bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of multimodal communication during courtship in Malawi cichlids
Authors: Smith Adam R. , van Staaden Moira J.
Published: October 2013

The cichlids of Lake Malawi are often considered the quintessential example of a species radiation driven primarily by sexual selection and relying on visual cues. However, the description of sound production by courting males in several species raises the possibility that acoustic signaling may play a significant role in the selection process. This study describes the mating calls from multiple species in the genera Melanochromis and Metriaclima in order to discern if there is active selection of call characteristics between closely related species or whether differences are more likely the result of drift. Variation in total call duration and fundamental frequency within genera often exceeded that between genera, particularly between the sister species Melanochromis johanni and Melanochromis cyaneorhabdos. This suggests that mating calls may indeed be subject to divergent sexual selection in closely related species. Moreover, in situ sound recordings from Lake Malawi indicate that this behavior is of ecological relevance and not simply an artifact of laboratory conditions. Together, these results suggest that current models of sexual selection in Malawian cichlids may benefit from consideration of previously ignored sensory modalities. The plasticity inherent in such multimodal processing may prove of particular importance to the species-rich African cichlid radiation.
The effects of encapsulation on growth and dissolution of a contrast microbubble
Authors: Sarkar Kausik , Jain Pankaj
Published: October 2013

Micron-size gas bubbles are intravenously injected into patients body at the time of ultrasound imaging to improve image contrast. The bubbles are encapsulated by a thin layer (4–10 nm) of protein, lipids, and other surface active materials, to prevent their premature dissolution in the blood. We will present a model for the dissolution of the microbubble that accounts for the effects of encapsulation. The encapsulation hinders the permeability of the gas-liquid surface and its elasticity balances the surface tension-induced stress. Both these effects will be explicitly modeled. The model behavior will be discussed for variations of the material parameters and conditions (encapsulation permeability and elasticity, mole fraction of the osmotic agent and liquid saturation). The encapsulation significantly affects the bubble growth and dissolution including their time scales.
High-output microsized earplug driver system for extreme acoustic environments
Authors: Kim Keehoon , Kostrzewski Andrew , Daniels Reginald
Published: October 2013

Hearing protection is critical when aircraft flight operations create a high-noise environment (130–150 dB) for aircrew and service members. Untreated aircraft noise causes noise-induced hearing loss (NIHL) and poses risks of similar hearing damage in the future. The authors have developed a new microsized smart material actuator (MSMA), a high-output earplug driver for active noise reduction (ANR) hearing protection, based on highly efficient microstructured acoustic exciters. The MSMA consists of a microscale earplug (MEP) with a proprietary acoustic structure, a protective MEP package, and a compact actuation amplifier easily connected to an external ANR controller. Performance tests show that the system produces over 130 dB into a 1-cc trapped cylindrical volume, 6 mm in diameter by 7 mm long, without significant phase delay or noticeable discontinuities in frequency response.
The surface and bulk microfabrication of optical seismometers and vibrometers using Sandia National Laboratories’ silicon micromachining technology
Authors: Okandan Murat , Hall Neal A. , Littrell Robert , Bicen Baris , Degertekin F. L.
Published: October 2013

The microfabrication of optical seismometer and vibrometer structures using Sandia’s silicon-based process technology is presented. The structure employs a 1.5-mm-diameter polysilicon diaphragm anchored to a 200- to 400-μm-thick bulk silicon proof mass, and suspended by surface micromachined polysilicon springs. Motion of the diaphragm is detected using an integrated polysilicon surface micromachined grating-based optical interferometer. Initial dynamic characterization of these structures in vacuum shows a fundamental resonant frequency of 250 Hz. Based on the high force sensitivity of these structures combined with interferometric motion detection, 1-μg/√Hz detection resolution in the 1-Hz frequency range is estimated. Microfabricated structures employing electrostatic actuation electrodes for the diaphragm are also presented, which enable force feedback operation for high dynamic range and enhanced dc stability. These characteristics may make these sensors well-suited for seismic and inertial navigation applications.
Methods of fitting a nonaudible murmur microphone for daily use and development of urethane elastmer duplex structure type nonaudible murmur microphone
Authors: Nakajima Yoshitaka , Shikano Kiyohiro
Published: October 2013

Nonaudible murmur (NAM) microphones capturing vibrations directly from the skin without mediation by the air enable the sampling of non-audible murmur with almost the same amplification rate as normal speech. Because they are filtered through the human body, they are robust against air-conducted noises. Soft silicone has been used, which has acoustic impedance close to human flesh, as a sound medium between the electrode of the condenser microphone and the skin by fixing it in a neckband style. We replaced the soft silicone with urethane elastomer, which has self-adhesiveness, to develop a NAM microphone that is easily wearable in everyday life without expendable supplies or supporting devices. It can be fixed to the skin, and it also decreases body movement noises. But miniaturized or sticking-type NAM microphones increased the mixture of air-conducted noises from the back of the microphone and from a gap between the skin and the rim of the microphone. To solve this problem, we created a duplex structure inside the urethane elastomer wrapping condenser microphone and outside the urethane elastomer for fixation and noise proofing to develop a miniaturized sticking-type NAM microphone that was again robust against air-conducted noise.
A study of bone conduction and its applications for audio signal transmission
Authors: Watabe Yusuke , Yui Kochi , Watanabe Yuko , Hamada Hareo
Published: October 2013

Human can perceive a sound in two different ways: one is sound transmission through the ear canal, another is that through the skull. The bone conduction technology has been used mainly for hearing impaired listeners and as communication tools in the military organization. Recently, because of a rapid improvement of the bone conduction device, its technology has spread in the field of audio. However, the relationship between the physical characteristic and the subjective responses of bone conduction are not clearly understood. For example, the effect of attachment position and excitation force of bone conduction loudspeakers has been still under discussion. In addition, since the bone conduction units also generate the airborne sound, listeners can hear the sound composed of both the bone conduction sound and the airborne sound. In our previous work, by using of a loudness curve and a threshold of hearing, a fundamental performance of the bone conduction was discussed. In this paper, further investigation will be carried out in order to establish a transmission system of the bone conduction, and the airborne sound on the eardrum that is caused by the vibration of the bone conduction loudspeaker will be measured.
Differences between cylindrical and conical brass instruments; the nonlinear propagation point of view from experiments and simulations
Authors: Gilbert Joel
Published: October 2013

The brightness of the sound generated by brass instruments is due to the essential nonlinearity of the wave propagation in the pipe. The bright instruments such as the trumpet and the trombone are different from brass instruments such as saxhorns or flugelhorns. The bright instruments have a cylindrical pipe segment just downstream of the mouthpiece. The conical bore of the saxhorns implies a faster decay of the wave, which reduces the nonlinear wave steepening. In this talk, theoretical and experimental results of brassiness associated with brass instruments having different bores, from mainly cylindrical ones to mainly conical ones, will be shown. The theoretical results come from simulations of periodic regimes using a theoretical background based on generalized Burger’s equations.
Effect of atmospheric absorption on aircraft noise propagation in various world regions during the year
Authors: Okada Yasuaki , Yoshihisa Koichi , Iwase Teruo
Published: October 2013

The attenuation of sound due to atmospheric absorption depends strongly on environmental temperature and humidity. For that reason, it varies in response to changing meteorological conditions on a variety of time scales. To perform long-term prediction of outdoor sound propagation more accurately, it is necessary to examine the fluctuation of the attenuation coefficients for atmospheric absorption during the year. Large variations occur according to the time and place in actual meteorological conditions, on which the attenuation coefficients depend strongly. The attenuation coefficients for atmospheric absorption were calculated from hourly meteorological data obtained at ten international airports throughout the world during a year using the calculation method described in ISO 9613-1. Calculated results show that the variability characteristics of the attenuation coefficients during the year depend strongly upon both the sonic frequency and the place. The effects of atmospheric absorption on aircraft noise propagation were examined using the calculated attenuation coefficients. Results showed that the A-weighted sound pressure levels and sound spectra of aircraft noise vary strongly because of the changes in atmospheric absorption, which depend on actual meteorological conditions of various world regions.
A comprehensive noise study for the city of Lincoln, Nebraska
Authors: Cheenne Dominique , Lee Connie , Cappiello Michael , Lalk Sam , Martin Coleman , Muzzy Philip
Published: October 2013

A comprehensive noise study to define the soundscape of the city of Lincoln, NE, has been undertaken by the students enrolled in the Acoustics Program at Columbia College, Chicago. The study includes (1) a global review of best practices in the field of environmental noise control using a perspective emphasizing close attention to effective and proven solutions that can be implemented via policies and effective legislation, (2) the creation of a large-scale outdoor noise propagation computer model that incorporates all primary traffic arterial and readily identifiable noise sources, (3) a comprehensive large-scale testing of noise levels using specially modified noise dosimeters allowing for determination of Leq, and Ldn over 24-h intervals, and (4) a large scale attitudinal survey of the population using a web-based survey engine that allows for the geographical location of the respondents. The results of the survey are used to refine the density of the test locations and the scale resolution of the software model, as well as to provide city and county officials with a targeted course of action pertaining to regulations and noise abatement policies. The project is expected to last 3 years with up to 1200 test locations being analyzed.
Bauxite refinery community noise control and prediction
Authors: Nepomuceno Jose Augusto , Machado Aljan
Published: October 2013

Alumar in the city of Sao Luis in Brazil is one of the largest bauxite processing plants in the world including refinery and reduction plants. The Alumar refinery will expand from approximately 1.4 million mtpy to approximately 3.5 million mtpy and the expansion is expected to be completed in the first half of 2008. Since the year 2000 the authors worked in collaborative way with the in-plant and community noise control and prediction program for the expansion project. The program included noise measurement in the existing plant, development of the Bauxite Refinery Noise Control Manual, several noise control guidelines, and noise modeling to predict community noise impact. The plant is surrounded by different land uses as residential, industrial, rural, and natural permanent protection. Using computer modeling it was studied how the refinery expansion could impact the community areas and what will be the critical equipment requiring special noise limits. The validation process predicted measured results in the range of +2.2 dB(A). The paper presents the noise program results obtained by the year 2006.
Statistical models for fading and coherence of sound in urban environments
Authors: Wilson D. Keith , Bey-Hernandez Rafael , Ostashev Vladimir E.
Published: October 2013

Urban environments typically produce strong, multipath scattering. It is often desirable to characterize the effects of the scattering with statistical models for signal fading and coherence. This paper discusses initial efforts to develop such models. Random configurations of buildings, with varying sizes and number densities, are synthesized. Sound waves are then propagated through the random configurations. The first and second moments of the sound field are calculated by averaging results from the random realizations. Most of the propagation calculations are done by a ray-tracing technique, which is very fast but does not include diffraction. Due to multiple scattering, cases where a receiver is in a full acoustic shadow are infrequent. We also compare the ray tracing to finite-difference, time-domain calculations, which provide a full-wave solution that includes diffraction as well as multiple scattering. Initial results show that the wave extinction and coherence diminish exponentially with distance, as is the case for turbulent scattering. The extinction and coherence decay rate increases with the number of buildings and size, but appears to be independent of frequency. We compare the signal probability density functions to statistical fading models developed for radio-wave scattering in urban environments.
An acoustic technique for monitoring off-highway vehicle (OHV) use with sound level meter data: Camparison with Trailmaster records
Authors: Yack Tina , Bowles Ann , Slauson Keith , Zielinski William , Plotkin Kenneth
Published: October 2013

Off-highway vehicle (OHV) use is of growing interest to land managers. Trail counters are typically used to monitor OHV activity, but accuracy of this technique remains relatively untested. As part of an ongoing study comparing the distribution of American martens (Martes americana) with OHV use in the Lake Tahoe Basin, verifiable OHV detections were collected using two techniques, (1) photographs from Trailmaster 1500 camera systems (TMs) placed across roads/trails and (2) continuous 2-s, A-weighted equivalent-continuous sound levels (LAeq2s) collected using Larson-Davis 720 Sound Level Meters (SLMs) placed either near roads/trails or paired with TM animal detection stations. Events were identified in the SLM data by comparing time-history profiles collected in the field with profiles of known snowmobile passes. Errors in SLM event counts were assessed using independent observer logs and compared with the TM records. SLMs were consistently more reliable detectors of snowmobile use. During the Winter 2004 season, TM records were reliably matched to SLM logs only 48% of the time. TMs consistently missed passes and overestimated events compared to SLMs. In conclusion, SLMs proved to be more sensitive and reliable detectors of OHV activity. These results have implications in both wildlife research and land management applications.
A study for applying lower temperature heat source to loop-tube thermoacoustic cooling system
Authors: Imamura Yousuke , Sakamoto Shin-ichi , Watanabe Yoshiaki
Published: October 2013

To realize the generation of self-sustained sound in lower temperature heat source, a 5-μm in thickness rubber membrane was applied in the loop-tube thermoacoustic cooling system. It is known that the existence of dc flow acts as the negative effect for the loop-tube. The membrane reduces a loss of thermal energy supplied to the prime mover by suppressing the dc flow. So it is considered that lower temperature difference between both the edges of the stack can be realized by using presented system. The locating position of the membrane was moved, and then the temperature differences of the stack were observed. The experiments were carried out on the condition that the thermal energy supplied to the prime mover was constant. It was found that the temperature difference is affected by the position of the membrane. When the membrane was set at the approximate antinode of pressure, the lowest temperature difference was realized. In this condition, the temperature difference with the membrane was 430 K, which was 160 K lower than without the membrane. These results suggest that a lower temperature heat source can be available by setting the membrane on the loop-tube thermoacoustic cooling system.
Determination of complex propagation constant, acoustic intensity, and acoustic power in an arbitrarily terminated pipe using laser Doppler anemometry
Authors: Jung Ki Won , Atchley Anthony A.
Published: October 2013

Microphones are widely used to determine acoustical parameters, such as the complex propagation constant and acoustic intensity and power, of sound fields. It is less common to use measurements of acoustic particle velocity for the same purpose. Precise measurement of acoustic particle velocity can be achieved using laser Doppler anemometry (LDA). Although this measurement technique requires optical access to the region of interest and the use of seeding particles, in some circumstances it can be less invasive and offer greater flexibility than measuring pressure fields with microphones. The focus of this research is to use LDA to determine the complex propagation constant, acoustic intensity, and power inside a constant cross-section circular pipe. The measured particle velocities are fit to a counterpropagating plane-wave model to determine the complex amplitudes and propagation constant. Other acoustic quantities, such as the radial-dependent acoustic intensity and the cross-sectional-averaged acoustic power, can then be calculated. The complex propagation constant is compared with the theoretical value based on thermoviscous boundary layer theory. The acoustic intensity and power are compared with numerical solutions to Rott’s wave equation. [Work supported by the Penn State Graduate Program in Acoustics.]
Proper orthogonal decomposition for sensitivity analysis and classification of outdoor sound propagation
Authors: Pettit Chris , Wilson D. Keith
Published: October 2013

Simulations of outdoor sound propagation are compromised by many sources of uncertainty and error. A key step in validating computational acoustics models, which may be interpreted as the act of assessing predictive skill, is estimating ensemble sound pressure variability due to uncertainties in the parameters that define the propagation conditions. This paper describes elementary steps toward achieving this goal. The atmospheric surface layer is represented through Monin-Obukhov similarity theory and the acoustic ground properties with a relaxation model. Randomness is assumed across appropriate ranges of the governing parameters. The parameters are modeled herein as independent random variables, but future efforts will extend this formulation to include random field models of the parameters with varying levels of correlation. Sound propagation is predicted with the parabolic equation method. Latin hypercube sampling (LHS) and proper orthogonal decomposition (POD) are employed to develop low-dimension representations, i.e., reduced order models, of the sound pressure random field. Sensitivity of the sound pressure field is studied via the model-induced sensitivity of the POD mode coefficients to the system parameters as well as statistical dependence on the number of LH samples. Attention is also given to connecting the POD coefficients to documented indicators of refraction conditions.
Auditory priming releases Chinese speech from informational masking
Authors: Yang Zhigang , Chen Jing , Wu Xihong , Wu Yanhong , Schneider Bruce , Li Liang
Published: October 2013

Before an English speech sentence is presented, hearing or reading the sentence without the last key word improves recognition of the last key word if the full-length speech sentence is presented under speech masking but not under noise masking. This phenomenon suggests a content priming effect on releasing speech from informational masking. To determine whether the priming effect extends to tonal Chinese speech, and, in particular, whether it can be induced by the target talkers voice, in the present study, listeners were presented with either same-voice/different-sentence primes or same-voice/same-sentence primes before hearing the target sentence in either two-talker-speech masking or noise masking. Under speech masking, each of the two prime types significantly improved recognition of the last key word in the full-length target sentence, but the content priming is stronger than the voice priming. Under noise masking, same-voice/same-sentence primes had a weak but significant priming effect, but same-voice/different-sentence primes had only a negligible priming effect. These results suggest that both content and voice cues can be used by listeners to release Chinese speech from informational masking, but only content cues are useful for releasing Chinese speech from energetic masking. [Work supported by China NSF and Canadian IHR.]
Auditory memory for frequency in sequential interference
Authors: DiGiovanni Jeffrey J. , Ries Dennis T.
Published: October 2013

Percepts within working memory are weakened by the presence of intervening stimuli that lie along the same perceptual dimension. To this end, the effect of sequential interference on the storage of frequency information within auditory working memory was measured. The difference limen for frequency was measured by the method of constant stimuli for two diotic and two dichotic conditions. The first diotic condition served as a control and consisted of two 300-ms stimuli separated by 5 s. The frequency of the referent (first tone) was roved over a 100-Hz range centered at 435 Hz. Listeners indicated whether the target (second tone) was higher or lower in frequency than the referent. The second diotic condition added four interfering tones between the referent and the target. In the third condition, the interferers and referent/target pair were lateralized to opposite ears via the Stenger effect. In condition four, the phase of the interferers differed between ears by 180 deg. Results indicate (1) the addition of interferers increased the difference limen for frequency, and (2) when the interferer and target/referent pair differed along a single localization dimension, the effect of the interferers was reduced.
Speech recognition in coherently-amplitude modulated noise
Authors: Dhamani Imran , Naveen K. , Rajashekhar B.
Published: October 2013

Comodulation masking release is a phenomenon that improves the detectability of a masked pure tone or speech signal by addition of a coherently amplitude-modulated energy above and/or the signal frequency. The majority of the studies done on comodulation masking release have studied threshold detection for a pure tone, or speech identification at or near threshold levels with a favorable signal-to-noise ratio. Moreover, various studies examining comodulation masking release under conditions of reduced frequency selectivity in listeners with cochlear hearing impairment indicate absence or reduced comodulation of masking release effect (Hall et al., 1984; Hall and Grose, 1985; Moore et al., 1993). In the current study, the speech recognition task was studied for the CMR effect at supra-threshold level and unfavorable signal-to-noise ratio of −10 dB. Results indicated absent CMR effect at supra-threshold level for the word recognition task for normal-hearing individuals.
Lateralization of sine tones—Interaural time versus interaural phase
Authors: Zhang Peter X. , Hartmann William M.
Published: October 2013

Five listeners estimated the lateral positions of 50 sine tones in a headphone experiment designed to determine whether the human sense of sound location correlates better with the interaural phase difference (IPD) or the interaural time difference (ITD). In any experimental block the IPD values ranged from −150 to +150 degrees, and the frequencies were chosen such that the ITDs ranged from −1000 to +1000 microseconds. The frequencies were all in the range where human listeners are known to be able to lateralize tones based on the ITD in the waveform fine structure. It was found that the lateralization responses correlated with the ITD much better than with the IPD. The average variance was five times smaller for the ITD hypothesis compared to the IPD hypothesis, and only the ITD hypothesis led to a well-fitting (compressive) function. For the ITD function, individual compressive exponents varied considerably and averaged 0.75. For the IPD function the exponents were too small to be meaningful. Comparison with previous lateralization studies indicates the importance of presenting the entire range of stimulus parameters in all experimental blocks because it appears that listeners tend to use the entire range of allowable responses in any block. [Work supported by the NIDCD.]
Head-related transfer functions via the fast multipole accelerated boundary element method
Authors: Gumerov Nail A. , Duraiswami Ramani , Zotkin Dmitry N.
Published: October 2013

Computation of head-related transfer functions (HRTF) via geometrical meshes and numerical methods has been suggested by a number of authors. An issue facing this approach is the large computational time needed for high frequencies, where the discretization must include hundreds of thousands of elements. Conventional computational methods are unable to achieve such computations without excessive time or memory. We use a newly developed fast multipole accelerated boundary element method (FMM/BEM) that scales linearly both in time and memory. The method is applied to the mesh of the widely used KEMAR manikin and its HRTF computed up to 20 kHz. The results are compared with available experimental measurements.
Vibro-acoustic analysis using hybrid finite element, boundary element, and statistical energy analysis models
Authors: Shorter Phil , Cotoni Vincent
Published: October 2013

This paper presents an overview of the theory and application of the hybrid FE-SEA method. The method provides a rigorous way to model the fully coupled response of a vibro-acoustic system across a broad frequency range using a combination of FE, BEM, and SEA. The theory of the method will be discussed and results from the following applications will be presented: (i) modeling the transmission loss and radiation efficiency of trimmed automotive subassemblies; (ii) creating efficient models of structure-borne noise in an automotive body-in-white; (iii) modeling structure-borne noise transmission in a commercial aircraft fuselage; and (iv) modeling the response of a satellite antenna to broadband acoustic loading.
Reconstruction of vibro-acoustic response of a plate using Helmholtz equation least-squares method
Authors: Lu Huancai , Wu Sean F.
Published: October 2013

A numerical investigation of reconstructing the vibro-acoustic responses of an arbitrary structure subject to vibration excitations based on the Helmholtz equation least-squares (HELS) method is presented. It is emphasized that in many engineering applications, the exact solution to a general vibrating structure does not exist, and the HELS method is one way of getting approximate solutions in a cost-effective manner. In this study, the test object is a simply supported, unbaffled thin plate. The reason for selecting this simply supported plate is that the analytic solutions to the plate vibrations are readily available. The field acoustic pressures generated by the Rayleigh integral are taken as input to HELS algorithms to reconstruct the normal velocity and normal acoustic intensity on the plate surface using Tikhonov regularization associated with generalized cross-validation methods. The reconstructed normal surface velocities are compared with the benchmark values, and the out-of-plane vibration patterns at the first five natural frequencies are compared with natural modes of the simply supported plate. The effects of measurement aperture, stand-off distance, and location of the origin of the coordinate system on the resultant accuracy of reconstruction are examined. [Work supported by NSF.]
Application of the short-time Fourier transform and the two-dimensional Fourier transforms to detect damage in plates
Authors: Assaad Jamal , El Youbi Faysal , Grondel Sebastien , Moulin Emmanuel
Published: October 2013

Lamb waves are widely used in the fields of characterization and nondestructive testing of structures. Usually, the full characterization of the structures requires two kinds of information: the first one is related to the material quality, the other one aims at the evaluation of the structure health, i.e., the detection of localized damage or defects. Time-frequency analyses or two-dimensional Fourier transforms (2DFT) have been used separately to solve such a problem. The purpose in this work is therefore to present a dual signal processing approach based on the relationship between the STFT (short-time Fourier transform) and the 2DFT amplitudes that allows a better interpretation and identification of Lamb modes. This relationship will be numerically verified by a two-dimensional finite-element method. Experimentally, a 3-mm-thick aluminum plate with an emitter and a receiver are considered. The emitter consists of two piezoelectric transducers while the receiver consists of a 32 multi-electrode piezoelectric transducer. This receiver has been developed especially to increase signal-to-noise ratio at the reception. In order to simulate damages a hole with different diameter was introduced in the plate center. The application of this dual signal processing has located conversion modes phenomenon.
Making young ears old and old ears even older: Simulating a loss of synchrony
Authors: MacDonald Ewen , Pichora-Fuller Kathy , Schneider Bruce , Wong Willy
Published: October 2013

Age-related changes in the auditory system have been attributed to three independent factors: OHC damage, changes in endocochlear potentials, and loss of neural synchrony. In previous studies, a jitter algorithm has been used to simulate the loss of synchrony in young adults (MacDonald et al., 2005). In this study, the effect of jitter on old adults with good audiograms in the speech range is explored. SPIN-R sentences were presented in two SNR and three processing conditions: intact, jitter, and smear. The parameters of the jittering algorithm were the same as those used with young adults. The parameters of smearing algorithm were chosen to match the spectral distortion produced by jitter algorithm. While both the jitter and smear conditions resulted in a significant decline in word identification, the decline was largest in the jitter condition. Psychometric functions were fitted to the data and compared to previous work with young adults. The comparison supports the hypothesis that loss of synchrony can adversely affect speech intelligibility in noise, and is consistent with the hypothesis that loss of synchrony occurs with age. As well, the comparison suggests that the effect of jitter may be linear.
Audiovisual perception of voicing with age in quiet and cafe noise
Authors: Behne Dawn , Wang Yue , Alm Magnus , Arntsen Ingrid , Eg Ragnhild , Valso/ Ane
Published: October 2013

Research has shown that voicing is difficult to discern in noisy environments. While voicing may be difficult to resolve from visual cues, acoustic cues for voicing are relatively robust. This study addresses these factors with normally aging audiovisual perception. Identification responses were gathered with 19–30-year-old and 49–60-year-old adults for audiovisual (AV) CVs differing in voicing and consonant place of articulation. Materials were presented in quiet and in cafe noise (SNR=0 dB) as audio-only (A), visual-only (V), congruent AV, and incongruent AV. Results show a tendency toward use of visual information with age and noise for consonant place of articulation. Notably for voicing, incongruent AV materials that had one voiced component, regardless if it was A or V that was voiced, were consistently perceived as voiced in both age groups and regardless of noise. Only if the A and V components were both voiceless was the syllable perceived as voiceless. These findings indicate the influence of age and noise in the use of perceptual information to identify place of articulation. That voicing is robustly salient from either audio or visual information, despite the unlikely presence of strong visual cues for voicing, indicates a possible bias toward the perception of voicing.
Older adult’s identification and memory of synthetic and natural speech in noise
Authors: McCarty Candice Q. , Surprenant Aimee
Published: October 2013

This research tested older adult’s performance on identification and recall when presented sentences taken from the Speech Perception in Noise Test [Bilger et al., J. Speech Hear. Res. 27, 32–48 (1984)] synthesized using AT&T Natural Voices speech synthesizer. Performance on synthesized speech was compared to identification and recall of natural speech in noise. In experiment 1, participants were instructed to identify the final word of high- and low- predictability natural and synthesized sentences presented at three signal-to-noise ratios. The results showed that natural speech was easier to identify than synthesized speech at every speech-to-noise ratio for high and low predictability sentences. In addition, replicating Pichora-Fuller et al. [J. Acoust. Soc. Am. 97, 593–608 (1995)], pure tone thresholds were significantly correlated with identification performance for both natural and synthetic speech. In experiment 2, participants were given a sentence span task in which they were presented two to five natural and synthesized sentences and asked to recall the final words. These experiments show that, even with high context, synthetic speech is more difficult to understand and remember than natural speech. These results highlight concerns about the use of synthesized speech in assistive devices, particularly for elderly listeners. [Work supported by NIH.]
Spectral shape discrimination and speech identification in noise in elderly hearing-impaired listeners
Authors: Shrivastav Mini
Published: October 2013

Elderly hearing-impaired listeners have difficulties in the recognition and discrimination of consonants, particularly those that share the same manner of articulation. An important cue that distinguishes the manner of articulation of these consonants is spectral shape. A previous study (Shrivastav et al., 2006) found a moderate predictive relation between spectral-shape discrimination thresholds and syllable identification scores of elderly hearing-impaired listeners, when all stimuli were presented in quiet. The present study examined the contribution of spectral-shape discrimination abilities to speech-identification performance of elderly hearing-impaired listeners in the presence of background noise. The study included a group of elderly hearing-impaired listeners, with a group of young normal-hearing adults included for comparison purposes. Listeners were tested on a series of speech-identification and spectral-shape discrimination tasks, while ensuring that all stimuli were at least minimally audible to all the hearing-impaired listeners. The contribution of spectral-shape discrimination abilities to speech-identification performance in background noise was examined and compared to the results in quiet for young normal-hearing and older hearing-impaired listeners.
Audiovisual speech integration in children with autism spectrum disorders
Authors: Irwin Julia R.
Published: October 2013

Children with autism spectrum disorder (ASD) appear to be less influenced by visual speech information than typically developing children, as measured by their responses to mismatching auditory and visual (McGurk) stimuli. This study examined whether this reduction in sensitivity to the McGurk effect is due to eye gaze aversion, a hallmark of ASD. Children with ASD and typically developing controls (TD) were presented with videotaped consonant-vowel (CV) stimuli. Stimuli were digitally edited to create either an audiovisual (AV) match (AV /ma/ or /na/) or mismatch (audio /ma/ and visual /ga/). Responses were considered visually influenced if participants reported hearing /na/ for the mismatched stimuli. Using eye-tracking methodology, only trials where participant’s gaze was fixated on the speaker’s face during consonantal closure were included in analyses. Initial analyses reveal, when fixated on the speaker’s face, children with ASD show significantly less visual influence relative to typically developing controls. It is proposed that the reduced influence of visual speech information in ASD is best understood at the level of visual speech processing, perhaps arising from a lack of experience with speaking faces. Implications for understanding visual speech processing in typical development and developmental disability are discussed. [Work supported by NIH grant DC-00403 (Cathi Best, PI.]
Auditory temporal order judgments in children with specific language impairment and autism spectrum disorder
Authors: Rosen Sheryl , De Ruiter Mark , Hsieh Li
Published: October 2013

The Tallal repetition test (TRT) measures the ability of listeners to detect, associate, sequence, and remember complex patterns of stimuli (serial memory) The TRT contains sequencing and serial memory subtests with varying short and long interstimulus intervals (ISIs) Three groups of 12 children were tested using a modified version of the TRT. Subject groups consisted of 7- to 10-year old children with typical development (TD), autism spectrum disorder (ASD), and specific language impairment (SLI). The TRT contained both tone and CV syllable stimuli to assess temporal processing. As ISI increased, performance improved for both children with TD and SLI in both tone and syllable sequencing tasks, but not for children with ASD, especially in the tone task. Children with TD and those with ASD performed better than those with SLI across most subtests, especially in tasks with short ISIs. Analysis of performance in the serial memory portion of the TRT revealed a predicted pattern of decreased performance as stimuli elements increased. Overall, children with TD and those with ASD appear to have superior auditory temporal order judgment abilities when compared to children with SLI. The linguistic relevance factor shall be considered in assessment and training of various disordered populations.
Perception of synthesized syllables and sentences by listeners with hearing loss
Authors: Bickley Corine , Dove Amanda , Liacouras Andrea , Mancini Jolene
Published: October 2013

The goal of this project is to create a set of synthesized speech materials that yields listening results equivalent to those that would be obtained using recorded naturally spoken materials, such as the CUNY Nonsense Syllable Test and the CASPERsent set of topic-specific sentences. One research interest of the RERC-HE is the following: Can synthesized speech be used as a substitute for recorded human speech in aural rehabilitation and in hearing aid research? The listeners in this study are both adults with normal hearing and with hearing loss. We have tested two listeners with normal hearing and four with hearing loss using nonsense syllables synthesized with DECtalk. The patterns of errors in their identification of phonemes follow expected patterns when subjects’ responses were analyzed with respect to their audiometric profiles and the acoustic characteristics of the synthesized phonemes. The same group of listeners is now being tested using sentences from the CASPERsent lists synthesized with two commercially available text-to-speech systems: DECtalk, which uses a formant-type synthesizer, and ATT Natural Voices, which uses a concatenative synthesizer. Results of these listening tests will be presented. [This project is funded through the Rehab Engineering Research Center—Hearing Enhancement through the NIDRD.]
Effects of dichotic listening for hearing impaired people
Authors: Sasaki Ai , Murase Atsunobu , Sakamoto Shuichi , Suzuki Yôiti , Kawase Tetsuaki , Kobayashi Toshimitsu
Published: October 2013

Methods applying the dichotic listening algorithm have been proposed and examined for application in hearing aids. Murase et al. (2005) proposed an algorithm in which dichotic listening was simply implemented by a set of complementary high-pass and low-pass filters. One filter is for either the right or left channel; the other filter is used for the other channel. This study examined two unsolved problems with this algorithm. One is the reason why this algorithm is effective. The other is probable degradation of sound localization that occurs because interaural level differences and interaural time differences is only slightly available with this signal processing. This problem is considerable when the sounds come from frontal incidence. Regarding the first problem, intelligibility tests were performed using the low-frequency-boosted sounds. The intelligibility scores under the dichotic listening conditions should be higher than those under the diotic listening conditions if the effectiveness of this algorithm is attributable to the reduction of upward spread of masking. Results suggest that this dichotic listening reduced the upward spread of masking. Regarding degradation of performance of sound localization, sound localization test results suggest that time-intensity trading might recover degradation with dichotic listening algorithm.
Effects of auditory training on hearing aid acclimatization
Authors: Scott Jack M.
Published: October 2013

New hearing-aid users may experience a gradual improvement in speech performance over time that typically plateaus 6–12 weeks following hearing aid fitting. The delayed improvement may be due to neural reorganization of the auditory system following the introduction of amplified auditory input. Unfortunately, 30 days is the typical duration for most hearing aid trial periods; therefore, many individuals may be returning their hearing aids before being able to evaluate the full benefit of amplification. Prior to amplification, listeners with hearing impairment may experience difficulty perceiving subtle high-frequency changes in speech known as second-formant transitions. Second-formant transitions provide cues in discriminating consonant sounds. The purpose of this study was to determine if intensive high-frequency discrimination training for new hearing-aid users could facilitate improvements in speech perception. Speech recognition was evaluated for consonant identification, speech feature perception, and sentence identification in quiet and in noise before and after 10 days of training discrimination of frequency sweeps at 2 kHz. Improvements were found in sentence identification. These results have implications for the use of auditory training to improve speech recognition for newly amplified listeners with hearing impairment.
Vowel production in Swedish children with cochlear implants
Authors: Ibertsson Tina , Sahlen Birgitta , Lofqvist Anders
Published: October 2013

This study analyzed vowel production of Swedish children with cochlear implants. Swedish has a rich vowel system with nine vowels. Minimal word pairs were used as linguistic material. The age of the children varied between 6 and 13 years. The age at implantation was 1.2–10 years. The first two formants were measured for each vowel. To estimate the vowel space, the average Euclidean distance in the F1–F2 plane between each vowel and the mean first and second formant frequencies of all the vowels was calculated for each child. Preliminary results from 15 children with cochlear implants and 11 control subjects with normal hearing show no difference between the two groups, due to a large amount of variability in the group with cochlear implants. The relationship between the vowel space and the speech perception of each child with a cochlear implant was analyzed using correlations. Results show no strong correlation between the two measures, again due to the variability within the group. [Work supported by the Sunnderdahl Foundation.]
Sentence duration and mode of communication in cochlear implanted children
Authors: Wiessner Nicole L. , Tobey Emily A. , Geers Ann E.
Published: October 2013

This study investigates the relationships between mode of communication and speech duration in cochlear implanted (CI) children with 4–6 years experience with their device. One hundred thirty-six CI children between the ages of 8 and 9 years old repeated sentences of three, five, and seven syllables (McGarr, 1983). Durations were examined according to syllable length, low versus high context sentences, and the communication modality of the child’s classroom. Findings suggest that communication modality is more strongly associated with duration than sentence context or length. Significantly shorter sentence durations were found for CI children taught with an auditory-oral emphasis than CI children taught using an emphasis of speech and some form of manual sign system. [Work supported by the NIH.]
Interpolation of vocal-tract shape during stop closures from transition segments in vowel-consonant-vowel syllables
Authors: Shah Milind S. , Pandey Prem C.
Published: October 2013

Children with prelingual profound hearing impairment have great difficulty in acquiring speech. Speech-training systems providing visual feedback of vocal-tract shape are found to be useful for improving vowel articulation. Vocal-tract shape estimation, based on LPC and other analysis techniques, generally fails during stop closures, and this restricts its effectiveness in speech training for production of consonants not having visible articulatory efforts. A technique based on two-dimensional surface modeling of the area values, estimated by LPC analysis, during the vowel-consonant and consonant-vowel transitions preceding and following the stop closure, has been investigated for interpolating the area values during the stop closures. Surface modeling was based on least-squares bivariate polynomials and Delaunay triangulation methods. Syllables of the type /aCa/, /aCi/, /iCa/, /iCi/, and /uCu/ with stop consonants /p/, /b/, /t/, /d/, /k/, and /g/ were analyzed for the estimation of place of stop closure. For bilabial, alveolar, and velar stops, the place could be estimated consistently with conic polynomial surface interpolation. Estimation of place, based on Delaunay surfaces, was consistent for bilabial and velar stops. However, cubic polynomial surface interpolation results were less consistent in estimating the place of constriction.