bluuebunny/crossref_metadata_2025 huggingface dataset:
Refining mapping strategies to improve the sound quality of physically controlled synthesis
Authors: Verfaille Vincent , Rebillout Arnaud , Guillemain Philippe , Wanderley Marcelo M.
Published: May 2008

A new technique, called 'physically controlled synthesis', is being developed to improve the controllability and sound quality of digital sound synthesis. It can be seen as a mapping strategy that combines a synthesis model based on a physical model (controllability) with a signal model based on additive synthesis (sound quality), and a database of pre-analyzed natural instrumental sounds. A key point is the computation of perceptually relevant timbre descriptors that interface the two synthesizers to provide additive synthesis data by navigating the database and selecting neighbour additive frames to morph. To limit the latency introduced, we developed specific algorithms to extract sound features from the physical model; the database size was increased offline by using a higher control sampling rate. In addition to previous works by the authors, devoted to the permanent regime and using a 2D indexation of the additive database, transients handling is achieved through a 3D search in a frame-by-frame basis that ignores the natural time unfolding, hence allowing to choose the best frame with the proper pitch in addition to the two other sound descriptors.
Experimental modal analysis of bows
Authors: Ravina Enrico , Silvestri Paolo , Airenti Antonino
Published: May 2008

The vibration performances of bow instruments are usually studied developing numerical and experimental modal analyses of the body of the instrument or of their parts (tailpiece, bridge, fingerboard, neck). The dynamic contribution of the bow is less considered, but the mutual actions generated between bow and strings are conditioned by the mechanical features of the bow. The paper analyzes the dynamic behaviour of different kind of bows (clip-in frog and screw-driven frog) and different geometries (baroque, modern,...) through experimetal modal analyses. Bows are instrumented with micro-accelerometers and excited by a micro-hammer. Frequency Response Functions up to 2500 Hz allow a good characterization of the bow and show significant differences about the modal shapes. The study is integrated with the experimental strain analysis, based on micro strain gauges glued on the body; the very small dimensions of the transducers (2.5 mm) allow, from one side, a not intrusive analysis but, from another side, require specific contrivances of mounting. Details on the integrated experimentations are focussed and discussed.
Study the mouthpiece of the txistu
Authors: Agos-Esparza A. , Elejalde-García M. J. , Macho-Stadler E.
Published: May 2008

The txistu is a three finger holed recorder from the Basque Country. The evolution of the txistu involves different kinds of wood, bore length, finger hole positioning and it being made of two or three pieces. The txistu also has a unique mouthpiece, made up by a small metallic piece of the pipe and also a metal reed which was introduced centuries ago. The distance between the pipe and the reed can be adjusted to fit the user's preferences. By using a blowing machine and data acquisition software, experiments study the influence of the shape and inclination of the reed on the values of the harmonic content and the sonority of the final note.
Source-resonator modeling: a rough paradox
Authors: Millot Laurent P.
Published: May 2008

Using the example of a short pipe loaded by a free reed located upwards, we will underline the fact that a reflection function based modeling will not give the same results (and synthesized sounds) as an unsteady incompressible and lossless Bernoulli description while this model is commonly assumed to be a low-frequency limit case of the first one, and that the second description is the only valid one. This paradox will be explained and it will be underlined why the so-called electro-acoustical analogies do not constitute a low-frequency limit case of reflection function or input impedance descriptions, based on a waves paradigm. Extension to striking reeds and/or longer pipes, as found in saxophone, clarinet or sheng for instance, will be discussed and a strange coupling between a priori incompatible models, commonly used in Musical Acoustics notably, will be described.
Active Sound Design of a Bassoon
Authors: Konkel Frederic , Jakob Andre , Heintze Frank , Möser Michael
Published: May 2008

Possibilities of influencing the sound characteristics of a woodwind by means of active noise control were investigated. The woodwind used in this investigation was a bassoon. The first step of the investigation consisted of a set of measurements of the sound spectra of different tones and volumes by means of measurement microphones inside and outside the instrument. Additionally measurements of the radiation characeristics of the instrument were performed by means of the acoustic camera. An experimental setup was designed with the instrument driven mechanically by compressed air. The aim of the work was to change the sound characteristics of the bassoon by changing individual harmonics of the tones by means of a loudspeaker attached to the bassoon. The loudspeaker was attached to the bassoon via a tube. Suitable positions for the connection of the tube to the instrument were examined as well as suitable possibilites for the generation of the reference signal neccessary for the feedforward control scheme. The experimental setup will be presented here as well as results of the measurements with and without active sound design with an analog controller.
Simulation of Acoustic Pressure and Flow Velocity in Human Glottis
Authors: Sidlof Petr , Chaigne Antoine , Doare Olivier , Cadot Olivier
Published: May 2008

The pressure and velocity fields in coronal plane along the vibrating vocal folds were studied using a finite element mathematical model. The shapes of the vocal folds were specified according to data measured on excised human larynges in phonation position. The mathematical model of the flow is based on 2D incompressible Navier-Stokes equations adapted to deal with the time-variable shape of the domain, caused by vocal fold vibration. The numerical simulations allow to observe closely various flow features related to phonation - flow separation in the glottis, Coanda effect or vortex shedding. The numerical results were verified experimentally by Particle Image velocimetry (PIV) on a physical vocal fold model. In addition to acoustic, subglottal pressure and impact intensity measurements, flow velocity fields were recorded in the domain immediately above glottis. Analysis of the PIV images gives good insight into the dynamics of the supraglottal flow. Among other applications, the results should be used in the future for singing voice simulations based on physical models.
Recent research activities for the assessment of vibration in living environment with respect to human perception in Japan
Authors: Matsumoto Yasunao , Kunimatsu Sunao , Ishikawa Takashige , Hirao Yoshihiro
Published: May 2008

The number of complaints against vibration has been increasing gradually in recent years in Japan. This fact may imply problems of the Vibration Regulation Law that was implemented almost 30 years ago so as to regulate vibrations caused by factories and construction works and to mitigate vibration problems caused by road traffic. A group of experts has been investigating an assessment method that may be able to assess recent vibration problems reasonably since 2004. This paper presents a part of group activity that aims at improving the understanding of human vibration perception and applying it in vibration assessment in living environment. Results obtained from experiments involving human subjects to determine perception thresholds of whole-body vibration are summarised.
Development of a social survey questionnaire of reactions to vibration in residential buildings
Authors: Howarth Henrietta , Griffin Michael J.
Published: May 2008

A social survey questionnaire has been developed to determine human responses to vibration in residential environments. The overall aim was to produce a robust methodology for obtaining responses that could be combined with vibration measurements so as to investigate dose-response relationships for vibration in residential buildings. The vibration considered included that from sources outside the control of residents (e.g., road, rail, industrial, construction). This paper describes the development of the questionnaire and explains its structure and content. A review of social surveys and field and laboratory studies of vibration and noise is included. Methods of analysing responses obtained to the questionnaire are summarised.
Describing the sound environment of the neurological intensive care unit and personnel response
Authors: Ryherd Erica , Persson Waye Kerstin
Published: May 2008

The hospital soundscape is populated with a number of noise sources that may be detrimental to the occupational environment, including medical equipment, alarms, portable carts, activities, paging/communication, and ventilation systems. This paper describes a study in which sound measurements were made over five days and occupant evaluations were conducted in a neurological intensive care unit (ICU). Forty-seven nursing staff members completed questionnaires regarding general reactions to the ICU environment as well as perceived psychological and physiological reactions to the noise. Acoustical characteristics such as level distributions, restorative periods, and spectral content were explored in addition to overall equivalent, minimum, maximum, and peak sound pressure levels. Results showed the mean length of restorative periods (LAeq below 50 dB for more than 5 min) was 9 and 13 minutes for day and night, respectively. Sound measurements near the patients showed LAeq values of 53 - 58 dB, and dosimeters worn by the personnel revealed higher noise levels. Questionnaire results indicated that 91% of those surveyed felt that the noise negatively affected them in their daily work environment. They perceived the noise as contributing to stress symptoms such as irritation, fatigue, tension headaches, and difficulties concentrating. [Work supported by ASA and Swedish FAS].
Indoor environment and acoustic conditions in two Finnish hospital wards
Authors: Haapakangas Annu , Helenius Riikka , Hongisto Valtteri O.
Published: May 2008

The aim of this study was to determine the acoustic conditions of two typical Finnish wards. The methods included long-term noise measurements, building acoustical measurements and questionnaires for patients (N=33) and nurses (N=27). The average sound pressure levels were within 49 and 58 dBA in the corridors, office and patient rooms. Personal noise exposure levels among nurses were within 56 and 70 dBA. The noise was mainly caused by people. Ventilation noise level was 28 dBA. Building acoustic measurements showed reasonable agreement with national directions. Indoor environment was not a problem for most patients. Some disturbance from thermal conditions, dry air and noise was experienced. From daytime noise sources, other patients' snore and groans caused annoyance in some patients. Night-time sleep was disturbed most by anxiety, pain, noise, thermal conditions and an uncomfortable bed. Patients were, on average, quite satisfied with the overall room conditions. Nurses were more bothered by environmental factors than patients, giving highest annoyance ratings to thermal conditions, air quality and noise. Noises were experienced to cause some distraction when concentrating to work tasks. Sounds of phones ringing were experienced as particularly detrimental. Lack of privacy was the most obvious problem in both staff and patient evaluations.
The ranking of rolling noise from passenger car tyres - a comparison between measurements and modelling results
Authors: Berge Truls
Published: May 2008

Tyres are type approved with regard to rolling noise on an ISO-test track, according to the EU-directive 2001/43/EC. The test track is basically a rather smooth road surface with maximum chipping size of 8 mm. However, most surfaces normally used on roads, especially in the northern European countries, are rougher surfaces, typically Stone Mastic Asphalt (SMA) with 11 to 16 mm stones. A project has been initiated to compare the noise levels of a selection of highly used after market summer tyres (in Norway). Noise measurements of 12 tyres have been performed on a selection of new and old SMA-road surfaces. The 3D texture of the same road surfaces has been measured with laser profile equipment. In addition, the point mobility and other design features of the tyres have been measured to be used as input data to the SPERoN tyre/road noise model. Then, comparison will be made between measurements and modelling results. Preliminary results from the noise measurements show a difference of 2.5-3 dB(A) on SMA-surfaces, between the tyres. The project is a co-operative between SINTEF (Norway), MüllerBBM (Germany), and Chalmers University (Sweden).
Sound Radiation Modes of a Tire on a Reflecting Surface
Authors: Bolton J. Stuart , Yum Kiho
Published: May 2008

Wave number decomposition of a tire's radial vibration can be used to reveal the wave propagation characteristics of tires. In this paper, the relationship between the structural wave propagation characteristics of a tire excited at one point and its sound radiation is considered. The sound radiation resulting from structural vibration of a tire in contact with the ground was investigated by using boundary element analysis. In particular, the orthogonal radiation modes of a tire in the presence of a reflecting surface, along with their radiation efficiency characteristics, were calculated by applying an eigenvector analysis to the tire's radiation resistance matrix. The latter analysis made use of acoustic transfer vectors and a recovery surface appropriate for a pass-by noise test. The radiation mode results reveal that it is the vibration in the region close to the contact patch that primarily controls sound radiation. In particular, to reduce pass-by noise levels, it is necessary to mismatch the tire's structural ring mode and the radiation modes with high radiation efficiencies. It has also been found that the radiation from a tire is controlled by a relatively small number of radiation modes (although the number of contributing modes increases with frequency).
Simulation of tire tread block dynamics with respect to complex contact phenomena
Authors: Gäbel Gunnar , Moldenhauer Patrick , Kröger Matthias
Published: May 2008

Vibrations of the tire structure are caused by the interaction between the rolling tire and the road surface. The tread block is the only tire component which is directly in contact with the cleft road surface texture and therefore of special interest. The contact due to the rough surface leads to complex contact phenomena e.g. friction characteristics depending on normal contact pressure and relative velocity, non-linear contact stiffness and wear effects changing the tread block geometry and in hence the local contact forces. These contact phenomena strongly influence the dynamical behaviour of the tread block and the whole tire. A modular model based on a modal reduction method will be presented to investigate the tread block dynamics under consideration of the local friction characteristic, the non-linear contact stiffness and wear which are also analyzed experimentally on a concrete road surface to identify the model parameters.
Acoustical Parameters of Automotive Interiors using Hybrid Fleeces basing on natural fibres
Authors: Koenig Christian R. , Müller Dieter H. , Thoben K.-D.
Published: May 2008

Hybrid fleeces are often used to produce composites and layered structures for car interiors. The fleeces consist of reinforcement fibres and polymeric fibres as matrix material. The utilization of natural fibres as a reinforcement for composite may be regarded as an emerging research area in polymer science. An important range of application can be found in the automotive industry. Despite of ecological gains like less environmental impact of the later product within the formation, usage and disposal period further technical and economical advantages result from this strategy. In addition to a reduction of the component's cost and net weight or an improvement of driving safety due to the crash behaviour of the composite material, natural fibre reinforced polymers offer increased recycling capabilities over conventional polymers used in that area. The presentation concentrates on the possibilities by using different materials, different ratios of thermoplastic and natural fibre material and different process parameters. Layers are especially investigated to demonstrate how the fleeces and the techniques to bond the fleeces can influence the acoustical behaviour and mechanical properties. Based on the results of the measurements optimised, multi-layered sandwiches were developed and will be presented.
Structure borne noise inside a coach
Authors: Berasategi Joanes , Galfarsoro Unai , Elejabarrieta María Jesús , Insausti Igor
Published: May 2008

Nowadays the use of coaches as ground collective transport is generalizing in society and besides, its use is encouraged by all public institutions. Users of this type of vehicles request that they are comfortable, even more in long trips. Therefore, decreasing noise and vibrations inside the coach is a essential requirement to obtain a good quality of the vehicle and the satisfaction of the traveller. To increase the vibroacoustic comfort it is necessary to know qualitatively and quantitatively the noise and vibration sources, as well as their transmission paths. Thus, in this work a procedure has been defined and applied to measure and analyse the vibration and acoustic behaviour of a coach in different operating modes: idling, three constant speeds, acceleration and deceleration. 32 acceleration and sound pressure signals have been acquired, corresponding to different interior and exterior points of the coach. The analysis of the acceleration autospectra has allowed to determine the contribution of elements like floor, glasses and lateral panels to the sound pressure perceived by the traveller in the passenger compartment in the different studied operating modes.
Nanotechnology research facility- A vibration and noise control design case study
Authors: Evans Jack B. , Himmel Chad N. , Kupersztoch Daniel J.
Published: May 2008

Vibration and noise control would be critical to the success of a proposed nanotechnology and molecular research facility. Roadway traffic, a nearby power generation plant and buildings in the vicinity were potential sources of ground borne vibration disturbances. Mechanical equipment, occupant installed support apparata and occupant activities were potential sources of internally generated vibration disturbances. On-site ground borne vibration was measured for comparison with generic floor vibration criteria for sensitive installations. Results were analyzed relative to criteria for potential disturbance of sensitive equipment, perception by occupants, audible radiated structure borne noise in acoustically sensitive spaces and resolution-degrading motion for scanning and for transmission electron microscopes and other nanotechnology clean room equipment. Design guidelines and structural vibration control concepts were recommended to the structural engineers, including de-tuning, damping and isolation methods. Recommendations were provided for mechanical noise control and vibration isolation. Architectural noise control, sound isolation and room acoustics guidelines were provided for research, office and meeting spaces. This case study will discuss the desired vibration and noise control objectives and the design solutions that were implemented. Building photographs will be presented. Post-construction measurement results will be graphically compared with pre-construction conditions to demonstrate apparent degree of success in mitigating vibration.
Who can guaranty compliance with the Exposure Limit Value of 87 dB(A)
Authors: Krajcarz Fabien
Published: May 2008

The level of daily exposure (Lex8h) of workers has to be measured in accordance with French standard NFS 31084. The attenuation of personal noise protection has to be determined according to standard NF EN ISO 4869-2. In addition to the difficulties of applying these methods, one has to be aware that the actual effectiveness of the protection can deviate considerably from its theoretical effectiveness and, ultimately, it is the effective duration of wearing the protection that really determines the protection of workers. We have provided modest evidence, more than a survey in the strictest sense of the term, of the conditions in which the protectors are worn (or not) at a large French industrial company. The results have shown that the wearing of hearing protectors is far from being routine, even when the noise levels are high. Thus, the question then arises as to the guarantee which the entity or person responsible for measuring bears for compliance with the Exposure Limit Value of 87 dB (A), when wearing the protection.
A rational approach for regulating windturbine noise
Authors: Van Den Berg Martin
Published: May 2008

Windturbines have evolved from the cosy, wooden Dutch windmill type to large industrial generators of sustainable energy. Their noise production luckily did not evolve in step, but in some cases they can be a perhaps unsustainable nuisance for population living nearby. Presently the local and national authorities are trying to get a hold on the problem, often still using methods from the wooden machine age. The paper describes a modern approach for dealing with windturbine noise, using harmonized methods and recently acquired insights in the reaction of people to this particular noise. Tentative dose-effect relations in terms of Lden and Lnight enable comparisons with noise from transport.
Hand-arm equal sensation curves for steering wheel translational and axial vibration
Authors: Sauvage Mickael , Gressant Elise , Lescop Olivier , Roussarie Vincent
Published: May 2008

The aim of the study was to determine the hand-arm equal sensation curves for steering wheel translational and axial vibration. A sensory panel of 10 trained judges performed a two-step procedure. The test stimuli used were sinusoidal vibrations in the range from 4 to 60 Hz, with amplitude of 0.2 m/s2 rms. The first step was to determine perceived sensations for each frequency. Four families of vibration were defined (pumping movement, shaking sensation, trembling sensation and prickling sensation). The second step was a three-down-one-up test based on these families to determine the equal sensation level. Results showed that perceived intensity depends on vibration family, frequency and excitation direction (translational or axial).
Adaptation of the propagator for numerical acoustic holography of a wheel type object
Authors: Le Bourdon Thibault , Martin Vincent
Published: May 2008

Holography procedure of a vibrating object can be geometrically interpreted resulting in a guarantee of its identified vibratory velocity, the quality of which depends on the pressure measurement at an array of microphones and on the propagation model. In case of a wheel with the panel body, a plane array parallel to the visible side is the only one possible. The velocity is then accessible on the side concerned and needs a propagation model with adequate acoustic conditions over the whole plane with the visible side (source plane). Having in mind such a configuration, a theoretical work in the 3D space has shown the surrounding influence on the reconstructed velocity on the visible side. It has appeared that vibrations other than the ones of the front side and the rear acoustic load can be described with an admittance on the source plane. We present here an exhaustive search for the adequate admittance concerned leading to a correct propagator and a correct velocity identified. The success achieved in the procedure may rely on the single velocity and single model liable to radiate a given pressure on a sufficiently large antenna.
A first step toward a close proximity noise map
Authors: Bueno Moises , Viñuela Urbano , Terán Fernando , Paje S. E. , Luong Jeane
Published: May 2008

In recent years, environmental noise has become a serious issue for civil infrastructure and environmental administration due to public concern over the subject of noise pollution. The most significant deterioration of environmental acoustics conditions comes from road traffic transportation. The predominant noise source is the combination of the tire/pavement interaction and the propulsion systems of the vehicles. Generally, tire/pavement interaction is the principal source of noise for speeds above 40 km/h in the case of most modern cars. In this research, geo-referenced close proximity rolling noise is used for acoustical characterization of asphalt concrete surfaces in an urban environment. A close proximity noise map of streets with low speed limits is presented for a reference speed of 50 km/h. Different pavements and pavement conditions, common in urban streets, are analyzed: dense and semidense asphalt concrete, with Spanish denomination D-8 and S-12, respectively, and on the other hand, dense pavement at the end of its service life (D-8*). Noise levels from dense surfaces (D-8) increase significantly over time, principally due to the appearance of surface defects such as cracks and ruts.
A noise classification system for low-noise road surfacings - experiences and status
Authors: Andersen Bent , Kragh Jo/rgen , Thomsen Sigurd N.
Published: May 2008

As a result of an increasing pressure from the population as well as from road administrations a noise classification system for road surfacings was put into operation in the autumn 2006. The so-called SRS-system (a Danish abbreviation for noise reducing wearing courses) is provisional and non-committal for a couple of years until sufficient experience has been collected. It is a comprehensive system including: ̇Guidelines on the use of low-noise asphalt surfacings for noise abatement. ̇Method for declaration and documentation of noise reduction based on the CPX (close proximity)-method. ̇Paradigm for use in preparation of tendering documents and contracts. The measurement method is based upon the ISO draft standard describing the CPX-method, but includes further specification. Reference values for dense asphalt concrete are defined, and 2 dB wide noise reduction classes A, B, and C are defined at 50 and 80 km/h. The method also specifies an inter-calibration procedure (including definition of reference road sections) to be applied for different CPX measurement devices. Each year a specific calibration constant is issued for each device. The paper will also discuss the recent developments in the selection of future reference tyres for CPX measurements. Finally, a status of the classified surfacings will be presented.
Naïve and expert listeners use different strategies to categorize everyday sounds
Authors: Lemaitre Guillaume , Houix Olivier , Misdariis Nicolas , Susini Patrick
Published: May 2008

We report an experiment investigating the influence of the expertise of listeners on the strategy used to categorize sounds. A set of sixty kitchen sounds was selected, based on their causal uncertainty (ranging from very well identified to ambiguous). Thirty listeners were selected on the basis of their expertise in sound and music: fifteen "experts" and fifteen "naïves". First, they had to group together the sounds. Second, they had to describe the properties shared by the sounds in each category. Finally, they were provided with a description of different strategies of classification previously identified (acoustical, causal or semantic similarity), and required to indicate, for each category, which one they had used. The results show a strong influence of the expertise of the participants: while naive listeners made categories mainly on the basis of the events that they identified as having caused the sounds, experts made mainly categories of sounds on the basis of the perceived acoustical properties (timbre, time patterns, etc.). This result is coherent with the available literature demonstrating the coexistence of different strategies of listening, and links these strategies to the skills of the listeners. [This work is founded by the FP6 NEST Pathfinder European project CLOSED]
When exposed to sounds, would perceived loudness not be affected by social context
Authors: Stallen Pieter Jan
Published: May 2008

After decades of predominantly correlation studies of non-auditory factors and environmental noise annoyance, Maris, Stallen, Vermunt and Steensma (2007a,2007b) have demonstrated experimentally that a negative and positive relationship between producer and receiver of environmental sounds can cause the receiver to be more and less annoyed by the sound, respectively. This finding raises the question whether the context of environmental sound, and social context in particular, could already be determining responses to environmental sounds at earlier stages of auditory processing. This paper will present answers regarding perceived loudness, which is generally considered to be a more immediate (and less evaluative) response to sound exposure than the feeling of annoyance. From a statistics point of view, there is room for early influences as isophones which are based upon equal loudness judgments seem to hide no less, if not more, variation than the mean annoyance score at various sound pressure levels (cf. Berglund and Preis, 1997). It will be argued that seemingly conflicting empirical findings could be reconciled by postulating different attentional mechanisms as they vary with task characteristics and demands. Ideas will be presented by which the presumed theoretical model could be tested experimentally.
Comparison of Japanese and English language descriptions of piano performances captured using popular multichannel microphone arrays
Authors: Martens William L. , Kim Sungyoung , Marui Atsushi
Published: May 2008

In a cross-cultural comparison of musical sound evaluations, the way in which bipolar adjective pairs are used by native speakers of Japanese and English language was studied via a subjective rating task. These ratings were collected in response to eight solo piano performances that had been captured using four popular multichannel microphone arrays, reproduced via a standard 5-channel loudspeaker array, re-recorded binaurally, and finally presented via headphones. This allowed nearly identical stimuli to be presented to all listeners, without any modulation of the loudspeaker signals via listener head movements. Average ratings were compared to acoustical measures made on the 32 binaural stimuli, and to salient perceptual dimensions that previously had been derived from pairwise dissimilarity ratings between the stimuli. Results showed close agreement in how the selected terms were used by native speakers of Japanese and English language in the context of this study.
Parametric audible sounds by phase-cancellation excitation of primary waves
Authors: Kamakura Tomoo , Sakai Shinichi , Nomura Hideyuki , Akiyama Masahiko
Published: May 2008

An ultrasound source with a simple configuration is considered as a theoretical model. The source with a circular aperture consists of two coaxially arranged planar emitters: i.e., one is an inner disc emitter and the other is an outer ring emitter. The active areas of these emitters are the same. The outer diameter of the source is 20 cm. Both the emitters are driven individually at the same frequencies of 40 and 42 kHz but different phase angles. Especially, we focus on two extreme cases of the usual in-phase driving and out-of-phase driving. Numerical computation using the KZK equation demonstrates that when the driving signals are in phase the difference frequency beam of a 2-kHz wave has a candle-flame-like directivity. The beam has a similar directivity when the signals are out-of-phase by 180 degrees, although the peak of the sound pressure level decreases by few decibels. Interestingly, the second harmonic pressure level of the difference frequency reduces by ten decibels and more. Needless to say, the pressure amplitudes of the primary waves are suppressed considerably near the beam axis. Experimental verification is done using an airborne ultrasound source with a 19.2-cm circular aperture.
The Generation of Acoustic Waves and Cavitation Processes in Regime of Phase Synchronization During Multichannel Discharges in Electrolyte
Authors: Teslenko Vyacheslav S. , Drozhzhin Alexey P. , Medvedev Ruslan N.
Published: May 2008

In the paper the problems of acoustic waves generation of required frequency, amplitude and profile by the phase synchronization of multichannel discharges are considered. The phase synchronization of discharges is supplied by the implementation in the discharge circuit of additional inductance which acts as a dynamic feedback and ensures the selfsynchronization of N generated bubbles and acoustic wave's radiation [1]. The devices of such types may be used to form acoustic fields with required frequency and shape. References: 1. V. S. Teslenko, R. N. Medvedev, and A. P. Drozhzhin, Self-Synchronization of Electrohydrodynamic Autooscillations during Multichannel Discharges in Electrolyte // ISSN 1063-7850, Technical Physics Letters, 2007, Vol. 33, No. 10, pp. 833-836. http://www.swsl.newmail.ru/publ/TEPL833.pdf
Inverse Problem to Determine an Epoxy Film Parameters in a Tri-Layer Metal/Adhesive/Metal Structure
Authors: Ismaili Alaoui Naima , Ech-Cherif El-Kettani Mounsif , Chenouni Driss , Lakhlii Zakia , Izbicki Jean-Louis , Morvan Bruno
Published: May 2008

The aim of this work is to give the elastic parameters and the thickness of a slim epoxy film of a tri-layer metal/adhesive/metal structure, by inverse problem on the experimental data, knowing the characteristic equation of the structure. This equation is firstly solved and the sensitivity of some modes to the parameters of interest is studied. The couple of solutions wavenumber-frequency obtained from the direct problem are reintroduced in the characteristic equation, looking for the longitudinal and shear waves velocities, and the epoxy thickness that minimise this equation. A criterion that takes into account the averaged and the variance values of each parameter is deduced and allows these parameters determination in ±3% of the used values. To test the reliability of the method, the wavenumber solution is randomly perturbed in ±5% range, as the experimental wavenumber is expected to be weakly different from the theoretical one. The velocities and the thickness obtained still in the ±3% range around the used values. This method is then applied on experimental data obtained from a Duraluminum/epoxy/Duraluminum structure. The longitudinal and shear velocities and the thickness of the epoxy film obtained are in ±3% around the given values.
Nondestructive Evaluation of heterogeneous materials using acoustic emission and ultrasound
Authors: Faiz Adil , El Guerjouma Rachid , Bentahar Mouras
Published: May 2008

Heterogeneous materials as Composites and concrete are advantageous as structural components in many applications. However, damage detection in such materials is difficult due to their heterogeneity and anisotropy. Furthermore, conventional non destructive technique as X-radiographic is mostly not very sensitive to early damage and very time consuming and expensive. The purpose of this contribution is to study the capabilities of several methods, non destructive and very sensitive for damage characterisation, as Acoustic Emission (AE) and ultrasonic for the structural health monitoring of heterogeneous materials as polymer based composite materials and concrete. These materials are instrumented by piezoelectric sensors in order to detect acoustic emission and to measure the ultrasonic velocity. The mechanisms of the damage events and their space-time localizations are identified from AE. Simultaneously, the longitudinal ultrasonic velocity is measured in situ by transmission through the composites thickness. The AE is very well correlated with the loss of stiffness determined from ultrasonic velocity measurements showing the potentiality of this combined approach for in situ structural health monitoring.
The role of coherent phonons in the vibronic laser
Authors: Gadomski Wojciech , Gadomska Bożena
Published: May 2008

Herewith we present the quantum theory of the vibronic laser, which is based on the crucial role played by the host crystal phonons in the laser dynamics. In the solid state transition-metal ion laser the operation takes place between the vibronically broadened electronic levels of the gain center, thus the laser action is accompanied by the creation or annihilation of the host lattice phonons. The nonequilibrium coherent phonons, produced in the process of the nonradiative energy transition from the photoexcited impurity ion, pump the energy level, from whivh the laser action takes place. One can say that the laser photons are produced at the cost of lattice phonons. This is the reason why the coherent phonons strongly influence the character of the laser action and govern the complicated laser dynamics. In the laser equations, derived by us, the number of coherent phonons is treated as one of dynamical variables coupled with the number of photons. In solution we observe the effect of energy pulling between photons and phonons. Phonons follow all forms of the photon dynamics including self-pulsations and chaotic dynamics.
Picosecond ultrasonics signal in biological materials: Comparison between predictions and experiments
Authors: Ducousso Mathieu , Rossignol Clément , Audoin Bertrand , Guillemot Fabien , Durrieu Marie-Christine
Published: May 2008

Picosecond ultrasonics is a non-destructive method for measuring mechanical properties such as velocity or stiffness coefficients for nanometric materials [1]. This technique uses femtosecond laser pulses for generating and detecting acoustics waves from GHz to THz. Its resolution is about nanometers in depth and a few micrometers laterally. For transparent materials it allows generating the so-called Brillouin oscillations, which frequencies are determined by the material sound velocity and the light beam wavelength. In this paper this technique is applied to biological cells. Measurements suggest promising perspectives for the imaging inside a single living cell; frequency content is from 5 to 20 GHz. A theoretical model based on Fourier heat and acoustic wave equations has been developed. These equations include heat diffusion and acoustic propagation respectively. It permits numerical simulations in time domain. First experimental results on animal and vegetal cells are presented and confronted with these calculated waveforms. [1] C. Thomsen, H. T. Grahn, H. J. Maris, J. Tauc, Phys. Rev. B 34, 4129, 1986
Role of temporal fine structure in speech perception
Authors: Zeng Fan-Gang
Published: May 2008

Recent studies have shown that lack of access to the temporal fine structure cue is a major reason for the difficulty in speech perception in noise by hearing-impaired listeners. To further understand the role of temporal fine structure, we need to define the temporal fine structure and to delineate its relationship to the temporal envelope in both acoustical and perceptual domains. This talk will first examine the relationship between temporal envelope and temporal fine structure in signal processing terms and then relate it to speech production and perception. Acoustically, the temporal fine structure primarily contributes to changes in fundamental frequency, harmonics, and formant transition. Perceptually, while the temporal fine structure can contribute to speech intelligibility via the formant transition cue, it contributes to speech perception in noise by enhancing auditory objection formation rather than increasing speech intelligibility directly.
Relative importance of E and TFS speech cues in low and high-frequency channels
Authors: Ardoint Marine , Lorenzi Christian
Published: May 2008

Previous studies have shown that perfect speech identification in quiet could be obtained for broadband speech processed using the Hilbert transform to preserve either temporal envelope (E) or temporal fine structure (TFS) cues only in narrow frequency bands. However, little is known regarding the respective contribution of each cue to speech intelligibility in low and high frequency bands. The goal of the present study was to assess the contribution of E and TFS cues of the low- and high-frequency channels to consonant identification. Vowel-consonant-vowel stimuli were split into an array of 16 analysis bands spanning the range 80-8,020 Hz and processed using the Hilbert transform to keep either E or TFS cues only within each band. Identification scores were measured for low-pass and high-pass filtering of the processed stimuli for a group of normal-hearing listeners. Results will be discussed in light of phase-locking properties to E and TFS. In most mammals, phase-locking of auditory-nerve fibers begins to decline above 1 kHz and disappears above 4-5 kHz. TFS-coded speech intelligibility should therefore drop when stimuli are high-pass filtered above 1 kHz and be at chance level for high-pass filtering above 5 kHz. No such drop should be expected for E-coded speech.
The importance of temporal fine structure coding for speech perception in listeners with sensorineural hearing impairment as compared to normal hearing listeners
Authors: Buss Emily , Hall Joseph W. , Grose John H.
Published: May 2008

Physiological data suggest that the neural representation of temporal fine structure could benefit speech recognition in normal hearing listeners. Conversely, it has been hypothesized that deficits in the encoding of fine structure could play a role in the poor speech perception of patients with sensorineural hearing loss, particularly for speech presented at moderate to high levels and speech presented in background noise. Experiments on the psychoacoustical abilities of adults with hearing loss have shown a correlation between performance on tasks thought to rely on fine structure cues (e.g., low rate FM detection) and ability to understand speech or lowpass filtered speech, lending support to this hypothesis. This talk will review these data, as well as the mechanisms proposed to account for this result, and will consider the relation of these findings to experiments with normal-hearing listeners.
Evidence of neural processing of the interaural correlation between long-duration noises in humans
Authors: Wang Wenjie J. , Kong Lingzhi Z. , Li Jingyu Y. , Huang Qiang , Wu Xihong H. , Li Liang
Published: May 2008

When the delay between two correlated sounds is sufficiently short, attributes of the lagging sound are perceptually captured by the leading sound, causing a fused image as coming from the leading-sound location. To investigate neural processing of the interaural correlation between long-duration sounds in humans, we recorded scalp event-related potentials (ERPs) to a transient silent gap that was inserted in long-duration broadband noises presented via headphones. The noises at the two ears were either correlated or uncorrelated. When the noises were correlated but not uncorrelated, participants mainly perceived only one gap image whose inside-head position was modulated by the interaural time difference (ITD). Compared to ERPs when the noises were uncorrelated, the amplitude of the N1/P2 component to the gap was smaller and amplitudes in the latency range of 100 to 200 ms were more imbalanced between the two hemispheres when the noises were correlated. When the ITD for the correlated noises was increased to 16 ms, which was beyond the ITD range for fusion, two gap images were perceived, and the amplitude of the N1/P2 component to the gap became larger and the sustained potentials during 300-500 ms after the gap onset became more negative. [Supported by NSFC].
The effect of regional dialect on the psychometric reliability and validity of two sets of Mandarin speech audiometry materials
Authors: Nissen Shawn L. , Harris Richard W. , Garlick Jamie , Richardson Nathan
Published: May 2008

Previous research has shown conflicting evidence on the effect of testing an individual's hearing acuity with speech perception materials created in a mutually intelligible, yet non-regional dialect. Thus, the aim of this study is to examine the validity and reliability of using previously developed psychometrically equivalent speech audiometry materials in Mainland Mandarin and Taiwan Mandarin to evaluate the speech perception abilities (word recognition and speech reception threshold) of regional and non-regional listeners of the presented dialects. In addition, this study will investigate whether a native speaker of one Mandarin dialect is able to accurately administer and score the results from listeners of a different regional dialect. Some aspects of the listeners' performance on materials from a non-regional Mandarin dialect were found to be significantly different statistically. However, it is unclear if such differences are large enough to make a difference in the clinical testing of speech perception. In terms of scoring accuracy, a high percentage of agreement was found between the two interpreters from different dialectal backgrounds. [Work supported by research funding from Brigham Young University School of Education]
Performance on auditory temporal-processing tasks for speech and non-speech stimuli by young and elderly listeners
Authors: Kewley-Port Diane , Humes Larry , Fogerty Daniel , Kinney Dana
Published: May 2008

Results from three auditory tasks are presented from a larger series of temporal-processing tasks completed in three sensory modalities by young and older adults. The first task measured temporal gap detection in noise bands. The second and third tasks used digitally processed vowels in four words (pit, pet, pot, put) as the stimuli. The second task required listeners to identify the order of either two- or four-vowel sequences presented monaurally or dichotically. The third task measured the identification of these four vowels when presented either before or after a noise or vowel-like masker (forward- or backward-masking tasks). Altogether, performance was obtained for 14 auditory temporal-processing measures. Young (N=20) and older (N=50) adults participated. Preliminary analyses (based on data from 50 of the 70 subjects) indicate that young listeners performed significantly better and with less variability than elderly listeners on all tasks. For most tasks, there was considerable overlap between the data from young and elderly listeners, indicating a modest negative impact of aging. At the individual level, correlational analyses among the older adults indicated that pure-tone thresholds were not predictive of temporal-processing performance and that performance on many of the temporal-processing tasks was moderately correlated. [Supported by NIA R01 AG022334.]