy are significantly higher even when the acoustic wavelength is several times longer than the ice thickness. Therefore, these physical mechanisms should also be taken into account in Arctic environmental impact assessment calculations. For example, it is more efficient for under-ice marine mammals to mitigate exposure to subsequent active sonar events by diving just a few meters deeper under the ice cap rather than increasing range by hundreds of meters. Therefore, some under-ice marine mammals are likely to exhibit a stronger preference toward diving avoidance behavior. [Work funded by UAF sub-award under NOAA Grant NA09NOS4000262.]
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43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
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Seasonal presence of ringed, ribbon, and bearded seal vocalizations in the Chukchi Sea north of Barrow, Alaska (A)

Joshua M. Jones, Ethan Roth, Bruce J. Thayre, Ian Sia, Michael Mahoney, Clarissa Zeller, Malorie Johnson, Christine Jackson, Kyle Kitka, Daniel Pickett, Robert Small, Zoe Gentes, Sean Wiggins, and John Hildebrand

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2321-2321 (2011); (1 page)

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Long-term autonomous acoustic recordings were collected between September and June from 2006 through 2009 in the Northeastern Chukchi Sea along the continental slope 120 km north of Barrow, Alaska. These recordings were analyzed for the presence of vocalizations of ringed seals (Phoca hispida), ribbon seals (Histrophoca fasciata), and bearded seals (Erignathus barbatus). We present detailed descriptions of the acoustic repertoire of each species in addition to three-year time series of seal vocalizations and mean daily sea ice concentration. Ringed seal vocalizations are present throughout each winter and spring, indicating that they both overwinter and breed in offshore pack ice. Ribbon seal calls occur only during the open water period in 2008, but their acoustic behavior is more varied than previously described. Bearded seal vocalizations closely match well-documented calls recorded offshore near Point Barrow but have shorter duration and smaller frequency range, suggesting that demographic or behavioral differences related to breeding habitat selection may exist within the population. Bearded seal calls peak during the breeding season from March through June, but also occur in December and January annually. These long-term autonomous recordings provide details of seasonal distribution and behavior of Arctic seals that previously have not been possible to observe with other methods.
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
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The acoustic ecology of minke whales in the tropical north pacific (A)

Thomas Norris, Steven W. Martin, Tina M. Yack, Len Thomas, and Julie Oswald

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2321-2321 (2011); (1 page)

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The minke whale (Balaenoptera acutorostrata) is a ubiquitous but rarely sighted species that occurs in subtropical waters of the North Pacific during winter and spring. It produces a unique vocalization called a boing that is easy to detect and localize. We characterized the acoustic ecology of minke whales by detecting and localizing boings using passive acoustic methods. We conducted passive acoustic line-transect surveys in 2006 for a large area around the Northern Mariana Islands (site 1), and in 2010 for a smaller area off the Pacific Missile Range, Kauai, HI (site 2). We also recorded acoustic data from deep waters using cabled seafloor hydrophones at site 2. Densities of calling animals were estimated from line-transect surveys and will be used to estimate calling rates for use in spatially explicit capture–recapture analysis of fixed seafloor hydrophone data. Spatial analysis of acoustic localizations in relation to bathygraphic and oceanographic variables will be discussed. We provide examples of counter-calling and complex responses to vessel noise. These results provide important information about the acoustic ecology and behavior of minke whales that can be used to improve the conservation and management of this elusive but common whale. [Work sponsored by ONR and NAVFAC.]
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
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Characterizing the vocalizations of North Atlantic right whales (NARWs) in Florida, with emphasis on mother-calf pairs (A)

Edmund Gerstein, James Hain, James Moir, and Stephen McCulloch

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2321-2321 (2011); (1 page)

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The repertoire of calls, frequency of occurrence with respect to social composition, and ontogeny of vocal learning is being investigated for NARWs in their southeastern critical habitat of Florida. Small synchronized, GPS-instrumented, digital autonomous recording packages (DARPs) are deployed in the vicinity of photo-identified individuals, mother-calf pairs, and groups. The unobtrusive DARP buoys enable the recording of relatively rare, low-intensity vocal exchanges between mothers and calves. We hypothesize that it may be advantageous to be silent or to call softly to avoid predators or harassment by males in the area. These mother-calf exchanges could also be related to early developmental aspects of vocal communication. Site-specific bathymetry and active propagation measurements are conducted with vertical arrays to estimate source levels, and ranges of detection. Preliminary data indicate that exemplar (up-calls) recorded in northern habitats and used for training detection algorithms for passive auto-detection buoys are likely not appropriate for Florida waters. Social demographics, associated behavior, along with water depth and environmental parameters contribute to differences in call rates, types, source levels and respective propagation characteristics between the southeastern and northern habitats. Critical acoustic data required for selecting more appropriate calls for effective DCL algorithms in Florida waters are currently being collected.
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
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Environmental influences on acoustic communication in frogs (A)

Peter M. Narins

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2321-2321 (2011); (1 page)

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Many species of animals, including man, face the formidable task of communicating in naturally noisy environments. The effects of noise on both the calling behavior of frogs and the temporal, and spectral filtering ability of the amphibian auditory pathway are discussed. Moreover, the role of spectral, temporal, and spatial separation in minimizing background noise masking will be examined. Behavioral evidence is presented suggesting that environmental noise may act as a strong selective force in sculpting the communication systems of two species of Old World frogs. One torrent frog (Odorrana tormota) calls frequently from vegetation along fast-flowing mountain streams in Central China. These streams produce high-level, broadband noise spanning the human hearing spectrum. In addition to the high-pitched audible components, the males' calls contain prominent ultrasonic harmonics. Another frog, Huia cavitympanum, lives in a very similar habitat in Borneo. Unlike O. tormota, Huia can modulate its call spectrum to produce purely ultrasonic calls. It is thought that the upward shift of the call frequencies and the upper limit of sensitivity of both O. tormota and H. cavitympanum are responses to the selection pressures from their noisy habitats. [Work supported by NIDCD DC-00222, Paul S. Veneklasen Research Foundation, UCLA Academic Senate (3501).]
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43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms
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Chorussing in delphinids (A)

V. M. Janik, P. Simard, L. S. Sayigh, D. Mann, and A. Frankel

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2322-2322 (2011); (1 page)

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The evolution of communication is strongly influenced by the social structure of animals. Here, we report how a group of offshore bottlenose dolphins in the Gulf of Mexico used chorusing of the same whistle type, while no such behavior was observed in inshore populations of the same species. We recorded 166 whistles from a group of 6 bottlenose dolphins in the Gulf of Mexico, 19 nm from the Florida coast. In an examination of the timing of whistle production, we found nine sequences in which there was considerable overlap (i.e., >50%) between whistles and another eight sequences with almost perfect overlap of the same whistle type produced by two to six animals simultaneously. Such synchrony was not expected by chance. To investigate how unique this behavior was, we also analyzed 300 h of recordings of inshore bottlenose dolphins in Florida and Scotland. In these data we found three non-significant cases of two animals showing >50% overlap. Thus, chorusing appears to be absent in inshore animals. Our data suggest that offshore bottlenose dolphins live in closed social units, which could be the result of enhanced difficulties in maintaining contact if home ranges are large.
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
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Tracking dolphins using long-term autonomous acoustic recorders (A)

Sean M. Wiggins, Martin Gassmann, Kaitlin Fraiser, and John A. Hildebrand

J. Acoust. Soc. Am. Volume 130, Issue 4, pp. 2322-2322 (2011); (1 page)

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Tracking marine mammals over long periods can provide information on their movement patterns including base-line behavior and responses to natural and anthropogenic stimuli. Autonomous acoustic recorders provide a cost effective and portable means of tracking these sounds over long periods, but until recently these devices have been restricted to tracking low-frequency large whales because of limited recording capabilities. In this paper, we will present long-term, passive acoustic tracking of high-frequency dolphin whistles and clicks using autonomous hydrophone recording arrays with kilometer- and meter-scale apertures.
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43.30.Sf Acoustical detection of marine life; passive and active
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