bluuebunny/crossref_metadata_2025 huggingface dataset:
Relevant psychoacoustic parameters in assessments on wind turbine noise
Authors: Eichenlaub Christoph , Weber Reinhard
Published: July 2002

Subjective judgments on wind turbine noise were to determine noise quality parameters which are related to the unpleasantness of noise immissions. In a pre-test paired comparisons of wind turbine noises using headphone presentations showed the superiority of head related recordings compared to single microphone recordings. Loudness contributed mostly to the unpleasantness and masked the contribution of other noise quality parameters. Hence in the main experiment artificial head recordings from a representative set of ten wind turbines were equalized in loudness and judged after their unpleasantness in a complete paired comparison trial by 22 subjects. Insufficient reliability and consistency led to an exclusion of 9 subjects. From the BTL-scaled answers of 13 subjects a factor analysis provided two factors (F1: 71%/F2: 12% of total variance). Means and percentiles of the unweighted, A-, B-, and C-weighted SPL, loudness, roughness, sharpness, fluctuation strength, tonality and impulsiveness were calculated and answers of 11 subjects with high and moderate loads on factor 1 showed significant correlation coefficients with tonality measures (r=0.8 to 0.83). The answers of subjects with high loads on factor 2 significantly correlated with fluctuation strength. No further noise quality parameters turned out to be relevant.
Response to low-frequency HVAC noise
Authors: Norm Broner , Davies Patricia
Published: July 2002

With the increasing use of variable air volume systems in building air-conditioning, there has been an increased occurrence of low-frequency and rumble noise problems. ASHRAE is currently funding a research program to determine the relationship between low-frequency HVAC noise and comfort in occupied spaces. A pilot psycho-acoustic study was conducted using up to nine subjects. Twelve noise stimuli representing various HVAC sounds were utilised and subjects assigned an annoyance and loudness rating using the absolute magnitude estimation technique. The results showed that for noise stimuli dominated by low-frequency energy, the annoyance was more severe than the loudness, rather than equal as has been generally assumed. The main study is currently underway and some of the results will be discussed. The subjective rating responses were correlated with the dB SPL and other noise metrics and Sound Quality metrics. The results have implications with respect to assessment of low-frequency noise in buildings and possibly to the external environment.
The Indiana Test of Auditory Memory and Processing Rate (ITAMPR)
Authors: Watson Charles S. , Eddins David A. , Kidd Gary R.
Published: July 2002

The Indiana Test of Auditory Memory and Processing Rate (ITAMPR) is designed to measure children’s abilities to identify sequences of speech elements. Subtests determine whether identification performance is primarily limited by the rate at which the stimuli are presented or by the number of stimuli in a sequence. Stimuli consist of 80-ms syllables, /ba/ and /da/, produced using a Klatt synthesizer. Listeners respond by repeating the sequence that they heard. The first subtest determines the fastest rate at which three-syllable sequences can be correctly identified, with rate manipulated by reducing the inter-syllable intervals. The second subtest determines the largest number of syllables that can be correctly repeated, using an intersyllable interval of 400 ms. A third subtest intentionally covaries number of syllables and rate of presentation, to determine the combined effects of these two variables. ITAMPR data are reported for approximately 330 normal-hearing children who were entering first grade, but were otherwise unselected. Lack of significant associations between rate and memory thresholds and several measures of language development suggests that auditory temporal processing and auditory memory, as measured by the ITAMPR, are not primary factors in language skills or disorders. [Work supported by Indiana University and the Benton County School Corporation.]
Fifty years in (psycho)acoustics: Some conclusions
Authors: Plomp Reinier
Published: July 2002

The exceptional honor of this session gives me the opportunity to introduce some questions usually not discussed in conferences papers. My point of departure is that the function of our hearing is to inform us as reliably as possible about the world of sounds around us. It is the task of hearing research to find the laws involved. In carrying out this task, we are permanently confronted with several temptations. Their common origin is the scientific rule to keep the number of variables as small as possible. In this way, parts get more attention than structure. Hence, many essential aspects of everyday sounds had to wait surprisingly long before they got proper scientific attention. Some examples will be discussed under the following headings: (1) the temptation to study the perception of isolated sound elements such as single tones and vowels rather than the dynamic spectrotemporal patterns of connected speech; (2) the temptation to consider hearing primarily as ‘‘designed’’ for perceiving sounds from a single source rather than from two or more simultaneous sound sources; (3) the temptation to restrict our attention to the auditory parameters of sounds rather than including cognition as an essential complementary part of hearing.
The reduction of structure-borne road noise by active noise and vibration control
Authors: Sas Paul , Dehandschutter Wouter
Published: July 2002

In this work, the feasibility of active structural and acoustic control of structure-borne rolling noise in a passenger car is demonstrated. A full vibroacoustical analysis of the demonstrator vehicle was carried out, in order to characterize fully the on-road behavior (coherence analysis, operational force analysis, and transfer path analysis), as well as to derive the necessary input/output models. The results of these analyses have been used as input for the actuator design and the control configuration determination (reference signals, actuator number and location, feedback signal determination). Different control configurations have been investigated and tested by means of numerical simulations and laboratory tests. Two control configurations, each using a different kind of control source, have been retained: a structural acoustic control system which works with six inertial shakers positioned at the main vibration transmission paths of the car suspension, and an antinoise system with four loudspeakers inside the cabin. A new inertial actuator based on the moving coil work principle has been designed and realized. A broadband control system based on an adaptive feedforward control system using six reference signals, 6/4 actuators (ASAC/ANC), and four error signals has been implemented and tested in the demonstrator car.
A functional neuroimaging comparison of the neural processing of speech and signal correlated noise
Authors: Scott Sophie , Wise Richard , Mummery Cath , Ashburner John
Published: July 2002

Functional neuroimaging affords unique insights into the neural activity of intact human brains. In previous studies, presenting speech to subjects without an explicit task demand (so-called ‘‘passive’’ listening) produced strong activations in bilateral dorsolateral temporal cortex (DLTC) that is both extensive and symmetrical [Wise et al., Brain 114, 1803–1817 (1991)]. Thus such results support the hypothesis that the DLTC of both hemispheres is involved in the acoustic and phonological processing of speech. This is contradictory to conventional understanding that the left temporal lobe, particularly Wernicke’s area, is responsible for speech identification and recognition. A study using positron emission tomography was performed which aims to contrast speech processing with a similarly complex signal; speech- and signal-correlated noise analog were presented in a listening task. Correlations specific to speech stimuli were located symmetrically in anterior regions of both superior temporal sulci. The only asymmetry waas a left-lateralized response to speech in the posterior superior temporal sulcus, corresponding closely to structural asymmetry on the subjects’ magnetic resonance images. These results are discussed in relation to the role of the right hemisphere in recovery of speech comprehension after left hemisphere-damage.
Contribution of articulatory kinematics to visual perception of stop consonants
Authors: Hall Michael D. , Green Jordan , Moore Christopher A. , Kuhl Patricia K.
Published: July 2002

Little is known about visual cues that are critical to the accurate categorization, and perceived quality, of individual phonemes. The current study provided a preliminary evaluation of the relationship between orofacial movements and visual perception of phonemes distinguished by place of articulation. A female talker produced VCV utterances for /b/, /d/, and /g/ consonants; a natural range of variation was obtained by producing each consonant in several vowel contexts. Peak displacement, peak closing velocity, and peak opening velocity were measured from the upper lip, lower lip, and jaw. Observers identified place and rated the perceived quality, or goodness, of each token as an example of the consonant category (1=poor,7=good). As expected, observers identified bilabials with near-perfect accuracy, whereas they often confused alveolars and velars. More importantly, kinematic variation affected category goodness, particularly for /b/. Linear regression analyses indicated that goodness ratings within the /b/ category were highly correlated with lower lip and jaw displacement. In fact, articulatory displacement predicted these goodness ratings more effectively than did vowel context. Implications for understanding visual place cues are discussed. [Work supported by NICHD.]
Research on the acoustic features of stutterer’s voices for the purposes of computer animation
Authors: Smol/ka Elżbieta
Published: July 2002

This paper deals with computerized visual echo, by means of which an animated image of lips speaking in chorus with the stutterer is provided. The computer animation is based on identifying the acoustic features of the Polish vowels. Only two parameters and identifying map could be made and with its help the area of each vowel occurrence could be determined. Then every area was assigned the characteristic image of lips that is typical of articulation of the vowel connected with this area. Three identifying maps are needed–for male voices, female voices, and children’s voices. They were elaborated on the basis of examination of 30 correct speaking people. Attempts were made at identifying vowels uttered by 12 stutterers on the basis of maps created earlier. For the stutterer’s voices the results of identification range around 70%. However, too small a group was examined to draw definite conclusions. Therefore, similar investigation will be continued, so as to finally confirm the applicability of computerized visual echo to stutterer’s therapy.
A statistical analysis of acoustical detection and tracking of small jet aircraft
Authors: Adams Roy , Wilson D. Keith , Srour Nassy
Published: July 2002

Ground-based networks of acoustical arrays can be used to track the location of moving ground vehicles and flying aircraft. In this paper, a method is proposed for simulating the statistical accuracy of location estimates derived from array networks. The method is based on combining Cramer–Rao lower bounds for the bearing accuracy of the individual arrays, by using a general stochastic inverse formulation. Environmental phenomena associated with acoustic propagation, such as refraction by wind and temperature gradients, ground interactions, terrain masking, and signal coherence degradation by turbulence, are included in the calculations. Issues unique to sources moving at high subsonic Mach numbers, such as source radiation patterns and propagation delays, are discussed. The statistical analysis is compared to measurements made at Fort Bliss (Texas) on a small, jet-powered drone aircraft flying at 1000 feet above ground level. Differences between radar (truth) and acoustical tracking data are compared to the simulation-based predictions.
Wave scattering in underwater acoustics
Authors: Schmitt Francoise , Daout Franck , Siohan Emmanuel
Published: July 2002

In underwater acoustics it is necessary to take into account the wave scattering by the seafloor. For example, on sonar pictures the speckle noise proceeds from the constructive and destructive interferences between al-lthe waves reflected by the elementary scatterers. The origins of this phenomenon are seafloor roughness and its acoustic properties, wave incidence, frequency, multiples reflections, the dimensions of the insonified surface, etc. The aim of this study is to characterize the scattering of waves exclusively from the roughness. Thus a hypothesis of perfectly reflecting surface is taken. Moreover, specific-geometry periodic surfaces are considered to take into account the multiple reflections and the shadow area easily. Finally it is supposed that the roughness and the wavelength are of the same size. The models to describe the scattered field are based on Kirchhoff’s theory and on Fraunhoffer’s diffraction theory. Some experiences in the acoustic tank yield good agreement between theoretical and experimental results. They show that the orientation and the area of the insonified and observed surfaces are parameters for the scattering angles and for the relative scattered amplitudes.
Noise propagation in open-plan space with barriers
Authors: Duboc Marilda , Slama Jules G.
Published: July 2002

Open-plan spaces have, in general, the distance between the floor and the ceiling much smaller to the other dimensions. This feature permits modeling sound propagation using the image source method, considering only reflection on the ceiling and the floor, which are represented by two infinite parallel planes. This paper presents some results of a computation simulation developed to represent this model. The computation program calculates the sound pressure level and the insertion loss in an open-plan space in the presence of a barrier and of a belt of absorbing material placed to the ceiling over the barrier and permits simulation of the conditions of a test method specific of open-plan spaces, the ASTM-Designation E 1111 (Standard Test Method for Measuring the Interzone Attenuation of Ceiling Systems). The results show the existence of points of weak insertion loss in the shadow zone and that a belt of absorbing material on the ceiling permits the increase of the barrier efficiency. For validation of the computation method, a comparison was made with a Kuttruff model [H. Hatanaka et al., Inter-Noise (July 1995), pp. 743–746], for the simple case without barrier and belt of absorbing material. The results have presented a good agreement.
Speech intelligibility in primary school classrooms
Authors: MacKenzie David J.
Published: July 2002

Recent research has highlighted the growing problem of noise levels in classrooms. The speech intelligibility of 60 occupied primary school classrooms has recently been investigated: high noise levels, long reverberation times, and poor classroom design are but some of the problems encountered. The recommended %ALcons should be 5%, whereas in some modern classrooms the value was 100%. The shape of the classroom, as well as the materials used, can lead to locations within the classroom where the quality of speech heard can be poor. Measurements were carried out in classrooms before and after acoustic treatment: the speech intelligibility in treated classrooms improved noticeably. Throughout the research project children have been involved with the majority of the measurements, with their opinion being sought and listened to. The results have been used to tackle problems of poor acoustics in local schools and also in the appraisal of two new academic buildings to be constructed in Edinburgh. These buildings are for the education of children who are either hearing impaired or have a language difficulty. The design of the buildings has been carefully considered as well as the materials being used and the correct criteria for classroom acoustics.
The transmission beam pattern and echolocation signal of the harbor porpoise (Phocoena phocoena)
Authors: Au Whitlow W. L. , Kastelein Ronald A. , Rippe H. Tineke , Schooneman Nicole
Published: July 2002

The transmission beam pattern of an echolocating harbor porpoise (Phocoena phocoena) was measured in both the vertical and horizontal planes. An array of seven Brüel & Kjaer 8103 hydrophones connected to an amplifier-line driver module and a Racal Store-7 instrumentation tape recorder which was operated at 30 ips (76 cm/s). The porpoise was trained to station in a hoop and echolocate a cylindrical target located at a range between 7 and 9 m while the array was located 2 m in front of the hoop. The beam in the vertical plane was pointed forward with a 3-dB beamwidth of approximately 19 degrees and the beamwidth in the horizontal plane was approximately 16°. The individual hydrophones in both the vertical and horizontal arrays measured signals that were similar in shape throughout the 40-degree span of the array. The porpoise emitted clicks with interclick intervals that were greater than the round trip travel time between the animal and the target by 20 to 35 ms. Histogram of source level, peak frequency, and bandwidth are also presented. The average source level, peak frequency, and bandwidth were 157 dB, 128 kHz, and 16 kHz, respectively.
The comparison of inverse filtering techniques applied together with fractal analysis in the sea bottom recognition
Authors: Lubniewski Zbigniew , Moszynski Marek , Stepnowski Andrzej
Published: July 2002

The results of the combined approach using fractal analysis and inverse filtering methods applied to sea-bottom-type recognition are presented. The single-beam one-frequency echosounder was used in described investigations. The bottom-scattering impulse response was used to extract descriptive parameters of a seabed type. Both direct methods, including windowed SVD, regularization and wavelet analysis, as well as iterative techniques like maximum entropy, and expectation, maximization, and smoothing (EMS) were investigated. The data were acquired from acoustics surveys on Lake Washington and Liberty Bay. The results were compared and discussed especially in the context of excessive smoothing of the extracted fractal features by applied newly developed inverse techniques.
Seafloor scattering: Modeling and analysis of classification clues
Authors: Ivakin Anatoliy N.
Published: July 2002

Possibilities of scattering data inversion for various seabed properties are analyzed using recently developed models of acoustic bottom interaction. Different scattering mechanisms are considered giving the main contributions to total bottom scattering which are due to different types of medium irregularities: volume inhomogeneities of the sediment medium and roughness of its surface and internal interfaces. High-frequency model of scattering corresponds to sufficiently strong absorption and small penetration into the sediment such that the influence of seabed stratification is negligible. At lower frequencies, a layered seabed scattering model considers also refraction and interference effects due to sediment stratification as well as effects of elastic scattering and reflection from the basement supporting both compressional and shear waves. Frequency-angular dependencies of the scattering strength for both monostatic and bistatic cases are calculated and analyzed for various seabed types. Distinctive features are discussed which can be used as classification clues for determination of various parameters of the seafloor. Additional clues are revealed from an analysis of the spatial correlation function of the scattered field that can be used for distinguishing and/or separating the volume and roughness components of scattering.
Effect of increased ambient pressure on lithotripsy-induced cavitation in bulk fluid and at solid surfaces
Authors: Bailey Michael R. , Cleveland Robin O. , Sapozhnikov Oleg A. , McAteer James A. , Williams James C. , Crum Lawrence A.
Published: July 2002

By reducing cell damage but maintaining stone comminution, overpressure (OP)—increased hydrostatic pressure—offers the promise of safer more effective shock wave lithotripsy (SWL) [Delius, UMB 23, 611–617]. A current hypothesis is that stones offer cavitation sites—sites of violent bubble activity—when the cavitation nuclei in a free field have been dissolved into the fluid by overpressure. Cavitation around solid bodies and in a free field with and without overpressure is investigated. High-speed photography and dual passive cavitation detection (PCD) were used to measure the temporal and spatial extent of cavitation in a 10-cm3 plastic chamber that minimally altered the shock wave. In a free field at OP=0 atm, cavitation bubbles formed and collapsed in 280±20 μs. The time of collapse tc was halved at OP=1 atm, and cavitation activity was not detectable at OP=3 atm. With a stone present, a bubble ∼10 times larger than free-field bubbles grew on the surface of the stone and collapsed after 440±50 μs. With overpressure tc shortened cavitation was still measurable (tc=80±12 μs at OP=3 atm). Results were similar with human kidney stones, artificial cement stones, and an aluminum plate, and support the caviation hypothesis. [Work supported by NIH DK43881, FIRCA, and CRDF.]
Clinical evaluation of cavitation thresholds in patients undergoing lithotripsy
Authors: Coleman Andrew J. , Verma Prashant K. , Cahill Mark D.
Published: July 2002

Thirty patients undergoing extracorporeal lithotripsy for renal and uteretic stone disease were included in a study of cavitation thresholds. A passive, focused hydrophone was used to detect the 1-MHz component of the broadband noise emmission from bubbles generated at depth in tissue close to the focus of a Stortz Monolith SL20 lithotripter. A theoretical model was used to obtain predictions of the peak negative pressure at the focus of the lithotripter at output settings corresponding to those used clinically. A detectable cavitation threshold was identified in 18 patients. As the output level of the lithotripter is reduced, multiple bubble collapses cease to be detected below a well-defined threshold which is similar in all patients. There is also some evidence that this threshold is dependent on the previous exposure history of the tissue. [Work supported by MRC.]
Array technology for binaural hearing aid applications
Authors: Merks Ivo L. D. M. , Boone Marinus M. , Berkhout A. J.
Published: July 2002

An increasing number of people have great difficulties in understanding speech in noisy environments. These difficulties can be resolved with a directional microphone array which attenuates the background noise while it transmits the desired signals unaltered to the hearing aid. A highly directional endfire array has been developed containing only four omnidirectional microphones which are integrated into the arm of a pair of spectacles. Two endfire arrays, one per ear, devise a binaural hearing aid which further increases the speech intelligibility and also enables localization. The arrays realize maximum directivity with a least-squares optimization of the array processing which also takes into account the diffraction effects due to the presence of the head. The microphone signals are processed with FIR filters to obtain maximum control over both the amplitude and phase of the transfer functions of the filters, thereby achieving maximum directivity. The microphone array attenuates the background noise of a diffuse sound field from 5 dB at 500 Hz to 10 dB at 4 kHz. The improvement in speech reception threshold (SRT) of 16 normal hearing and 26 hearing-impaired subjects will be measured and presented in this paper.
Hot new topics in ASA/ANSI standardization
Authors: Schomer Paul
Published: July 2002

The ASA Committee on Standards has many new work efforts underway. As chairman of the ANSI S12 committee (noise), this author is primarily versed in the hot new noise standards being developed. Hence, this paper will concentrate on noise standards. (The S12 committee can be considered the counterpart to ISO TC 43/SC 1 and concentrates on noise.) Several new efforts are underway in S-12, including (1) classroom acoustics, (2) room noise criteria, (3) model community noise ordinances, (4) community noise assessment, (5) consumer product noise labeling, and (6) in situ hearing protector measurements. In addition, there is a new effort in the S-3 committee (bioacoustics) dealing with warning signal definitions. Clearly, these new topics depart from many of the traditional standards topics such as measurement of workplace machinery noise or office and business equipment noise. Rather, these new work efforts concentrate on criteria development, measures to assess response to noise in various settings, or various human interactions with sound, etc. Several of these topics, such as community noise assessment, noise labeling, or hearing protector measurement, relate to ongoing international efforts. This paper will briefly describe the goals, progress, key contacts, and schedules for these work efforts.
Multidimensional scaling of musical timbre constrained by physical parameters
Authors: McAdams Stephen , Winsberg Suzanne
Published: July 2002

A new multidimensional scaling technique [S. Winsberg and G. De Soete, Br. J. Math. Stat. Psychol. 50, 55–72 (1997)] is applied to the analysis of dissimilarity judgments on musical timbres in both group and individual data. This technique constrains the resulting spatial model such that the order of items along a given perceptual dimension preserves their order along a previously established physical dimension. The fit between perceptual and physical dimensions is achieved with spline functions and yields what may be interpreted as the auditory transform of the physical dimension needed to obtain the perceptual one. A reanalysis of ten timbre spaces from the literature shows that this kind of model does not work as well on group data as it does on individual data due to differences in the nature of underlying dimensions and in the form of the auditory transforms for different listeners. Further, an analysis of individual data sheds light on the reasons why higher dimensions in published timbre spaces are so often difficult to interpret.
U.S. Air Force research on military aircraft noise and its effects
Authors: Finegold Lawrence S. , Lee Robert A. , McKinley Richard L.
Published: July 2002

For over half a decade, the U.S. Air Force (USAF) has been conducting a program of research on military aircraft noise and its effects. This paper provides a brief overview of some of the major projects implemented at Wright-Patterson Air Force Base in the past decade on noise measurement and monitoring, noise propagation modeling, and the effects of noise on humans, animals, and structures. It also includes both sonic boom research and subsonic aircraft overflight noise. Several international collaborative efforts have been conducted with NATO partners on both fixed-wing aircraft and helicopter overflight noise. In addition to the community noise portion of this program, the USAF has also conducted research on the auditory effects of military occupational noise exposure, development of hearing protection devices, and the development of three-dimensional audio information presentation. Although time limits preclude a comprehensive review of the extensive USAF program, highlights of some of the most interesting and important projects will be provided.
Modeling of military aircraft noise in support of environmental impact mitigation
Authors: Standen Neil M. , Humphries Gary W.
Published: July 2002

The Military Training Area in Labrador, Canada is used by NATO Alliance air forces of the United Kingdom, Germany, and the Netherlands, and is managed by the Canadian Department of National Defence (DND). Protection of the natural environment is a major consideration in the management of the training area. This paper describes a computer-based noise propagation model that will be used to support environmental management. The paper demonstrates its use in planning flying training sorties to mitigate short-term environmental impacts, and also its use in assessing environmental effects of the flying activity over the longer term. The model enables DND to maximize the extent of the range available for flight training by accurately calculating noise levels on the ground, and hence the degree and method of noise impact mitigation that is appropriate. The noise propagation model is used in conjunction with other computer-based tools for flight track modeling, terrain modeling, and specifying locations of noise-sensitive areas (typically wildlife habitats which may change in location during the training period). Other projects are aimed at investigating and evaluating acceptable levels of noise impact, in terms of consequences on wildlife viability in these habitats.
Military aircraft noise and health—Methodological issues in research
Authors: Flindell Ian H.
Published: July 2002

The possibility of long-term health effects associated with prolonged exposure to military low-altitude flying (MLAF) noise in designated training areas in the UK remains an area of public concern. Definitive research in this area is difficult for many reasons. In addition to the general problems which apply to all noise and health research; of defining the effects of variables of interest; of estimating individual exposure; of independently identifying susceptible individuals; and of controlling for confounding factors, the generally low levels of MLAF noise exposure (measured as outdoors LAeq) and the wide variability of training schedules to meet varying tactical requirements create further difficulties. MLAF events are often irregular, infrequent, and may have higher maximum levels and higher onset rates than other types of environmental noise. What are the theoretical reasons why these factors should contribute to increased risks of health effects? Acoustic startle effects and associated physiological responses can equally be interpreted either as signs of healthy reactivity or as precursors of disease. MLAF events can contribute to acute annoyance at the time that they occur, but the possible mechanisms for noise-related annoyance to contribute to longer term morbidity through some vague and unspecified stress hypothesis are obscure.
Development of a noise criterion for laboratory medical instrumentation
Authors: Muto William H.
Published: July 2002

Over the past two decades, medical laboratory instrumentation has undergone a major transformation in terms of its functionality, sophistication, and degree of automation. A common complaint among laboratory professionals using these instruments has been that laboratory noise levels have increased, and that certain instruments are especially noisy. The goal for this project was to establish an instrument noise criterion that would serve as a standard for the company’s future generations of instruments. The ideal standard in this context would eliminate or greatly reduce customer complaints due to noise without significantly increasing development and manufacturing costs. After surveying various noise criteria and after preliminary investigatory studies, a variation of balanced noised criteria curves (NCB), proposed by Beranek (1989), was adopted as the basis for the standard. The current presentation will provide: (1) a description of the adopted noise criteria, (2) practical considerations for use in the current context, (3) measurement methods and tools used, and (4) a summary of progress to date regarding the use and utility of the adopted noise criteria.
Three-dimensional localization and characterization of acoustical sources in a truck cabin
Authors: Dubail Patrick , Zakharia Manell E.
Published: July 2002

In the framework of acoustic comfort, an accurate localization (in range and angles) of the sources transmitting noise to the driver was investigated. The aim of such a localization is to act on the predominant sources in priority (in a given frequency range). The sources were either vibrating ones corresponding to the excitation point, or fictive ones corresponding to complex propagation and multiple reflections on the cabin elements. An experiment has been conducted on a real cabin with a single point of excitation. The mechanical excitation was achieved via a shaker; frequency-modulated signals have been used that cover a very wide frequency range (0.03 to 15 kHz). Both active and digital corrections were used. Two crossed line arrays of 112 microphones were used for the reception, all the signals were digitized and processed later on. Standard wideband beamforming and beam steering were used on both arrays (in the time domain). For every frequency (or frequency range), the 3D localization (horizontal and vertical angle, time) of sources was achieved. The major sources (15 to 20) were isolated using the radon transform. A fine analysis was achieved in order to provide, in addition to their 3-D localization, their spectral content.
Order tracking of diesel engines with a Kalman filter
Authors: Kryniski Krystof , Carlsson Ulf
Published: July 2002

Order tracking analysis is one of the techniques used to monitor the performance of diesel engines. The objectives are to separate vibration into terms corresponding to the rotational speed and its multiples and then to monitor the changes over the revolution of a crankshaft. A Kalman filter provides the technique of isolating each of the components that are synchronous to the shaft rotation. By filtering the signal in the time domain it has also the capabilities to follow any variation of the rotational speed. Thus, the Kalman filter, if properly designed, can provide a tool for testing not only steady engine operation but can also be used to analyze both the engine acceleration and declarations under different loads. The paper discusses first, the process of monitor the frequency components locked up to the rotational speed with high resolution. Then, it shows how to reconstruct the synchronous components, in terms of amplitude and phase, to produce the vibration patter over the crankshaft revolution.
Finite-element methods applied to the propagation of acoustic wave along immersed wedges
Authors: Hladky-Hennion A. C. , Langlet P. , Bossut R. , de Billy M.
Published: July 2002

Immersed in water, wedges can generate either propagating or radiating acoustic guided waves according to the value of the apex angle. The propagation of such waves is analyzed with the help of two methods based on finite-element methods: a time analysis [A. C. Hladky-Hennion et al., J. Acoust. Soc. Am. 104, 64–71 (1998)] and a modal analysis for which an original numerical technique is suggested to describe the radiating (or supersonic) modes. The finite-element results obtained with the two methods for brass and duraluminum wedges are compared to the experimental measurements. A good agreement is observed for either subsonic or supersonic regions.
Designing electrodynamic loudspeakers by using a new computer modeling scheme
Authors: Rausch Martin , Lerch Reinhard , Kaltenbacher Manfred , Landes Hermann , Krump Gerhard , Kreitmeier Leonhard
Published: July 2002

A new technique for the computer modeling of fluid-loaded magnetomechanical transducers is presented. This numerical technique is based on a finite-element method (FEM) and allows the precise calculation of the magnetic, mechanical, and acoustic fields, including their couplings. Further on, nonlinear effects in the mechanical and magnetic behavior are considered. Therewith, the complex dynamic behavior of electrodynamic loudspeakers was studied and, furthermore, an appropriate computer-aided engineering (CAE) environment has been established. This CAE tool allows an optimization of critical parameters, for example: The validity of the computer simulations is verified with the help of appropriate measurements. The calculated and measured values for eigenfrequencies, axial pressure responses, and electrical input impedances are in excellent agreement. The applicability of the presented calculation scheme with respect to the computer-aided design of moving coil drivers is demonstrated by reporting several practical applications, which are of great interest for loudspeaker manufacturers. In the present paper, the elimination of response dips at intermediate frequencies, the calculation of polar responses, and the examination of the so-called jump-out excursion, are presented.
SAW sensor for low nitrogen dioxide concentration
Authors: Opilski Aleksander , Urbanczyk Marian , Jakubik Wiesaw
Published: July 2002

The devolopment of a technique concerning macromolecular compounds has made it possible to get thin layers that change their physico-chemical properties as a result of their interaction with the ambient atmosphere. Changes of the physical properties of specially prepared chemically sensitive layers influence the conditions of the propagation of an acoustic surface wave arranged in the layered system piezoelectric waveguide layer of the compound. Particularly, if the mass and electric conductivity of the chemically sensitive layer changed, the velocity of propagation of the acoustic wave changes. The presented paper includes a short review of the SAW gas sensor field and some experimental results for the detection of a low concentration of nitrogen dioxide in the air.
Ultrasonic study of multi-ply composites
Authors: Rokhlin S. I.
Published: July 2002

Multi-ply composites are studied ultrasonically using transmission and reflection spectroscopy and time-resolved line focus acoustic microscopy. For quasi-isotropic multi-ply composites, the ultrasonic response does not exhibit isotropic behavior as, for example, is observed in mechanical tests. The amplitudes of the ultrasonic obliquely transmitted/reflected signals depend on the sample orientation relative to the incident plane as well as top ply orientation and ply sequence. In addition to the plane-wave study, the applicability of the time-resolved line focus acoustic microscopy for determination of elastic constants of composites is discussed and the results are compared to data obtained by the self-reference double-through-transmission ultrasonic bulk wave method. A theoretical model to predict ultrasonic wave propagation in the multi-ply anisotropic structure is described. The efficiency and performance of the transfer and global matrix methods are compared. The theoretical results are compared with experiment and used to interpret the complicated wave behavior in this material.
Two-microphone noise reduction for the LAURA cochlear implant
Authors: Vanden Berghe Jeff , Wouters Jan
Published: July 2002

An adaptive noise cancellation scheme based on two-stage adaptive filtering has been developed for a two-microphone configuration in one hearing aid. This strategy has been tested with hearing-impaired listeners and yields a significant improvement of the speech reception threshold in background noise, as measured with sentences and two-syllable words [J. Vanden Berghe and J. Wouters, J. Acoust. Soc. Am. 103, 3621–3626 (1998)]. As the effect of background sounds is even more severe for cochlear implant (CI) users than for the hearing impaired in general, this strategy was tested with four LAURA CI users. The system was implemented in real time on Audallion, a portable DSP-platform for hearing aids (Audiologic-Resound-Danavox Digital Alliance), and used as a preprocessor for the input to the CI speech processor. Speech intelligibility data in noise were obtained with and without this two-microphone noise reduction algorithm. The data indicate a similar effect for CIs as for hearing-impaired and normal-hearing people. For all subjects, measurement of the SRT for the two-stage adaptive filtering strategy shows an improvement of more than 10 dB in SNR when compared to the unprocessed condition. An analysis of variance indicates this improvement to be highly significant.
Sound and vibration at low frequencies
Authors: Bellmann Michael A. , Reckhardt Carsten , Mellert Volker , Remmers Hermann
Published: July 2002

Equal-loudness-level contours are assumed to reflect the frequency sensitivity of the auditory system. Studies on equal-loudness-level contours show considerable differences even when the same measurement method is used. Recent studies [Gabriel et al., DAGA 96; Reckhardt et al., DAGA 97] report on the influence of measurement method, threshold, and choice of test tone level. In this study, an adaptive 2-AFC method [Reckhardt et al., DAGA 97; Verhey et al., DAGA 97] is used for measuring equal-loudness level contours in the frequency range of 16 to 160 Hz at 60 phon. The data are measured in a pressure chamber for 12 normal-hearing subjects. Results are higher than the standard curve specified in ISO 226. In a study of Reckhardt et al. it is shown that the interindividual variance is decreased by taking the individual threshold of hearing into account. The results from low-frequency measurements support this finding. In addition, this study investigates the influence of vibration on loudness perception. Equal-loudness-level contours are measured in the presence of distinct vibration levels above vibration threshold in a frequency range of 10 to 80 Hz.
Short and medium motor responses to auditory pitch shift: Latency measurements of the professional musician’s audio-motor loop for intonation
Authors: Parlitz Dietrich , Bangert Marc
Published: July 2002

For the singer’s voice, as well as for many musical instruments, like strings or brass, a precise intonation relies on a quick and adaptive fine-tuning mechanism, i.e., a motor response correcting for deviations of the produced tone due to mechanical properties of the body and instrument as well as due to environmental parameters. The aim of the procedure is either to be in tune with an internal representation of the correct pitch or to be in harmony with accompanying instruments or singers. In an experimental setup with a real-time audio pitch shifter and an infrared-based motion analysis system, this unique ability of musicians can be studied systematically. In a group of (a) expert viola players, (b) expert trombone players, and (c) professional singers, the distribution of pitch-shift-reaction-times (PSRTs) is measured (1) in a solo-player/singer situation and (2) in an ensemble/choir situation. Results are compared to recent studies with nonmusicians [T. A. Burnett et al., J. Acoust. Soc. Am. 103, 3153–3161 (1998)]. Similarities to other orientation reactions like saccadic eye-movements and to the rapid pitch-correcting mechanisms in the echo-locating system of the bat are discussed.
The detection of conspecific and heterospecific calls in noise by birds
Authors: Lohr Bernard , Wright Timothy F. , Dooling Robert J.
Published: July 2002

Little is known about the effects of noise on the ability of birds to detect vocal communication signals. To address this question, an operant conditioning procedure was used to test two species of birds, budgerigars (Melopsittacus undulatus) and zebra finches (Taeniopygia guttata), for their ability to detect conspecific and heterospecific calls in noise. Calls from three species, budgerigars, zebra finches, and canaries (Serinus canaria), served as test stimuli. In general, budgerigars showed lower thresholds (better detection abilities) across all call types than zebra finches. Both zebra finches and budgerigars showed a similar pattern of threshold changes for call types from different species. Calls of budgerigars were the easiest to detect, followed by canary calls, and finally zebra finch calls. Call bandwidth, which increases across species from budgerigars, to canaries, to zebra finches, may influence the pattern observed in thresholds. Low-frequency, band-passed noise simulating anthropogenic noise sources resulted in considerably less masking than broadband white noise. Generally, these results conform to the power spectrum model of auditory function. [Work supported in part by the Comparative and Evolutionary Biology of Hearing at the University of Maryland, NIDCD Grant No. DC00198 to R.J.D., the SERDP program, and the U.S. Army Construction Engineering Research Laboratories.]
Measurements of the spherical reflection coefficient at grazing sound incidence above sediment
Authors: Harms Henning , Matuschek Rainer , Mellert Volker
Published: July 2002

Liquid undissolved fluid pollutants covering the sea bottom, in general, form a thin layer of a few cm, which cannot be detected acoustically by normal sound incidence due to the small difference of impedance compared to water. Such layers, however, can strongly affect the spherical reflection coefficient at grazing sound incidence. Using broadband chirp signals, the interference pattern at the receiving hydrophone is found to provide information on the physical properties of the sediment surface and its coating. Laboratory measurements in a small water tank with flat and rippled sand sediments coated by various different chemical substances revealed a systematic dependence of the measured excess attenuation function (EAF) on the acoustic impedance of the chemical, the layer thickness and the grazing angle of the incident sound. Results of numerical modeling performed with a fast field program (fflags) show good agreement with the measurement results. In order to prove the applicability of the new detection method, measurements in shallow water will be presented. [Work supported by BMBF.]
Recent advances in coastal ocean pollution research and monitoring
Authors: Proni John R. , Nelson Terry A.
Published: July 2002

Design of both real-time studies of oceanic discharges of potential pollutants such as sewage effluent, and long-term monitoring of same, are complicated by a number of factors. These factors include lack of knowledge of the space and time distribution of the discharge plume, proper placement sites for sample gathering, and lack of knowledge of the space-time distribution of ‘‘interfering’’ plumes (plumes from sources other than the discharge plume under study). Progress has been made in the development of ‘‘integrated sensor suites’’ which produce data with substantial synergistic benefits. Ocean acoustics plays a key role in integrated sensor suite data unification. In a recent study in the coastal waters off San Juan, Puerto Rico, the ability of acoustics systems to view essentially the complete oceanic water enabled a connection to be made between salinity, temperature, and turbidity measurements gathered in the upper 5 m in the water column to a specific port of a sewage effluent diffuser. Having established the ‘‘connectivity’’ of the distal field measurement to a specific port, a dilution value at the distal point could confidently be calculated. This example is but one of many of the synergies available from utilization of multiple sensor suites unified through acoustics.
Humidity sensing properties of uncoated and coated SAW delay lines
Authors: Anisimkin V. I. , Bonfiglio A. , Caliendo C. , Verona E. , Penza M.
Published: July 2002

The relative changes in the SAW propagation velocity Δv/v were measured as a function of the relative humidity (RH) at the normal conditions. The results of the measurements were compared for different bar substrates (AT,x-, ST,x-, yx-SiO2, yz-, 128° y,x-LiNbO3) and different coatings deposited on these substrates (polyvinyl alcohol, Pd, Pd0.99Ni0.01, Pd0.97Ni0.03). In accordance with theoretical predictions [V. I. Anisimkin and E. Verona, IEEE Trans. Ultrason. Ferroelectr. Freq. Control 45(5), 1–8 (1998)], the behavior of the Δv/v(RH) curves for a given coating was found to be dependent on the material of substrate and its crystallographic orientation. The magnitudes Δv/v for uncoated SiO2 were two to ten times larger than those were for uncoated SiO2. The coating of the substrates by polyvinyl alcohol and Pd increased sensitivity of SAW towards humidity by 30 to 100 times, providing large response Δv/v≊100 ppm even at small RH≊1%. The threshold concentration for the coated SAW devices was estimated as RH≊0.01%.