bluuebunny/crossref_metadata_2025 huggingface dataset:
Four mass coupled oscillator guitar model.
Authors: Popp John E.
Published: October 2010

Coupled oscillator models have been used for the low-frequency response (50–250 Hz) of a guitar [G. Caldersmith, “Guitar as a reflex enclosure,” J. Acoust. Soc. Am. 63, 1566–1575 (1978); O. Christensen, “Quantitative models for low-frequency guitar function,” in 103rd ASA Spring Meeting (1982) and J. Guitar Acoustics 6, 10–25 (1982); T. D. Rossing, J. Popp, and D. Polstein, “Acoustical response of guitars,” in Proceedings of Stockholm Music Acoustics Conference, Royal Swedish Academy of Music (1985), pp. 311–332]. These 2 and 3 mass models correctly predict measured resonance frequency relationships under various laboratory boundary conditions, but did not always represent the true state of a guitar in the players hands. The model presented has improved these models in three ways: (1) a fourth oscillator includes the guitar body; (2) plate stiffnesses and other fundamental parameters were measured directly and effective areas and masses were used to calculate the responses, including resonances and phases, directly; and (3) neck vibrations were calculated and measured and shown to effect the response significantly in some guitars. The calculated and measured resonances and phases agree reasonably well.
Which are the main management issues about noise in Uruguay 2010?
Authors: González Alice Elizabeth
Published: October 2010

Despite the fact that noise is not part of the management priorities of decision makers in Uruguay, conflicts about noise are being considered with increasing importance in the recent years. Mitigation measures and solutions are expensive and often difficult to implement, so the trend is to increase prevention in order to minimize correction measures. Focusing on management of some decision makers in the last years, it would be inferred that current management priorities in Uruguay are three: (1) The enactment of a National Regulation Act on noise pollution to homogenize the dissimilar criteria handled in the ordinances of the 19 departments in which Uruguay is administratively divided; (2) attention to conflicts generated by nightlife places in the neighborhoods, especially regarding the agglomeration of young people outside the clubs, that not only raise the environmental sound levels with their presence and voices, but also turn on audio equipment in their vehicles and generate other problems of connivance and security; (3) prevention of adverse occupational and environmental effects, which resulted in greater demands on noise impact studies for environmental authorizations, and systematic studies in occupational settings, including acoustic maps and periodic audiometric studies on staff exposed to high noise levels.
The Fortaleza noise mapping project: A tool for the definition of noise action plans for the airport, the light rail system, and the Ceara musical event.
Authors: Chavez Brito F. Aurelio , Coelho J. L. Bento
Published: October 2010

The Fortaleza noise mapping project was set up for the spatial representation of environmental noise indicators to obtain an essential tool to analyze and define strategies for noise pollution control in Fortaleza, Brazil. This is the first large-scale noise map drawn for a large city in Brazil. Noise emissions from the most important sources contributing to the sound environment of the city, namely, road traffic, railway noise, aircraft noise, industrial noise, and noise from entertainment areas, were included. The method followed a hybrid approach, essentially calculation complemented with experimental measurements for validation and calibration. The large-scale noise assessment allowed detailed studies of the noise impact of the Fortaleza International Airport, located well within the urban city area, the impact of the passage of the underground access light rail tunnel on the local soundscape, and the impact of the Ceará musical event, which, though being part of the city cultural program, takes place in central and seaside areas close to a public hospital. These studies will be presented and discussed in the context of a geographical area where the fair climate allows long hours spent outdoors.
Mode identified resonant ultrasound spectroscopy.
Authors: Ogi Hirotsugu
Published: October 2010

Resonant ultrasound spectroscopy (RUS) is a powerful tool for determining all independent elastic constants (Cij) of solids. Successful inverse calculation for Cij requires mode identification for measured resonance frequencies. In this lecture, two mode-identified RUS methods developed by the author are presented. One is the electromagnetic acoustic resonance (EMAR) [Ogi et al., J. Acoust. Soc. Am. 106, 660 (1999)]. Using a solenoid coil and static magnetic field, vibrations of a specimen are measured through the electromagnetic-force mechanisms. Detectable vibrational modes are controlled by changing the magnetic-field direction. Because of the noncontacting measurement, it is applied to measurements at high temperatures easily. The second method incorporates the laser-Doppler interferometry into RUS (RUS-LDI method) [Ogi et al., J. Acoust. Soc. Am. 112, 2553 (2002)]. The specimen is set on the needle piezoelectric tripod in vacuum, and its displacement distributions at resonances are measured by laser interferometry for mode identification. It was applied to determine the piezoelectric coefficients and internal-friction tensors as well as Cij of various piezoelectric materials, and also to thin-film Cij. Because the contributions of the piezoelectric coefficients and thin-film Cij to resonance frequencies are very small, correct mode identification becomes significantly important in their determination.
Effects of conflicting auditory information on selective attention to pitch.
Authors: Espinoza-Varas Blas
Published: October 2010

We studied how conflicting information interferes with selective attention to task-relevant differences in pure-tone frequency. Across the observation intervals of the discrimination task, the relevant frequency differences between target tones were positive, but within an observation interval, they could appear to be small or negative relative to conflicting differences in flanker tones leading or trailing the target. Being correct required attending to the between-target and ignoring the target-flanker pitch relation (across and within observation-interval, respectively). The interference index was an elevation of conflict-laden frequency discrimination thresholds (FDTs), relative to no-conflict FDTs. When conflicting differences in frequency or level trailed the relevant differences, interference was large and persistent, increased with the target-flanker time proximity, but decreased with extensive training. Interference occurs when the target-flanker pitch relation is more prominent than the one between targets, and the physical and/or perceptual effects of relevant and conflicting differences tend to cancel one another, as with the above conflicting differences. With untrained participants, the target-flanker pitch relation is most prominent in conditions fostering both the perceptual grouping of the target and flanker and the recency and salience of the conflicting differences; conversely, by lessening such grouping and salience, prolonged training decreases or nullifies the interference.
Variation in stop releases in American English spontaneous speech.
Authors: Davidson Lisa
Published: October 2010

This study extends previous examinations of pre-consonantal stop releases in American English by investigating spontaneous speech from the National Public Radio’s StoryCorps project. Previous research has shown that in read speech, English speakers do not release stops in pre-stop and pre-pausal environments between 50 and 60% of the time. In spontaneous speech from more than 10 speakers, stops before obstruents and nasals in word-internal position (e.g., doctor, act), across a word boundary (e.g., pack these), or at the end of a phrase are produced without an acoustic release 62% of the time, while 29% of stops are released and 8% are deleted altogether. The only position in which there are more released stops than unreleased ones is in pre-pausal position (59.2% vs 38.8%). Deletion only occurs for coronals /t/ and /d/, which constitute 75% of the stops in the corpus. Stops are most likely to be unreleased before other stops (86%); before fricatives they are divided between being unreleased (53.7%), released (25.4%), and deleted (20.9%). The status of stop releases in English will be discussed with respect to articulatory coordination, aerodynamics, and stylistic uses by individual speakers. [Research supported by NSF.]
Comparison of acoustic characteristics of American English tense and lax vowels in maternal speech to prelingually deaf infants, normal-hearing infants, and adults.
Authors: Kondaurova Maria V. , Bergeson Tonya R. , Dilley Laura
Published: October 2010

Recent studies have demonstrated that mothers exaggerate phonetic properties of infant-directed (ID) speech. However, these studies focused on a single acoustic dimension, i.e., frequency, whereas speech sounds are composed of multiple acoustic cues. Moreover, little is known how mothers adjust phonetic properties of speech to children with hearing loss. This study examined the mothers’ production of frequency and duration cues to the American English tense/lax vowel contrast in speech to profoundly deaf (N = 12) and normal-hearing (N = 12) infants and to an adult experimenter. First and second formant frequencies and vowel duration of tense ([i, [u]) and lax ([i], [u]) vowels were measured. Results demonstrated that mothers exaggerated vowel duration in ID relative to adult-directed speech. However, only a trend suggesting an exaggeration of vowel space in ID speech was observed. These findings suggest that although both spectral and duration cues to the tense/lax distinction are modified in a systematic way in ID speech, vowel duration is exaggerated to a greater extent relative to spectral properties. Future analysis will include larger groups of hearing-impaired and normal-hearing infants to identify effects of hearing loss on the relationship between segmental and prosodic characteristics in ID speech.
A summary of filtering approaches in ocean acoustics.
Authors: Yardim Caglar , Michalopoulou Zoi-Heleni , Gerstoft Peter
Published: October 2010

Sequential filtering provides an optimal framework for estimating and updating the unknown parameters of a system as data become available. Filtering is a powerful estimation tool, employing prediction from previous es-timates and updates stemming from physical and statistical models that relate acoustic measurements to the unknown parameters. The foundations of sequential Bayesian filtering with emphasis on practical issues are presented covering both Kalman and particle filter approaches. Extended, unscented, and ensemble Kalman filters are compared to particle filtering approaches such as sequential importance resampling and advanced variants. Complex problems in ocean acoustics, where the state vector order is uncertain or the most suitable physical model for the problem at hand is not known a priori, are also addressed. Examples of model order selection and multiple model particle filters in underwater acoustic applications are given. Ocean acoustic examples are presented in target tracking, wave estimation, geoacoustic inversion, and frequency tracking.
On time-dependent properties of room responses to characterize scattering and diffusion.
Authors: Botts Jonathan , D’Antonio Peter , Xiang Ning
Published: October 2010

The process of diffusing or mixing sound in a room is of both theoretical and practical significance in room-acoustics. Simplified statistical models are often used to describe its overall behavior, but these models are not valid in general, especially in the early part of a room response. The geometry and scattering properties of the room determine the sound field and affect the validity of statistical assumptions. Several authors have proposed a theoretical time when the field can be considered sufficiently mixed or homogeneous, the transition between discrete reflections and the reverberant field. Since the time-evolution of the room response is dictated by the room, estimation of this time limit and other temporal characteristics affords the extraction of geometrical and scattering properties from a measured room impulse response. This paper investigates time-dependent properties of measured room impulse responses in order to characterize the scattering properties of rooms.
Hello?…Hello? Is anyone out there?
Authors: Bradley David
Published: October 2010

(Or Shallow Water: The changing acoustic environment and potential impact on aquatic life communication) The presumption is that marine life has inhabited shallow seas and consequently adapted to the peculiarities of that environment. Anthropogenic change is the focus of this discussion in the context of both ambient noise and propagation. Commercial and recreational activities span a wide range of frequencies, areal extent, and exposure times, and their consequences are described with reference to the acoustic environment in the absence of this activity. The continuing change, both predictive and speculative, will be discussed with regard to aquatic life acoustic behavior.
Bottlenose dolphin short-range communication in a shallow, noisy environment.
Authors: Jensen Frants , Beedholm Kristian , Wahlberg Magnus , Bejder Lars , Madsen Peter T.
Published: October 2010

Bottlenose dolphins use frequency-modulated whistles to convey information to conspecifics. The detection range of a signal depends on the source and receiver properties, the background noise level, and the sound propagation characteristics of the environment. The probability of detecting a signal can be modeled if these variables are known. Here we measured source levels and propagation loss of whistles from bottlenose dolphins in a shallow-water environment with high ambient noise levels dominated by snapping shrimp. A dispersed array of GPS-synchronized hydrophones was used to record whistles. Signals were localized acoustically using time-of-arrival differences of the same whistle derived by cross-correlating each channel with one recorded instance of the whistle, suitably filtered with a time-varying filter matching the fundamental time-frequency contour. Acoustic localization allowed for calculation of source levels and spectral content. Subsequently, background noise levels were measured and environmental sound propagation characteristics quantified using transmission experiments with pure tones and sweeps. Using the passive sonar equation, the active space of whistles in this habitat was estimated around 640–1150 m depending on whistle type, indicating that the effective communication range of dolphins in this habitat is an order of magnitude below previous estimates. Acoustic and ecological perspectives of these conclusions are discussed.
Passive classification of marine mammal vocalizations using an automatic aural classifier.
Authors: Hines Paul C. , Ward Carolyn M.
Published: October 2010

Passive sonar systems are often used to detect marine mammal vocalizations in order to localize and track them. However, classifying the genus or species is often required and this typically requires expertise not readily available on the vessel. Perceptual signal features, similar to those employed in the human auditory system, have been used to reduce false alarms in active sonar by automatically discriminating between target and clutter echoes. Many of the features were inspired by research directed at discriminating the timbre of different musical instruments — a passive classification problem — which suggests it might be applied to classify marine mammal vocalizations. To test this hypothesis, the automatic aural classifier was trained and tested on a set of marine mammal vocalizations from four species: the northern right whale, sperm whale, humpback whale, and bowhead whale. This paper will provide an overview of the aural classifier’s architecture, describe the data set, and present some preliminary classification results.
The need of collective expertise in noise control.
Authors: Brigitte Schulte-Fortkamp
Published: October 2010

An effective and sustainable reduction of highly annoyed people caused by noise is only possible with further scientific endeavors in the area of methods development and research of noise effects. Soundscape suggests exploring noise in its complexity, its ambivalence, and its approach toward sound to consider the conditions and purposes of its production, perception, and evaluation, to understand evaluation of noise as a holistic approach. To bring soundscape into the area of community noise research means to focus on the meaning of sounds and its implicit assessments to contribute to the understanding that the evaluation through perceptual effects is a key issue. So-called perception maps can provide meaningful information based on the local expertise. Local expertise in soundscape is a combination of meaningful knowledge about an area referring to the context of interactivity. The process of combining the data and analyzing them in a triangulation procedure will lead to the needed decisions. Within the soundscape approach, the strategy of triangulation will provide the theoretical frame with regard to the solution of, e.g., the change in an area.
An introduction to the physiological, psychological, and modeling aspects of the binaural display.
Authors: Joris Philip X. , Kohlrausch Armin
Published: October 2010

Binaural hearing is a model system to understand behavioral outcomes through models based on physiological measurements. Internal or compensating delays are one component that is generally present in binaural models. These delays are typically modeled as a continuum of pure time delays. We will review the physiological evidence for the distribution of these delays in different mammals, their (in)dependence on stimulus parameters, and we will briefly address their possible origin. Besides in physiology, the binaural display also plays a central role in describing psychoacoustic data. In a typical model of binaural processing, the binaural display is an intermediate stage in which activity is represented as a function of the internal interaural delay, computed by a cross-correlation process, and frequency. Such models have been applied successfully to a variety of lateralization experiments and to a great variety of binaural signal detection conditions. Besides introducing these elements of binaural models, we will also shortly address the question of whether there is a strict need for behavioral models to contain a continuous internal delay axis.
Binaural displays based on interaural phase compensation.
Authors: Marquardt Torsten
Published: October 2010

The asymmetry of many neural tuning curves to the interaural time delay (ITD) of wideband stimuli around their maximum implies that such external temporal differences are compensated by some internal phase-delay mechanism rather than a system of axonal time delays. An internal phase delay explains why the ITD that generates maximum neural activity (best delay) is generally less than a half period of the tuning curve’s modulation (“π-limit”). The interaural phase circle (IPD circle) and the smoothed interaural phase spectrum (SIPS) are new binaural displays, which are based on these physiological findings. The IPD-circle displays interaural phase difference (IPD) and interaural phase coherence (IPC) of single frequency channels in a polar diagram as vector angle and magnitude, respectively. Its two-dimensionality facilitates the study of IPD and IPC fluctuations. The SIPS shows an activation matrix of binaural coincidence detectors across their best frequencies and internal phase delays. It serves similarly to the traditional cross-correlogram as a display of interaural temporal differences across frequency. Its computation is based on the interaural phase spectrum, which is smoothed in frequency-dimension by the auditory filter shapes. These displays describe neural ITD tuning curves with their asymmetry, and could provide a basis for future physiologically orientated models.
Contextual influences on the excursion size of fundamental frequency in infant babbling: A comparative study of English and Mandarin.
Authors: Yang Jie , Davis Barbara
Published: October 2010

Davis and MacNeilage (1995) reported contextual influences on infants’ segmental production in which vowel production preference and error were strongly influenced by word level contexts. However, few studies have addressed the issue of contextual influences on supra-segmental production in pre-linguistic periods of acquisition. The present study investigated the influence of utterance length and utterance position on the size of f0 excursion in the babbling of English and Mandarin infants. Spontaneous babbling speech of four monolingual English infants and four monolingual Mandarin infants at the age of 8 and 14 months were collected. Canonical babbling syllables with either a falling or rising f0 contour were acoustically analyzed. The magnitude of f0 excursion size was calculated as the difference between maximum f0 and minimum f0 within a syllable. Results showed that F0 excursion size was significantly larger in monosyllables than in individual syllables of multisyllabic utterances. It is also larger in utterance final syllables than in non-final syllables. The influence of age and ambient language properties of f0 will also be discussed. [Work supported by NSF 0844080.]
Effects of perceived age on prosodic judgments of child and adult speech.
Authors: Dilley Laura C. , Redford Melissa A. , Millett Amanda , Wieland Elizabeth
Published: October 2010

Speakers’ ability to effectively use prosody (e.g., pitch and timing) to convey information improves over developmental time. This research investigated effects of perceived talker age on subjective prosody judgments, which are often central to developmental prosody research. Speech was subjected to modification in which formants and fundamental frequency were lowered, for 5-year-old children, or raised, for adult caregivers. The manipulations were expected to affect talkers’ perceived ages, while leaving critical acoustic-prosodic correlates intact (e.g., fundamental frequency contour, speech rate). In experiment 1, eight analysts used a prosodic labeling system to indicate phrasal boundaries and disfluencies in unaltered and spectrally modified speech. In experiment 2, listeners rated unaltered and spectrally modified speech regarding rate, fluency, and estimated age. Preliminary data revealed that the manipulation caused children and adults to be judged older or younger, respectively, as expected. Importantly, the manipulation affected ratings of rate and fluency (experiment 2), but not rates with which analysts identified phrasal boundaries or disfluencies (experiment 1). Results suggest that prosodic labeling systems may provide more reliable means of studying prosody than ratings, due to reduced effects of confounding speaker characteristics (e.g., perceived age) on judgments, a finding with implications for studying speech development. [Work funded by NIH-NICHD grant 1R01HD061458-01.]
Tone recognition of the two checked tones in Taiwanese.
Authors: Kuo Grace
Published: October 2010

The present study uses the gating paradigm to investigate the processing of the checked tones in Taiwanese. Taiwanese checked tones are the tones in syllables ending in stops /p, t, k, ʔ/. In terms of tone value, there are two kinds, high falling (e.g., kut5 “slippery”) and mid falling (e.g., kut3 “bone”). The two checked tones are each other’s sandhi tone and since both of them are so short in duration that some people claim that they are under a merging process. Therefore, gating, a paradigm that provides us with precise control of processing details, is used to show that the two checked tones are distinguishable in processing. Stimuli are CaC syllables spoken in isolation (ISO) and taken from four different boundary positions: IP-initial, tone-group-initial, word-initial, and syllable-initial. In the gating task, the initial consonant of each syllable forms the first gate, and the subsequent gates are constructed with 40 ms increments. The subjects are asked to identify the tone for each gated stimulus and give a confidence rating for the judgment.
Patterns of tone sandhi productivity in Tianjin Chinese.
Authors: Zhang Jie , Liu Jiang
Published: October 2010

In Tianjin Chinese, three of its four lexical tones (L, H, LH, HL) undergo tone sandhi on the initial syllable of disyllabic words: L becomes LH before L, LH becomes H before LH and L before H and HL, and HL becomes H before L and L before HL. This study provides a detailed acoustic description of tone sandhi patterns in both real lexical items and nonce words in Tianjin Chinese. The data were collected from 48 speakers in Tianjin, who were instructed to pronounce disyllabic sequences as real words based on voice prompts. The results showed that in real words, contra traditional descriptions, the sandhis are non-neutralizing and variable; in nonce words, the productivity of the sandhis as compared to that in real words also varies depending on the sandhi—some are less productive (e.g., LH→H/ __LH), some are comparable (e.g., LH→L/__HL), and some are more productive (e.g., HL→H/__L), indicating a combination of underlearning, proper learning, and overlearning of the sandhis from the lexicon. A theoretical model that predicts the productivity patterns based on the phonetic properties of the sandhis and statistical generalizations about the sandhis over the lexicon will be discussed.
Contrastive breathiness on consonants and vowels.
Authors: Esposito Christina M. , Khan Sameer ud Dowla
Published: October 2010

While numerous languages exhibit contrastive breathy phonation either on consonants (e.g., Indic languages) or on vowels (e.g., Zapotec languages); very few languages preserve this contrast across both consonants and vowels. Two such languages are Gujarati and White Hmong. Given that breathiness on consonants is typically realized as a breathy-voiced release into the following vowel, how are the two types of breathiness distinguished in CV sequences, if at all? We examine acoustic and electroglottographic data collected from speakers of Gujarati and White Hmong to determine what properties reliably distinguish breathy and modal voice in potentially ambiguous CV sequences, and to explore the phonetic and phonological properties shared between these two genetically unrelated languages. Preliminary results from both languages are strikingly similar; modal vowels adjacent to breathy consonant releases strongly resemble phonemically breathy vowels, and only the exact timing and magnitude of the acoustic reflexes of breathiness phonetically distinguish the two sequences. Phonological evidence in the form of distributional constraints, however, can aid listeners of both languages in determining the source of breathiness: both languages prohibit the co-occurrence of breathy consonants and breathy vowels, and in White Hmong, tonal cues can also reveal the underlying phonation of an ambiguous CV sequence.
Intonation in Tongan.
Authors: Vicenik Chad J. , Kuo Grace
Published: October 2010

This paper presents a model of the intonational system of Tongan, an Austronesian language, taking the autosegmental-metrical theory as its framework. Tongan has lexical stress which appears on the penultimate syllable of prosodic words and is marked post-lexically with one of two bitonal pitch accents—a rise, LH*, or a low-fall, ML*. Measurements show that the first tone of both pitch accents aligns with the stressed syllable onset, while the second tone aligns with the stressed syllable offset. There is evidence for two tonally marked levels of prosodic phrasing in Tongan, the intonational phrase (IP) and the accentual phrase (AP). The IP is about the size of a full utterance or major phrase and is marked by a final boundary tone and are realized on the IP-final syllable. Five boundary tones have been observed. The smaller unit, the AP, usually contains one lexical word plus preceding functional elements. Three AP-final tones have been observed, realized on the final syllable of the phrase. Lastly, focus is only realized intonationally through increased pitch range on the focused element. Tongan is typologically interesting because it provides another case in a growing list of languages that intonationally marks both head and edge prominence.
Can musical aptitude and experience predict success in non-native tone word learning?
Authors: Cooper Angela , Wang Yue
Published: October 2010

Non-native linguistic pitch perception is subject to influence from a variety of factors in addition to linguistic background, including musical experience. The present study investigated the effects of musical aptitude and musical experience on Cantonese tone word learning and how these musical factors interact with linguistic experience. Adult native Thai listeners whose native language (L1) is tonal and English listeners with a non-tonal L1, subdivided into musician and non-musician groups, engaged in a seven-session perceptual training program, learning the meanings of 15 novel vocabulary words distinguished by five Cantonese lexical tones. Before training, a musical aptitude task was administered to establish the participants’ level of musicality and auditory discrimination skills. The results show significant group differences in tone word learning proficiency by the end of training. English musicians outperformed their non-musician counterparts; however, the Thai musicians were not significantly different from the Thai non-musicians. Results from regression analyzes further show that higher musical aptitude scores predicted tone word learning success for the English group but not for the Thai group. These findings suggest that the influence of musical experience in constructing novel lexical representations of tone words differs as a function of linguistic background.
Propagation models in the ocean acoustic field with hard soil.
Authors: Quino Cerdan Juan Manuel , Nñez Guardado M. , Ruíz Rodríguez Jorge
Published: October 2010

This paper addresses the human interest for lossless data transmission by water sound waves, knowing that electromagnetic waves dramatically attenuate in sea water. A normal mode method is employed in order to determine varying frequency propagating modes and waveguide height to observe individual mode contribution. It considers a shallow water waveguide between the hard soil (sand) and the sea surface. Transmitter and receiver will be several kilometers away from each other, and the future intended applications include object detection and submarine communication.
Acoustic propagation in a river channel environment.
Authors: Frank Scott D.
Published: October 2010

Acoustic propagation modeling in river environments would take advantage of available environmental data and be relevant to recent work regarding passive threat detection. Normal mode and ray methods will be applied to 3-D geometric channels in order to investigate propagation characteristics such as convergence zones, cutoff frequencies, and transmission losses. Calculations for these types of environments must also account for 3-D propagation effects including vertical and horizontal reflections, shallow bottoms, and sloping boundaries. Preliminary ray path results can be used to compare propagation behavior in ideal and fluid bottom linear waveguides with potential for incorporation of monitoring data and possible application to meandering river channels.
Parabolic equation solutions with increased capabilities for layered poro-elastic media.
Authors: Metzler Adam M. , Siegmann William L.
Published: October 2010

Parabolic equation solutions have recently been improved to increase accuracy for range-dependent problems involving sloping fluid-solid interfaces. One improvement is a formulation using a new set of variables that includes a term proportional to the normal stress at a horizontal interface [J. Acoust. Soc. Am. 127, 1962 (2010)]. These variables lead to horizontal interface conditions with only first-order derivatives, which is valuable for implementing techniques such as energy conservation or single scattering that handle range dependence. This improvement is extended to problems that involve layered poro-elastic media that occur in shallow water environments. An analogous formulation is derived for the field variables in a poro-elastic layer. The horizontal interface conditions have similar characteristics as in the elastic case. Solutions are obtained for layered environments and are benchmarked to confirm accuracy. [Work supported by the ONR.]
On the in situ measurement of acoustic impedance of the surfaces of a real room by an inverse optimization acoustical approach.
Authors: Pablo Nava Gabriel , Yasuda Yosuke , Sato Yoichi , Sakamoto Shinichi , Hirata Keiji
Published: October 2010

As numerical simulations of large-scale complex-shape sound fields have become affordable by powerful computers and algorithms, there is an increasing interest on new methods of in situ assessment of acoustic impedance and absorption coefficients to yield accurate sound predictions. Among the existent approaches, those based on inverse boundary frameworks offer the advantage of dealing with surfaces of arbitrary shapes. Moreover, estimation of the acoustic impedance of not one but all the surfaces in an interior using one microphone has been demonstrated. A drawback of these frameworks is a high sensitivity to noise due to a rank deficient inverse model. The authors have previously introduced an iterative optimization method that avoids the direct solution of such ill-conditioned model by exploiting prior knowledge of the surface geometry. Numerical simulations suggest that the proposed approach improves the signal-to-noise ratio, which motivated preliminary experiments in a reverberation chamber. This report presents experimental data of a new attempt to estimate the acoustic impedance on the (interchangeable) surfaces of a real room. The results were further investigated by creating a novel surface configuration and contrasting both sound fields, that of the real room and the predicted one (using the estimated impedance values).
Outdoor sound power calibration of reference sound sources.
Authors: Campanella Angelo J.
Published: October 2010

Methods and procedures for outdoor sound power measurement for reference sound sources according to ISO 6926/ANSI 12.5 are discussed. This method assures no low-frequency cutoff of the sound power determination. A quiet outdoor site with a sealed surface of suitable radius, clear of structures and trees is required. Measurement plan-positions are marked on the surface. Equipment components are prepared in advance for efficient deployment. Weather forecasts are used to determine day or night measurement periods that are free of rain and wind. When ready, site barometric pressure, dry bulb temperature, and wet bulb temperature are measured. The microphone height and the 2 m radius are positioned with a fixture. Sound pressure level data are acquired at all microphone positions, serially if necessary. Sound power results are corrected to standard conditions. High-frequency results are corrected for humidity as it affects sound absorption by air. Results obtained over several years and at a variety of temperatures are discussed.
Acoustic performance of an installed real-time three-dimensional audio system.
Authors: Faller Kenneth J. , Rizzi Stephen A. , Schiller Noah , Cabell Randolph H. , Klos Jacob , Chapin William L. , Surucu Fahri
Published: October 2010

The Exterior Effects Room (EER), located at the NASA Langley Research Center, is a facility built for psychoacoustic studies of aircraft community noise. Recently, the EER was significantly upgraded to allow for simulation of aircraft flyovers in a 3-D audio and visual environment. The upgrade included installation of 27 satellite and 4 subwoofer loudspeakers that are driven by a real-time audio server. The audio server employs an implementation of the vector base amplitude panning method to position virtual sources at arbitrary azimuth and elevation angles in the EER. Real-time application of filters, time delays, and gains are required to compensate for installation effects, including those associated with the irregular room geometry, colorization due to varying loudspeaker installations, and crossover filtering. The authors previously showed [J. Acoust. Soc. Am., 127, 1969 (2010)] that color compensation and crossover filtering could be achieved for satellite and subwoofer loudspeakers. However, the resulting FIR filters were too long (32 768 taps) to implement in real-time. The focus of this work is on the development of reduced-length surrogate IIR filters and on the measurement of the acoustic performance of the installed real-time system.
Humpback whale song on the Western Antarctic Peninsula feeding ground.
Authors: Stimpert Alison , Nowacek Douglas , Friedlaender Ari , Peavey Lindsey
Published: October 2010

Humpback whale song is a complex and highly stereotyped acoustic display believed to be associated with breeding activities. The song has primarily been recorded from male whales on the low-latitude breeding grounds, though singing has also been documented on some feeding grounds during late fall and early spring using stationary passive acoustic recorders. Here, the song was documented with animal-bourne tags in a relatively unstudied population of humpback whales along the Western Antarctic Peninsula feeding ground during late fall (May and June). DTAGs were attached for 24-h periods to six whales in 2009 and eight whales in 2010 to record sound production and body orientation. Song chorusing has been present on all tag acoustic records analyzed to date, and multiple whales tagged in 2010 were actively singing. Song bouts in the 2010 records were generally less than one dive cycle in duration and were often surrounded by periods of social sound production. This is the first description of humpback whale song in the Antarctic, and its frequent occurrence is indicative of the amount of social activity on this feeding ground. These data suggest that humpback whale mating cycles may be more driven by season than by physical location.
Spatial and temporal patterns of dolphin distribution and relative abundance on the West Florida Shelf based on autonomous acoustic recorder detections and visual survey data.
Authors: Simard Peter , Wall Carrie C. , Zeddies David G. , Frankel Adam S. , Gowans Shannon , Allen Jason , Wells Randall S. , Mann David A.
Published: October 2010

Determining the abundance, movements, and distribution of animals can be accomplished using a variety of methods. Here we use boat-based visual surveys and detection of sounds with autonomous acoustic recorders to determine the presence of dolphins in the coastal waters of the West Florida Shelf in the eastern Gulf of Mexico. The autonomous acoustic array consisted of 12 bottom-mounted digital spectrogram (DSG) recorders deployed from June to September 2008. Whistles and echolocation trains were identified in spectrograms for each recorder. Mean active space of each recorder was determined using the Bellhop propagation model with inputs appropriate for the location, including bathymetry, frequency, bottom loss, sound velocity profiles, and weather conditions. Acoustic detections per km2 per hour were calculated for each recorder. Visual surveys spatially overlapped the acoustic array from June to August 2008. Visual detections were analyzed per unit effort in grid cells overlaying the DSG locations. The overall relative abundance of dolphin acoustic detections in recorder active spaces and visual detections in corresponding grid cells are compared. In addition, spatial and temporal patterns of the acoustic presence of dolphins are discerned from the continuous time series of acoustic recordings.
Interaural differences in the bottlenose dolphin (Tursiops truncatus) auditory nerve response to jawphone stimuli.
Authors: Mulsow Jason
Published: October 2010

Suction cup transducers, also known as “jawphones,” are a common means of delivering acoustic stimuli to odontocete cetaceans during auditory evoked potential hearing studies. However, the differences in auditory stimulation at the ears ipsilateral and contralateral to the jawphone are not well understood. To examine these differences, bottlenose dolphin auditory nerve responses (ANRs) were simultaneously recorded from both ears following stimulation by a jawphone placed on the sound reception area of the lower jaw. The amplitudes and latencies of ANRs were measured as functions of stimulus level and used to estimate the differences in received level and time of arrival between the two ears. Results indicated that a broadband click received at the ear contralateral to the jawphone was attenuated by 18 dB relative to the level at the ipsilateral ear. The latency of the ANR from the contralateral ear was delayed by 180 μs relative to the ipsilateral ear ANR. This arose from the combination of an 88 μs interaural acoustic delay and a 92 μs increase in the latency of the contralateral ANR due to the relatively attenuated received level. The relevance of these results to future hearing studies using jawphones will be discussed. [Work supported by ONR.]
Continuous vigilance by echolocating bottlenose dolphins (Tursiops truncatus) for up to fourteen days.
Authors: Branstetter Brian K. , Finneran James J. , Ridgway Sam H.
Published: October 2010

The dolphin’s ability to actively detect randomly presented targets via echolocation for three, continuous, 5-day sessions and a single 14-day session was investigated. During each experimental session, a dolphin was required to ensonify the perimeter of its floating enclosure and report the presence of phantom echo generated (PEG) targets by pressing a response paddle. PEG targets were generated by convolving the dolphin’s echolocation signal with the impulse response from a metallic sphere. The resulting PEG target was delayed in time and projected back to the dolphin to simulate the echo of a “real target.” PEG targets varied in simulated range, location, and time of occurrence. Percent correct for target detection were 97, 99, and 100 for dolphin A and 75, 78, and 86 for dolphin B, during each 5-day session, respectively. During a 14-day session, dolphin A reported 98% of the targets correctly. False alarm rates were low and there was no significant effect of range or inter-trial-interval on percent correct or response time. The results indicate that dolphins are capable of continuously monitoring their environment via echolocation for multiple days (at least 14 days) and can accurately report the presence of regularly occurring targets.
A method for estimating the orientation of a directional sound source: Application to the trawling bat N. leporinus.
Authors: Guarato Francesco , Hallam John , Uebernickel Kirstin
Published: October 2010

Modeling the behavior of bats when performing hunting tasks should take into account behavioral features such as head orientation when a call is produced. Estimating head orientation using remote acoustic recordings can be generalized to estimating the pose of any directional sound source producing a broadband signal in the ultrasonic range. Provided that microphone recordings, from known microphone positions, of the calls produced by the source are available and that source directivity is known, a mathematical method can be built up for estimating source orientation by looking for the best match between all possible source orientations and the true one using a comparison of recorded data, with values calculated from knowledge of source directivity and microphone positions with respect to source. Such a method has been tested in a laboratory environment with a Polaroid transducer as the source. Experiments show that the method estimates orientations very close to the true ones and point out the limits within which the method guarantees good performance and why. The same estimation method has been applied to calls emitted by the trawling bat N. leporinus performing hunting tasks.
Second-language experience and speech-in-noise recognition: The role of talker-listener accent similarity.
Authors: Pinet Melanie , Iverson Paul , Huckvale Mark
Published: October 2010

There is a clear interaction between native and non-native accents in speech-in-noise recognition, with listeners being better at accents that match their own speech. This study investigated how this talker-listener interaction is modulated by L2 experience and accent similarity. L1 southern British English (SE) and L1 French listeners with varying L2 English experience (inexperienced, FI; experienced, FE; and bilinguals, FB) were tested on the recognition of English sentences mixed in speech-shaped noise that were spoken with a range of accents (SE, FE, FI, Northern Irish, and Korean-accented English). The results demonstrated that FI listeners were more accurate with FI talkers and showed graded sensitivity for all accents. The SE listeners, however, had their recognition processes selectively tuned to their own accent. FE and FB listeners were more similar to SE listeners as their L2 experience increased. In order to account for this interaction, an accent similarity metric was applied to the talkers’ and listeners’ speech. The results demonstrated that there were significant correlations between speech-in-noise recognition and the acoustic similarity of the talkers’ and listeners’ accents. Overall, the results suggest that L2 experience affects talker-listener accent interactions, altering both the intelligibility of different accents and the selectivity of accent processing.
Influence of talker-specific information on recognition memory for accented speech.
Authors: Miller Rachel M. , Sanchez Kauyumari , Rosenblum Lawrence D. , Dias James W.
Published: October 2010

Talker-specific (idiolectic) information aids memory for words repeated in the same voice. [Palmeri et al., J. Exp. Psychol. Learn. Mem. Cogn. 19, 2 (1993).] However, there is some evidence that the influence of idiolect on the perception of accented speech occurs differently. The current studies tested the impact of talker and accent change on memory for words using a continuous recognition memory task. Native English listeners were presented with accented words which were later repeated in the same or in a different voice. Subjects were asked to identify if the words were old (previously presented) or new (never presented). Memory performance was measured in terms of reaction time and recognition accuracy. In experiment 1, words were repeated in the same or in a different voice across repetitions, with the voices sharing an accent. Preliminary results suggest that hearing the words in the same voice improves recognition memory for accented words. In experiment 2, differenct voice repetitions represented models from the same or a different accent background. Listeners were asked to identify old words as being produced in the same or a different voice. Initial results indicate that hearing repetitions in the same accent improves recognition memory, but interferes with voice identification.