bluuebunny/crossref_metadata_2025 huggingface dataset:
Bamboo pipe wall vibrations in Asian free reed instruments
Authors: Faaborg Miles , Cottingham James
Published: April 2012

Asian free reed instruments generally employ bamboo pipes, and the properties of bamboo are of current interest, especially in relation to pipe wall vibrations. Recent results on measured physical properties of bamboo as used in Asian free reed instruments are presented, including mechanical properties of bamboo reeds as well as pipes. Recent investigations have been made of wall vibrations in the bamboo pipes of free-reed mouth organs for mechanically excited pipes. Modal frequencies and mode shapes of a number of pipes were measured, and measurements of pipe input impedance were made, some of which suggested possible changes occurring as a result of damping the pipe vibrations [Cottingham, J. Acoust. Soc. Am. 114: 2348 (2010)]. The most recent work involves the study of pipe wall vibrations for a mechanically blown reed-pipe combination. This was done for undamped pipes and pipes heavily damped with sand or other damping material. Measurements were made of the internal and external sound fields as well as measurements of the wall vibrations. [Work partially supported by US National Science Foundation REU Grant PHY-1004860.]
Comparison of the insertion loss of diffusive noise barriers using scale model experiments
Authors: Haan Chan Hoon , Lee Jung youn
Published: April 2012

A new design of an environmental friendly noise barrier was suggested which can be assembled by unit blocks. It was anticipated to decrease of noise levels because the shape of the blocks is so diffusive that it may reflect and diffuse the sound. The unit blocks also contain the soil and vegetation for landscape which can contribute the noise control as well. Four different designs of noise barriers were suggested considering various practical conditions of construction. In order to investigate the acoustical performances of the various diffusive noise barriers, different size of unit block including 30, 25, 20 and 15cm were introduced. 1/10 scaled models were made and the insertion loss of each model was measured in an anechoic chamber. Also, the difference of diffusive and flat surfaces of noise barriers was analyzed. As a result, it was found that there is no difference of insertion losses depend on the distance from the noise barriers. It was also revealed that the diffusive noise barriers have larger insertion loss than flat noise barriers. And the bigger the unit block is, the larger noise insertion losses were acquired.
An experimental and numerical investigation of the sound distribution in street canyons with non-parallel building façades
Authors: Piippo Kaj Erik , Tang Shiu-keung
Published: April 2012

In this paper the sound distribution in a street canyon is investigated both experimentally and numerically. The sound field inside a 1:4 scaled down model of a street canyon has been investigated. A line source was used as sound source in order to generate steady cylindrical wave propagation. The sound distribution on the façades were mapped in the frequency domain and previously presented as contour plots. In order to validate the measurements, two-dimensional numerical simulations were conducted using COMSOL Multiphysics software, which uses a finite element approximation method. A cross-section at the centre of the scale model was chosen to be compared with the 2D simulation results. The comparison showed reasonable agreement, especially for frequencies starting at 1000Hz and up. The experimental data was expressed in 1/24 octave band frequency, while the simulated data was a single narrowband frequency. In order to get a better agreement for frequencies below 1000Hz more simulated data has been generated and is presented in this paper. Furthermore, initial results of 3D simulations are presented, as well as the impulse response of the street canyon model.
The relationship between different measurement methods of testing tire noise
Authors: Zuoteng Shi
Published: April 2012

With the increasing demands on the noise, the noise of vehicles has become a problem to which the auto -industry attaches great importance. Tire noise measurement constitutes a major part in vehicles noise measurement. To measure tire noise, traditionally there are 3 way to accomplish it: Pass-by noise method, Trailer Method, Laboratory Drum Method. The measure result depends on different contact surface and different tire tread pattern. Different measurement method shows different result. To find out the relationship between different tire measurement method can not only save tire noise measurement expense, but also enhance the data conviction. The paper runs a huge amount of experiments by each tire noise measurement method to compare the difference and adopts analogy of material, force, and acoustic fully analyzing the relationship of different measurement methods.
Compatibility of traffic noise planning control and land use in intensive city
Authors: Zhang Weichen , Zhu Wenying , Zhou Yude
Published: April 2012

The optimal way to solve traffic noise pollution is the planning-control. But it is a problem that how to get a perfect balance between the control distance and the land use, especially in some intensive City, such as Shanghai, Hong Kong etc. This article intends to put forward some exploratory ideas about the distance control with the study on the sound field of urban traffic noise distribution. Different from Euro and USA, The traffic noise is a serious problem in most Asia City. At present, these governments limited the distance along the traffic roads to reduce the noise level, yet it restricted the land-use. We plans to sketch a 3D view spatial pattern different from the past horizontal sound field research. And then; we should propose a constructive restriction on the sensitive buildings along the distinct roads, such as the layout/height of the front and back buildings. This paper proposes a new idea about the planning space control along the traffic roads, and put forward different control requirements for sensitive buildings on heights/distance. It will be applied to solve the traffic noise of intensive cities, and promoted the harmoniously progress between cities' planning and land use.
The research of resonance frequency influence by 1/20 scale model test
Authors: Zhu Xiangdong , Yan Xiang , Xue Xiaoyan , Jia Hexiang
Published: April 2012

Acoustical enclosed workshops are used in high-level noise machine, especially for natural gas compressor. By this method the noise source was closed in workshop. Combined with sound absorption construction can decrease the noise level can be decreased out of workshop. But these kinds of methods have disadvantages. The low frequency noise levels of this type machine are higher than other machine, especially of infrasonic sound. The typical shape of workshop is rectangular and their sizes are about ten by ten meters. So the resonance frequencies are coincidence with the noise frequency of machine. All of these lead to the “sound box effect”, which means low frequency and infrasonic sound will be amplified. The test data of practical cases in China indicate that these methods can be increase the pollution of infrasonic sound. In this study, we test the resonance frequency of a 1/20 scale model. In order to find out what the influence of noise control issue.
A FEM formulation for sound propagation over porous materials
Authors: Hong Hyun , Lau Siu-Kit , Li Kai Ming
Published: April 2012

It is well known that the propagation of sound is sensitive to the acoustical properties and thicknesses of the porous materials when the source is placed near them. An efficient yet accurate numerical scheme to compute the sound propagation over an extended reaction surface is needed for the prediction and control of environmental noise. The numerical scheme can also find its application in enclosed spaces with the installation of absorption materials on the reflecting walls. To meet these objectives, a finite element method (FEM) is explored in a pilot study for determining the sound field above a layered porous ground. The sound fields computed by the FEM formulation are compared with those calculated by exact analytical formulas due to a monopole source. Three types of porous materials: locally reacting materials, semi-infinite extended reaction materials, and extended reaction materials with an impedance backed layer, have been considered in the present study. It has been demonstrated that the FEM formulation provides an accurate numerical solutions for predicting the sound field above a flat porous ground.
High-frequency acoustic atomisation: do Faraday's results still apply?
Authors: Friend James , Yeo Leslie
Published: April 2012

Atomisation using high-frequency surface acoustic waves offers a revolutionary means to form monodisperse aerosols for nanoparticle fabrication and pulmonary drug and stem cell delivery. The underlying mechanism of atomisation is more complex than presented in the literature: rather than a simple parametric or subharmonic Faraday capillary wave mechanism which is physically impossible in this system, capillary waves form from a previously unknown mechanism that transforms the 10 to 1000 MHz excitation into broadband capillary waves around 10 kHz. Capillary waves of a particular most dangerous wavelength are driven to breakup and droplet formation. The new theory describes the droplet size with excellent accuracy, and fits experimentally peculiar behaviour obtained upon changing the viscosity and surface tension of the fluid to be atomised and the amplitude and frequency of the acoustic wave. In the presentation, genuine applications for the technology will be shown from our laboratory, in vitro, and animal in vivo studies followed by a thorough explanation of how the atomisation takes place including high-speed video of the phenomena of atomisation and details of our experiments and analyses.
Analysis on the audibility in directional differences of head-related transfer function magnitudes
Authors: Liu Yu , Xie Bosun , Yu Guangzheng
Published: April 2012

A head-related transfer function (HRTF) varies as a function of sound source directions. In a dynamic virtual auditory display (VAD) based on HRTF filtering, dynamic binaural synthesis requires HRTFs to be updated constantly to accommodate the transient virtual source direction relative to listener. A HRTFs set with appropriate directional resolution can generate smooth transition when switching between HRTFs, and at the same time, simplifies dynamic binaural synthesis. Based on the measured HRTFs from KEMAR mannequin and human subjects with supper high directional resolution, the directional difference in HRTF magnitude spctra, binaural loudness level spectra and interaural localization cues are analyzed in present work. Combined with the statistical results of psychoacoustic experiments, psychometric functions for directional discrimination of HRTF magnitudes are derived. Finally, in terms of resultant audibility in directional differences of HRTF magnitudes, the directional resolutions of HRTFs for dynamically synthesizing virtual source at various directions are suggested.
Efferent modulation of physiological and behavioral measures of cochlear mechanics
Authors: Dhar Sumitrajit , Zhao Wei , Dewey James
Published: April 2012

Efferent control of cochlear mechanics is of interest to scientists and clinicians alike. The functional roles of the descending auditory neural pathway in various species is being actively investigated by multiple groups around the world. Its role in the human is also of interest, with signs of efferent involvement in attention, learning, protection from noise, and signal detection in noise. The final leg of the auditory efferent pathway extends from the superior olivary complex in the brainstem to the cochlea with direct termination of neurons of the medial branch on outer hair cells. Activation of the medial olivocochlear circuit alters outer hair cell gain thereby modulating cochlear mechanics. Otoacoustic emissions provide a convenient tool for probing the efferent pathway. We will present results of recent work by our group examining the modulation of otoacoustic emissions and behavioral hearing thresholds by the medial olivocochlear efferents. Results demonstrate a common mechanism driven by changes in both magnitude and phase in cochlear mechanics manifest in both otoacoustic emissions and behavioral thresholds. These findings have important implications for developing reliable tools for the quantification of efferent modulation of cochlear physiology for possible diagnostic and therapeutic purposes.
Suppression tuning of distortion product otoacoustic emissions in humans: results from cochlear mechanics simulation
Authors: Liu Yi-Wen , Neely Stephen T.
Published: April 2012

Is human hearing more sharply tuned than other mammals? This has been a heavily debated subject in the field of cochlear mechanics. The debate continues partially due to lack of non-invasive methods to estimate human cochlear tuning accurately. Recently, Gorga et al. (2011, JASA) derived tuning curves from suppression of distortion product (DP) otoacoustic emissions (OAEs) in normal-hearing human ears. Frequencies of the primary tones were varied from 0.5 to 8 kHz. Sharpness of tuning was analyzed in terms of the Q-value of equivalent rectangular bandwith, which ranged from 4 to 10 at the lowest stimulus level tested. The Q-values were similar to that of psychoacoustic tuning but lower than inferred from latencies of stimulus-frequency OAEs (Shera et al. 2002, PNAS). In the present work, we simulate DPOAE suppression based on a computer model of cochlear mechanics (Liu and Neely, 2010, JASA). The simulated DPOAE suppression tuning curves (STCs) resemble those obtained in experiments but discrepancies remain. At high frequencies, the simulated DPOAE STCs are not as sharply tuned as the magnitude response of traveling waves in the model. Confounding factors and interpretation of results will be discussed. (Supported by Taiwan's NSC and NTHU)
Fault diagnosis of railway roller bearing based on vibration analysis and information fusion
Authors: Chen Bin , Yan Zhaoli , Cheng Xiaobin , Liu Wei
Published: April 2012

Roller bearing is an important mechanical element of railway vehicle. It usually has defects in outer race, inner race or balls due to continuous metal-metal contacts in high-speed operating conditions. For the reason of impurity in lubricant oil, measuring locations and background noise, fault features extracted from vibration signal directly in time-domain or frequency-domain are unstable or uncertain, which may seriously affect the diagnosis accuracy. This paper presents a diagnostic method based on vibration analysis and information fusion. In the method, the signal analysis methods such as wavelet packet are processed to depress background noise of collected vibration signals. Considering that vibration energy at characteristic rotational frequency may increase with defect on a particular bearing element, they are extracted as fault feature vectors, which are used to train support vector data description (SVDD) classifiers. To reduce recognition uncertainty of single fault classifier, each classifier is regarded as independent evidence, and all evidences are aggregated by Dempster's combination rule. Experiment results show that the proposed algorithm can improve the diagnosis accuracy of roller bearing.
Design and experiment of a cradle truss type floating raft system
Authors: Feng Zhang , Zhenguo Bai , Xiaobin Liu , Mengsa Yu
Published: April 2012

In this paper, a new design concept of an isolated cradle trusslike structure to support vibrating machinery is proposed. The acoustic and vibratory energy transmission in this isolation system is investigated to improve the vibration isolation performance of conventional floating raft system. The finite element method and experimental measurements are used to understand the dynamic behavior of this cradle truss. In conjunction with experiments, a vectorial four pole parameter numerical model is used to identify power flow of the floating raft isolation system. The proposed floating raft design achieved a vibration reduction of 30–40dB in the frequency range of 20–600Hz. It is also shown that the loss factors of the cradle truss configured floating raft are up to 4dB than conventional floating flat raft.
Canadian raising and the perception of consonant voicing
Authors: Puderbaugh Rebekka , Nearey Terrance M.
Published: April 2012

Studies have shown that monophthongal VC sequences with higher F1 and shorter durations result in more [-voice] consonant responses than those with lower F1 and longer durations [Moreton, E. 2004 J. Phon. 32(1), 1, Nearey, T. M. 1997, J. Acoust. Soc. Amer., 101(6), 3241]. However, certain diphthongs in varieties of English with Canadian Raising show the opposite pattern, namely that before C[+voice], /aɪ/ diphthongs will have higher F1 in the nucleus than before C[-voice]. This study will investigate the interaction of interpretations of vowel tokens as monophthongs or diphthongs on the perception of the voicing of the following consonant. Measurements will be made from the speech of 10-20 speakers of Canadian English from the Edmonton area to be used in the resynthesis of hVd and hVt tokens. This will involve construction of a multi-dimensional continuum varying F1 values of the vowel nucleus as well as vowel duration and trajectory from nucleus to offglide. The resulting continuum will span both the four phonetic vowel categories [^, a, ^ɪ, aɪ] (where [^ɪ] and [aɪ] are viewed as allophones of a single phoneme /aɪ ), and also the final consonants /t/ and /d/.
Neural representations of vowels and vowel-like sounds
Authors: Carney Laurel H. , McDonough Joyce M.
Published: April 2012

Neural representations of speech at every level of the neuraxis have nonlinear features that are not described by spectrograms or linear filter-banks. In this study, recent computational models for populations of cells in the auditory periphery, brainstem, and midbrain were used to explore the implications of vowel features for neural responses. Peripheral neural responses are characterized by strong periodicities, dominant frequencies, that depend upon the distribution of energy across the harmonics and vary across vowels [Fant, 1970]. Strong periodicities related to the fundamental and low-frequency harmonics are observed for peripheral neurons tuned to a wide range of frequencies [Delgutte & Kiang, 1984]. The computational model captures this feature of the physiological responses. These periodicities are interesting because many midbrain neurons are tuned to fluctuations in this frequency range. Single-formant vowels allowed systematic manipulations of the relationship between formant and harmonic frequencies. Larger envelope fluctuations occur when harmonic and formant frequencies are mismatched than when they are aligned. The auditory models suggest that these differences in fluctuation amplitude are significant for responses of higher–order auditory neurons that are tuned to fluctuation rate. The long-term goal is to understand the interrelationship of vowel space and neural responses. Support: NIH-NIDCD-R01-001641(LHC) & NSF-0853929(JMM)
The influence of amplitude modulation depth on perceived roughness of vowels
Authors: Shrivastav Rahul , Kopf Lisa , Eddins David
Published: April 2012

Previous research has shown that roughness perception for vowels is influenced by the waveform amplitude modulation. It was observed that sinusoidal modulation (constant modulation depth of 100%) between 20 Hz and 70 Hz has the greatest impact on perceived roughness of vowels [Shrivastav & Eddins, 2011; JASA, 129, 2661]. The present experiment examined the effects of modulation depth on the perception of roughness for two of 10 vowels used by Shrivastav & Eddins (2011). Synthetic copies of two vowel stimuli selected from the Sataloff/Heman-Ackah database were generated using a Klatt synthesizer. Sinusoidal amplitude modulation was superimposed on each vowel using three modulation frequencies (20 Hz, 30 Hz, and 45 Hz) and five modulation depths (0, -5, -10, -15, and -20 dB). Listeners judged the perceived roughness of each of the 30 speech stimuli (2 talkers x 3 modulation frequencies X 5 modulation depths) by matching it to a comparison sound. The comparison sound consisted of a sawtooth wave, mixed with speech-shaped noise, and amplitude modulated with a raised (power of 4) cosine wave. Results will show how depth of amplitude modulation affects perceived roughness and will help to develop predictive models to quantify roughness. Research funded by NIH.
Relative role of pitch vs. phonation cues in White Hmong tone identification
Authors: Garellek Marc , Esposito Christina , Keating Patricia , Kreiman Jody
Published: April 2012

This study investigates the relative importance of phonation and pitch cues in (White) Hmong tone identification. Hmong has seven productive tones, two of which involve non-modal phonation. The breathy tone is usually produced with a mid- or high-falling pitch contour similar to the high-falling modal tone. Similarly, aside from some pitch differences between the low modal tone and the low-falling creaky or checked tone, production studies have shown that the phonation differences between the two tones are large. Fifteen native listeners participated in two perception tasks, in which they were asked to indentify the word they heard. In the first task, participants heard natural stimuli with manipulated F0 and duration (phonation unchanged). Results indicate that the phonation of the stimulus is important in identifying the breathy tone, but not the creaky one. Duration and F0 were more closely tied to creaky tonal identification than phonation. In the second task, source spectrum components were manipulated to create stimuli ranging from modal to breathy sounding, with the F0 held constant. The results of this task indicate that changes in H1-H2 and H2-H4 are independently important for distinguishing breathy from modal phonation when F0 is held constant. [Work supported by NSF and NIH]
Speech intelligibility in military noise for normal-hearing and hearing-impaired listeners using level-dependent tactical hearing protectors
Authors: Giguère Christian , Laroche Chantal , Vaillancourt Véronique
Published: April 2012

The effects of two tactical headsets with level-dependent hearing protection capabilities on face-to-face speech intelligibility in military noise were investigated. Devices were the Nacre QuietPro and the Peltor Powercom Plus. Noises recorded from light-artillery vehicles in the Canadian Forces were reproduced in a simulation room at 80-95 dBA. Over 45 subjects covering a wide range of hearing profiles were tested using sentences from the Hearing-In-Noise Test. When used as passive devices with the electronics powered off, the devices performed as expected from conventional protectors having the same amount of attenuation. In this mode, there were large performance differences among subject groups in terms of the effects of wearing the devices compared to unprotected listening. When used in active talk-through (or surround) mode, both devices showed large intelligibility benefits over the passive mode and demonstrated a level of performance often exceeding that in unprotected listening. The subject group with the most impaired hearing benefitted the most from the active mode. The findings indicate that the current technology of high-end tactical headsets could provide substantial benefits in situational awareness during noisy military operations for a wide range of hearing profiles. [Work based on Defence R&D Canada Contractor Report DRDC Toronto CR-2011-101.]
The usefulness of the modified nonsense syllable test as a measure of speech identification
Authors: Shrivastav Mini , Eddins David
Published: April 2012

The NST is a standardized speech-identification test involving closed-set identification of nonsense syllables. Its organization permits speech-identification testing with a variety of consonants and vowel contexts, but its usefulness is limited by the long time it takes to administer and the limited confusion matrices that can be generated. A modified version of the NST (MNST) was developed by Gelfand et al. (1992). They reported data on young normal-hearing listeners at presentation levels ranging from 20 dB to 52 dB SPL in quiet and in noise. A previous study extended the work of Gelfand et al. (1992) to higher presentation levels more suited for older and/or hearing impaired listeners. This work indicated that the MNST is a potentially useful measure of nonsense syllable identification. A significant advantage of the MNST is that it allows detailed analyses of consonant confusions among all the test consonants while reducing the test time greatly. The present work describes the confusion matrices of the two subsets of the MNST for a group of young normal-hearing listeners. This work further validates the MNST and its usefulness as a tool for measuring speech-identification scores and generating detailed consonant confusion matrices in a relatively short amount of time. The above work was supported in part by NIH NIDCD 5R03DC10266-2 awarded to the first author.
The role of context in the perception of environmental sounds
Authors: Risley Robert , Shafiro Valeriy , Sheft Stanley , Balser Adam , Stiles Derek , Gygi Brian
Published: April 2012

Past work has shown involvement of context in the perception of sequences of meaningful speech sounds. The present study extended investigation to meaningful environmental sounds, evaluating the accuracy in identifying individual sources in sequences of five environmental sounds that were either likely or not to have occurred together in place and time. Rating of sequence coherence confirmed the subjective distinction between sequence types. In the main task, young normal-hearing listeners were instructed to identify and order each sound they heard by selecting from among 20 randomly selected labels. Listeners were significantly more accurate in reporting both the names and order of the sounds of the coherent sequences in which sounds were more likely to have occurred together. If not scored in terms of source order, a smaller but still significant difference was obtained between coherent and incoherent sequences. For both sequence types, there was a trend for best performance for the initial and final sources of the sequences. Overall, results are consistent with speech findings and demonstrate a positive effect of context in the perceptual processing of environmental sounds. [Work supported by NIH/NIDCD.]
A model-based acoustical signal processing method for the passive ranging of sniper gunfire
Authors: Ferguson Brian G. , Lo Kam W.
Published: April 2012

Acoustically, sniper gunfire is characterized by a muzzle blast caused by the discharge of a bullet from a rifle and a ballistic shock wave emitted along the trajectory of a supersonic bullet. The location of the firing point can be estimated by using a small microphone array to measure the differences in the angles- and times-of-arrival of the muzzle blast and shock wave. Traditionally, the bullet is assumed to travel at constant speed along its trajectory which, in practice, can lead to significantly biased range estimates. This problem is solved by invoking a physics-based model to describe the deceleration of the bullet along its trajectory. The ballistic model parameters are the initial (or muzzle) velocity and ballistic constant of the bullet, which are assumed to be known a priori. The performances of the traditional and model-based methods for ranging the point of fire are evaluated using 2,500 rounds of 5.56 and 7.62 mm ammunition fired at ranges of 75, 175, 275, 375 and 475 m under two (low and high) wind speed regimes. It is found that the localization errors of the model-based method are smaller by an order of magnitude when compared with those of the traditional method.
Passive sonar target localization and tracking using sequential bayesian filter in uncertain sea environment
Authors: Zhao Hangfang , Gong Xianyi , Yu Zibin
Published: April 2012

A problem of localizing and tracking an acoustic source is researched when ocean environment including water column sound speed profile, ocean depth and seabed property is uncertain. In a Bayesian framework, the source and environmental parameters are regard as random variables with known prior knowledge, then the prior knowledge of parameters and acoustic model are combined with a likelihood function of data to provide posterior probability density functions (PDF) of both south and environmental parameters, target location parameters are estimated by marginalization integrates over the environmental parameters finally. In other hand, the environmental parameters and target location parameters evolve in time or space, which can be described by state-space model. Information on these parameters evolution and uncertainty at preceding steps can be incorporated to determine future probability of parameters with acoustic data being available at current step. A framework of a sequential Bayesian filter is derived naturally based on the model. A Kalman filter or particle filter could be used to implement the sequential Bayesian filter depend on the linear or nonlinear of the measurement equation or/and the state equation. The sequential Bayesian filter is demonstrated to be able to localize and track a source broadcasting a broadband signal in shallow water using both simulated and real data acquired by a towed array.
Quasi real time monitoring system for the tomographic reconstruction of the vortex wind field
Authors: Li Haiyue , Hirasawa Takuya , Yamada Akira
Published: April 2012

Quasi real time vortex wind field monitoring system for the tomographic reconstruction of the vortex wind velocity field was developed. The system was implemented by installing the multichannel sound transmitter and receiver pairs on both sides of the monitoring area. Sound wave travel time data were measured between the arbitrary combination of the facing transmitters and receivers. To speed up the multichannel data collection time, transmission and reception was made in parallel by sending the coded modulation signals. The demodulation correlation calculation, for the extraction of the desired data from the multiple transmission signals, was made in high speed by using GPU (Graphics Processing Unit). Test examination, using the four channel indoor system, showed the promise to complete the vortex wind velocity image production about every 1 s.
A numerical study of temporal variation of low-frequency sound observed in the obs measurement off the east coast of Taiwan
Authors: Huang Chen-Fen , Lin Shih-Chieh
Published: April 2012

The ambient noise recorded by the OBS system deployed off the east coast of Taiwan in the TAIGER (TAiwan Integrated GEodynamics Research) project was employed to obtain the Noise Cross-correlation Functions (NCF). The data were recorded between the stations located at Yaeyama Ridge (water depth about 4000 m), starting from May of 2008 for a period of more one year. The results of NCF have shown that there exists strong microseism energy in the frequency band between 0.16 Hz and 0.35 Hz all year around, and has also demonstrated a large temporal variations as much as 5 seconds. A series of numerical simulations using OASES was conducted to investigate the effect of various waveguide propagation conditions on the temporal variation of NCF. The analysis may potentially pave the way of applying passive acoustic tomography for the monitoring of ocean climate.
Underwater acoustic measurements and simulations from air-gun array of R/V Marcus G. Langseth in TAIGER experiment in the west coast of Taiwan
Authors: Wu Jeff C. H. , Chiu Linus Y.S. , Chen Chi-Fang , Wei Ruey-Chang
Published: April 2012

The high-level noise produced by air-gun array of R/V Marcus G. Langseth was highly possible to impact on marine mammals. However, the west coast of Taiwan is the habitat of many marine mammals, so the environmental impact of the air-gun array noise is extensively concerned. The source level and beam-pattern of the air-gun array have been estimated by the previous study in the east coast of Taiwan. According to the known source level and beam-pattern, sound pressure level can be calculated and compared with the measured data from the air-gun array in the west coast of Taiwan. This study may be taken as a reference to understand the sound propagation and impacts on marine mammals in the west coast of Taiwan. (Sponsored by National Science Council of Republic of China under project “Noise Monitor of TAiwan Integrated GEodynamics Research (TAIGER) Experiment – Middle Section of Taiwan West Coast” No. NSC98-2119-M-110-002)
Modeling binaural speech intelligibility in spatial listening conditions
Authors: Brand Thomas , Rennies Jan , Beutelmann Rainer , Warzybok Anna , Kollmeier Birger
Published: April 2012

Speech intelligibility is substantially improved when speech and interfering noise are spatially separated. This spatial unmasking is mostly caused by a combination of head shadow and binaural auditory processing. Binaural speech reception thresholds (SRTs) in such spatial conditions can be predicted very accurately using a combination of an Equalization-and-Cancellation (EC) model and the Speech-Intelligibility-Index (SII). This binaural speech intelligibility model predicts effects including levels, frequency spectra, and directions of the speech and noise signals as well as listeners' hearing loss, early reflections and reverberant parts of the noise signals. Earlier versions of the model were only able to predict the intelligibility of near-field speech. Recent extensions can also predict the intelligibility of far-field speech by taking early reflections and reverberant parts of the speech signal into account. However, some interactions between the direction of the noise source and early speech reflections cannot be predicted yet. The overall high prediction accuracy of the model (more than 90% of the data's variance can be explained) indicates that the model is applicable in real rooms and may serve as a tool in room acoustical design. This work was supported by the Deutsche Forschungsgemeinschaft (SFB TRR 31).
Predictions of spatial release from masking from architectural plans
Authors: Jelfs Sam , Culling John
Published: April 2012

Spatial separation of target speech and interfering noise produces spatial release from masking (SRM). A model of SRM for speech in noise gives accurate predictions for multiple noise sources and in reverberation. The model is based on the frequency-weighted combination of better ear listening and binaural unmasking. Here we use this model to explore the effects of room acoustics, seating choice, listener head orientation and table layout in a virtual restaurant simulation. The modeled restaurant contains nine tables for two in three rows, and each diner listens to their partner across the table. Substantial SRM was predicted in all seating locations, but was lowest at the centre table. Orienting the head away from the target voice by 20-30deg improved SRM for most seating positions, but this benefit was small for those seated at the edges of the restaurant and facing in. Reorienting these tables so that they have a wall at one side improved average SRM. Acoustic treatments applied to the walls produced larger benefits in SRM than treatment of the ceiling that achieved equivalent reverberation time. Reverberation reduced both SRM and its variability across seating locations and head orientations.
Sub-cortical envelope and fine structure cues: the interaction of age and individual differences for normal-hearing adults in complex environments
Authors: Ruggles Dorea , Bharadwaj Hari , Shinn-Cunningham Barbara
Published: April 2012

Attending to a stream of speech amid competing speech in the presence of reverberation is an everyday task that many adults with normal hearing thresholds take for granted. Recently, though, we've shown that this ability varies widely for individual young and middle-age listeners and that the variability is not related to listener age. In this follow-up study, we recruited additional middle-aged listeners whose data reveal important differences between young and middle-age normal hearing adults and their use of fine structure and envelope cues in directed spatial attention. Twenty-two listeners ranging in age from 20 to 55 years completed spatial selective attention and frequency modulation (FM) detection tasks and had passive frequency following responses (FFRs) to a monotonized /dah/ syllable recorded with scalp electrodes. Although spatial selective attention ability was unrelated to age, older listeners were more impaired by reverberation than younger listeners. The FFR data was analyzed with a method that separates the contributions of fine structure and envelope phase locking, and results depict an age-related transition in envelope and fine structure relationships with complex listening.
Performance of binaural technology for auditory selective attention
Authors: Fels Janina , Masiero Bruno , Oberem Josefa , Lawo Vera , Koch Iring
Published: April 2012

A room-acoustic situation with many sources is one of the best examples for auditory selective attention – relevant information should be selectively observed and irrelevant information should be ignored. In a joint research project between Acoustics and Psychology at RWTH Aachen University the intentional switching of auditory selective attention is examined using dichotic and binaural presentation of the stimuli. The goal is to provide artificially generated acoustic scenes (e.g. typical classroom situation, open plan offices etc.), as in psychoacoustic experiments on auditory selective attention no differences between a real situation and an artificially generated situation occur. Therefore at first we investigate various binaural reproduction and equalization methods using experiments in auditory selective attention. Headphones must always be adequately equalized if they are to deliver high perceptual plausibility. However, the transfer function between headphones and ear drums varies between different persons. Because of this, individual equalizations with different microphone positions in the ear canal are measured. In listening tests the overall quality of the equalization methods is to be rated regarding localization and realism, envelopment as well as immersion. First results concerning the psychoacoustic experiments, the scene generation as well as headphone equalization will be presented.
Perceptual metrics in elementary classrooms and their correlations to student achievement
Authors: Wang Lily M. , Ronsse Lauren M.
Published: April 2012

Binaural impulse response measurements have been made at multiple locations within 20 unoccupied elementary school classrooms in a public school district in Nebraska, USA. Assorted objective metrics have been calculated from these binaural impulse responses, including speech transmission index, distortion of frequency-smoothed magnitude, interaural cross-correlations, and interaural level differences. This presentation highlights the results of these measurements within each classroom and between classrooms. These metrics have been correlated to student scores on standardized achievement tests, obtained as averages for each classroom. One interesting finding is that the distortion of frequency-smoothed magnitude was found to be significantly related to student achievement scores in the language subject areas, even though classroom reverberation times were not, due to the limited range of reverberation times across this investigation.
Speech intelligibility improves with listening exposure in reverberant rooms
Authors: Zahorik Pavel , Brandewie Eugene , Srinivasan Nirmal Kumar
Published: April 2012

Emerging evidence suggests that speech perception in a reverberant room can be altered by recent listening exposure to the room. This result is interesting and important because it suggests that perceptual aspects related to room acoustics are not constant as a function of listening time, and it may help to better understand why hearing-impaired listeners often report difficulty with speech understanding in reverberation. Virtual auditory space techniques have been a key component of the research on this effect, since they allow both realistic simulation of reverberant room listening environments, and a level of stimulus control that would be impossible for real-room listening. Here, recent work demonstrating objective improvements in speech intelligibility with room exposure is summarized, with particular focus on details of the effect including its time course and its sensitivity to different speech materials. [Work supported by the NIH/NIDCD.]
Effect of the inter-aural sound level differences on the speech intelligibility
Authors: Park Chan Jae , Haan Chan Hoon
Published: April 2012

It was defined from the results of many previous researches that the most effective criterion affecting sound clarity in rooms is the early reflected sound. C80 and D50 were used to evaluate sound clarity in rooms. These parameters are related with the sound energy in function of time and they are monoral indexes which do not count for the spatial information including sound directions. Thus, C80 and D50 do not consider the changes of sound clarity caused by difference of sound energy between left and right ears. The proposed study investigates the effect of the inter-aural sound level difference (ILD) on the speech intelligibility in classrooms which can be occurred by the absorption of interior surfaces. In order to do this, sound levels were measured with inter-aural differences of D50, C80 (ID-D50, ID-C80) using dummy-head binaural recording systems. As a result, it was clearly found that ILD was much increased beyond JND after sound absorptions were implied in room. Also, the correlation coefficient of ILD with the distance from sidewalls has increased from 0.696 to 0.890 after sound absorptions. However, there was not clear difference in other parameters (ID-D50, ID-C80). It is also denoted that the increase of ILD can affect the subjective speech intelligibility as well.
Coping with uncertainties in the design and evaluation of acoustical assemblies
Authors: LoVerde John , Dong Wayland
Published: April 2012

The statistical uncertainty in acoustical testing has been insufficiently studied in the acoustical community, and the effects of the uncertainties have been largely ignored. Most acousticians do not know what the reproducibility limit is for acoustical test results from accredited laboratories, but tacitly assume that the limits are on the order 1 or 2 rating points. In recent years the authors have demonstrated that the uncertainties in acoustical laboratory testing in the United States are much higher than most people have realized [LoVerde and Dong, J. Acoust. Soc. Am. 125, 2629 (2009), J. Acoust. Soc. Am. 126, 2171 (2009) J. Acoust. Soc. Am. 130, 2355 (2011)]. The typical acoustician's reaction is that it should be possible to measure to higher precision with suitable changes to the test methodology, and improving the precision of laboratory testing is an important goal that deserves much more attention than it has received. However, there is no guarantee that it will be practical to substantially decrease the uncertainties in acoustical testing, and regardless, the uncertainties characterizing the existing body of research cannot be changed. Accepting this fact demands some changes to how acoustical consultants design assemblies, evaluate products, and interact with clients and regulatory agencies.
A ten year evaluation of the sound insulation of a volume based lightweight construction system
Authors: Öqvist Rikard
Published: April 2012

Since the middle of the '90s, Lindbäcks Bygg, a company in the North of Sweden has developed a lightweight timber construction system with industrially prefabricated room volumes. During these years, a lot of acoustic measurements have been performed. This information constitutes a valuable body of knowledge for future development of the system. However, the measurements have been performed by many different actors and are thus documented in many different ways, which means that it is difficult to get an overview. The aim of this project is to categorise all measurements of impact and airborne sound insulation that have been made on the volume system during the last ten years and to acoustically evaluate the significant constructional changes that have been implemented. A method to document previous and future measurements and link them to constructional parameters will be presented.
Rating the impact sound insulation of flooring from its airborne sound reduction index
Authors: Dodd George
Published: April 2012

With the increasing adoption of higher density forms of dwellings in urban environments we need reliable but economic means of verifying that they meet specified sound insulation requirements. This is particularly so now that territorial and building code authorities are realising that performance checking is an indispensible part of the quality assurance process. This presentation concerns a simplified way of confirming the impact noise insulation in buildings. This makes impact sound insulation rating possible without the need to make impact sound pressure level measurements. The technique estimates the impact sound level by using an accelerometer attached to a hammer (similar to those used in the standard tapping machine) to measure the reaction force from the floor and combines this with the floor's sound reduction index. The method simplifies the equipment required for impact sound insulation rating and allows measurements to be made in the presence of high background noise.
A study on performance of ventilated soundproof windows with fans
Authors: Huang Shih Pin , Lai Rong Ping
Published: April 2012

The research discusses sound insulation on some designed types of ventilated soundproof windows which combine with fans and the air lead-in boards. Conclusions are as the following, The result shows that the type of left-inlet and right-outlet could reach 30.4 dB(A) of sound insulation and the type of double-sided duct could reach 30.7 dB(A) of sound insulation. Changing glass thickness of window, 5mm and 10mm, the sound insulation of ventilated soundproof windows show that frequency response are almost the same by comparing three different types. It shows that has no improvement of sound insulation by adding the glass thickness. Discussing the influence of indoor environment due to fan noise. For the type of normal ventilation, the noise is 41.2 dB(A) when the fan set at the middle speed with air lead-in boards. For the type of double-sided duct, the noise is 33.7 dB(A) when the fan set at the middle speed with air lead-in boards. For the type of left-inlet and right-outlet, the noise is 36.4 dB(A) when the fan set at the middle speed with air lead-in boards. Acknowledgment of support to National Science Council, NSC 100-2221-E-244 -019
Stud effect of plasterboard partition on sound transmission
Authors: Lee Sungchan , Chung Jinyun , Im Jungbin
Published: April 2012

The plasterboard partition is composed of plasterboard, stud, runner and insulation; each component influences sound insulation performance of partitions. In this study, the sound insulation of plasterboard partitions varied in stud thickness and spacing was investigated. The partition was composed of two layers of fire-proof 12.5 mm plasterboard each side, single frame of 50 mm stud and 24 kg/m3 50 mm glass wool. The stud spacing was varied from 450 to 900 mm and the thickness of stud was 0.5 and 0.8 mm. The results showed that the sound insulation of plasterboard partitions was improved by increasing stud spacing and decreasing stud thickness.