bluuebunny/crossref_metadata_2025 huggingface dataset:
Affective judgment of aircraft sound quality
Authors: Västfjäll Daniel , Ingvarsson Àrni , Kleiner Mendel
Published: July 2002

Emotion is an important feature of the description and evaluation of sound quality, but this fact has often been treated as a ‘‘nuisance variable’’ in sound quality. The objective of this study was to investigate sound quality descriptors of aircraft sounds. The approach to descriptors in this case originated from the need for consideration of emotion in sound quality research. Thirty-two participants (n=32) rated eight recorded sounds from turboprop aircraft binaurally replayed over headphones. Subjects rated 21 descriptors designed to capture the subjective dimensions of aircraft sounds. The descriptors were commonly used sound quality adjectives, which have emotional/affective connotation. The principal component analysis resulted in two main components. The first factor was interpreted as pleasantness and the second factor as stimuli intensity. These results indicate that affective descriptors can model perception of aircraft sound, i.e., emotional evaluation is important to aircraft sound quality. This study indicates that both description and judgment/decisions about sounds can be based on emotions. One approach to understand and improve sound quality modeling is to investigate the subjective emotional impression of sounds. [Work supported by NFFP Grant No. 232.]
Local ordinance targeted to low-frequency noise
Authors: Brooks Bennett
Published: July 2002

The local authorities of a suburban town wanted to control the low-frequency noise emissions due to the musical entertainment at night clubs and taverns. Complaints from residents about booming bass guitar and drum sounds had to be balanced with the need for tavern owners to conduct business reasonably. It was recognized that the existing town code, which placed limits on A-weighted noise levels at property boundaries, was not an effective means to control low-frequency noise emissions. A revised ordinance was developed to address this issue, which now places additional limits on the allowable noise levels in specific octave bands. In particular, this includes the low-frequency (bass) octave bands. The octave band limits were selected such that the summation of band levels equals the A-weighted overall noise limit.
A new hybrid approach, for estimating in situ the acoustic power radiated from vibrating structures
Authors: Nicolas J. , Beslin O. , Foin O.
Published: July 2002

Measuring in situ, the acoustic power radiated by a vibrating panel with classical intensity techniques, is not always possible because of the influence of other surrounding sources. This is a major difficulty during the characterization in vehicles’ noise problems. In this paper, a new experimental–numerical hybrid approach is presented which permits the evaluation in situ, of minimum and maximum indicators for the acoustic power intrinsically radiated by a particular panel situated in a more complex system. This is a two-step method: (i) the in situ vibration field of the panel is measured using a laser scan or an accelerometers array. (ii) Two indicators of the acoustic power are calculated. A minimum indicator is obtained by calculating the acoustic power radiated by the panel vibration field as if it were in free space (unbaffled vibration field). A maximum indicator is calculated considering a baffled vibration field (half free space). Interestingly enough, the measured data are projected in a base of trigonometric functions which allow quick calculations for a large frequency span. Then, precomputed baffled and unbaffled radiation impedances are used to calculate the radiated power. Comparisons between exact and estimated radiated powers are presented and discussed.
Localization of noise sources inside machines by using a scaled dummy head
Authors: Illaire Helene , Blomqvist Jens
Published: July 2002

This study presents the use of the fine spatial resolution of the human auditory system to localize sound sources in small enclosures, by means of a 1:10 scale dummy-head and subsequent real-time frequency scaling. This method has been applied to the localization of rattle sources in the gearbox of a truck. After investigation of cues necessary for localization in the horizontal plane in a reverberant environment, a dummy-head of a scale of 1:10 has been designed. The dummy-head reproduces the general shape of the human head but the pinnae are not found necessary for inclusion for this investigation at low frequencies. To preserve the ability to localize, the frequency content of the recorded signal is scaled by the same factor as the dummy-head, i.e., it is divided by a factor of 10. Therefore, a frequency divider system has been developed to divide the frequency in real-time by 10 and uses a time-expansion method. The design of the system and the problems encountered are presented, together with the results obtained.
Development of a high-frequency precision anechoic test facility
Authors: Duda John , Hirschorn Martin , Gilbert Mark , Torio Guy
Published: July 2002

Although anechoic wedges with absorption coefficients of 0.99 as tested in typical impedance tubes meet ISO inverse square-law standards, they may not be satisfactory for anechoic rooms used for measurements of microphone response characteristics. Due to size restrictions, impedance tube tests are limited to frequencies below about 250 Hz and there is no standard method to test wedges for absorption at higher frequencies. This paper describes how pulse signal and reverberation room tests were employed to rank the high-frequency performance of three types of anechoic wedges considered for a microphone test facility: Standard patented MetadyneTM (perforated metal) wedges—conventional fiberglass wedges and an improved high performance Metadyne wedge system. The results of laboratory tests and tests conducted in anechoic rooms are presented. In all cases the preferred system, high-performance Metadyne wedges, is shown to meet the stringent acoustic absorption requirements needed for this application. The paper indicates the need for new standards for laboratory testing of anechoic wedges at high frequencies and an alternate method to inverse square-law tests for evaluating anechoic room performance such as stepped frequency sweep tests. Such a new standard will be proposed in the presentation.
A surface element formulation of the equivalent source method
Authors: Svensson U. Peter , Nakano Mayumi , Sakagami Kimihiro , Morimoto Masayuki
Published: July 2002

A time-domain formulation of the equivalent source method which uses planar surface elements is presented. The boundary condition of a closed surface can be fulfilled using monopole elements for boundary conditions specifying the normal velocity, the sound pressure, or the local impedance. By interpreting the equivalent sources as double layers of free-field radiating monopoles with a uniform source signal over the element, the impulse response matrix is easy to find via the Rayleigh integral. The problem of determining the source signals of these equivalent sources involves the inversion of a single real-valued matrix as shown in Kropp and Svensson [Acustica 81, 528–543 (1995)], and the matrix is very sparse. The relation to the boundary element method is discussed, and as an example, the sound radiation from a kettledrum is presented. By using a Green’s function technique, any vibration pattern can be synthesized using post-processing. Interpolation can be used to study the far-field radiation of vibration patterns that are more complicated than the element mesh can resolve.
A combined finite-element, boundary integral, and spherical harmonic hybrid technique for computing multiple-body sound radiation
Authors: Blottman John B. , Kalinowski Anthony J.
Published: July 2002

Transducer interactions within an array are known to affect the array performance and the life expectancy of the transducers. The ability to predict array performance is required for large close-packed arrays of acoustic transducers. In these cases, traditional full finite-element methods prove costly. A combined multiple acoustic scattering model that is based on spherical harmonic functions and a finite-element-based description of an elastic body of arbitrary geometry is formulated to predict the performance of an array of acoustic transducers. The finite-element model produces the dynamic system matrix. A boundary integral equation relates surface pressure and velocity. Boundary elements are partitioned for the case of the surface of an arbitrary body circumscribed by a spherical surface to provide an implicit transfer of surface pressures to spherical fluid pressures and particle velocities. These quantities are then transformed in terms of spherical harmonics. The resulting series is combined with the spherical harmonic representation of the fluid using the addition theorem for multiple scatters. The technique has been exercised to evaluate an array of piezoelastic shells, driven by an electrical potential. Results compare well to those of a coupled finite-element–boundary-element method. [Work sponsored by the Office of Naval Research.]
How reliable is the method of comparative sources?
Authors: Machens Kai-Ulrich
Published: July 2002

Radiation and scattering from vibrating bodies can be expressed by a source system that is placed inside the radiator and whose source strengths are determined appropriately. The method of comparative sources (MCS) provides an estimate of these source strengths from the near-field data. The MCS is reviewed by applying it to cylinders with elliptical cross section. This geometry is suitable to check the method for two reasons. First, it is general enough to demonstrate methodical difficulties which arise from its spatially varying field impedances as a result of different surface curvatures. On the other hand, it is not too complicated to allow analytical treatment by Mathieu functions. Therefore, it is possible to generate exact solutions of the sound field from different, more and less efficiently radiating velocity distributions. These solutions are compared to results obtained by the MCS, in which various source systems and different weighting functions are used. This way, it is demonstrated that the relative error in the surface velocity approximation generally is not proportional to the error in the radiated sound power. Moreover, it is shown that certain weighting functions may be advantageous and that it is more difficult to predict inefficient than efficient radiators by this method. a)Now at Daimler-Benz Group, ATG Research and Technology.
Ultrasound cleaning of microfilters
Authors: Hald Jens , Bjo/rno/ Irina , Bjo/rno/ Leif
Published: July 2002

The aim of the present work is to develop, design, and manufacture a high-power ultrasound transducer module to be used for preventing the blocking of plastic-based microfilters by organic materials, and possibly to prolong the lifetime of the filters in industry using the cavitation on the surface of the filter. A numerical, FE- and BE-based model for calculation of the response of ultrasonic transducers of various geometries formed the basis for the design of such transducers. During laboratory experiments frequency and output power have been varied in order to find the optimal transducer design suitable for cleaning of microfilters without damaging the filter structure. The filter surface was studied using an optical microscope before and after the experiment. When high-power ultrasound (max. 75 W/cm2) was applied to the surface of some microfilters, no visible damage was found, while others filters were damaged. The results of the laboratory experiments formed background for the final design of an ultrasound transducer module for use by foodstuff filtration plants. [This work was financed by the EU Project WAMBIO PL96-3257 (FAIR Programme).]
Acoustoelectric effect in gas sensor of the SAW type
Authors: Urbanczyk Marian , Opilski Aleksander
Published: July 2002

The initial value of the electric conductivity of the sensorial layer determines the working point of the sensor and is of essential importance with respect to the sensitivity of the sensor, because it determines the value of the acoustoelectric effect in that system. Basing on measurements it has been found that the electric conductivity of a lead phthalocyanine layer placed in an NO2 atmosphere increases. This effect becomes higher as the temperature rises. In a SAW sensor the effect of the electric potential of a surface wave with a sensorial layer occurs in a high-frequency field. It has been found that the conductivity of lead phthalocyanine layers depends on the frequency to an extremely high degree. If compared with direct-current measurements, the alternating-current conductivity is greater by about two orders; its frequency being equal to the frequency of the propagated surface wave applied (43 MHz). Practically, the value of the conductivity of semiconducting layers at higher frequencies makes possible the occurrence of an acoustoelectric effect in the sensor.
Effects of grain size and shape on ultrasonic attenuation and backscattering
Authors: Thompson R. B.
Published: July 2002

The influence of scattering from gain boundaries on the attenuation and backscattering of ultrasonic waves in polycrystals is a classical problem which has received considerable attention. However, the great majority of the effort has considered equiaxed grains. Extensions to polycrystals with elongated grains and multiple dimension scales will be presented. Experimental results will be reported for aluminum and titanium polycrystals, including a number of cases in which the directions of high attenuation exhibit low backscattering and vice versa. Although these observations were initially found to be surprising, significant progress has been made towards an understanding. The status of diagnostic experiments and theoretical efforts to explain these observations will be summarized. Implications of the results in the design of improved nondestructive techniques to detect flaws and characterize microstructure, including progress towards in situ techniques to monitor recrystallization will be discussed. [Portions of this work supported by the United States DOE, NSF, and the FAA.]
Ultrasonic anomalies in betaine phosphate/betaine phosphite mixed crystals
Authors: Banys Juras , Samulionis Vytautas , Voelkel Georg , Kloepperpieper A.
Published: July 2002

Measurements of the longitudinal ultrasonic velocity and the attenuation along the x, y, and z axes have been carried out in deuterated betaine phosphite (DBPI) single crystals in the vicinity of the ferroelectric and antiferrodistortive phase transitions. For ultrasonic modes propagating along the x and z axes the critical slowing down has been observed, but along the y axis critical slowing down was absent for both phase transitions. Regardless of the weakness of elastic anomalies at ferroelectric phase transition the ultrasonic behavior in DBPI can be explained by the Landau–Khalatnikov theory for uniaxial ferroelectrics. The ultrasonic behavior at the antiferrodistortive phase transition indicates that this phase transition is very close to the tricritical one. The relaxation time of the order parameter in the vicinity of the transition to the antiferodistortive phase for DBPI crystal was estimated. Similar results have been obtained for the mixed crystals betaine phosphate/betaine phosphite in the region of the antiferrodistortive phase transition. The temperature behavior of the ultrasound velocity and attenuation indicates the existence of the ionic conductivity in these cystals. It should be noted that conductivity phenomena is highly anisotropic in these crystals.
Picosecond ultrasonics in gold nanoparticles
Authors: Devos Arnaud , Perrin Bernard , Jeannet Jean Claude
Published: July 2002

Pump–probe optical techniques with femtosecond laser sources can be used to provide information about the acoustical properties of very thin films. With this so-called ‘‘picosecond ultrasonics technique,’’ echoes shorter than 10 ps can be time-resolved in films whose thicknesses are larger than a few tens of nm; for smaller thicknesses, the acoustic excitation induces very high frequency acoustic resonances ranging from 0.1 up to 2.5 THz. In this work, the results of a picosecond ultrasonics experiment performed on gold colloids which represent an example of nanostructures is presented. The samples studied were of three types: solutions (gold particles dispersed in water), gels (gold particles embedded in a polymer matrix), and a film of particles attached on a polymer monolayer. The particle size was between 5 and 20 nanometers. In all the samples, oscillations in the transmitted probe beam which are ascribed to the vibrational mode of the sphere were observed. A second oscillation with a much longer period is also reported in the solution and gels cases. [Work supported by CNRS.]
Efficiency of a medical treatment of the acoustic trauma following impulse noise exposure in the guinea pig
Authors: Magnan Pascal , d’Aldin Christine , Dancer Armand L.
Published: July 2002

Most of the patients suffering from acute acoustic trauma have been exposed to impulse noises. Temporary or permanent threshold shift (TTS or PTS) can be observed after such an exposure. They are correlated to structural and functional modifications of the peripheral auditory system and particularly of the sensory hair cells. Studies performed in guinea pig exposed to continuous noise have shown a positive effect of corticotherapy and oxygenotherapy (the treatments are given immediately after the end of the exposure). The aim of this paper is to assess the efficiency of those treatments in the guinea pig exposed to impulse noises; i.e., 20 pistol rounds of 157-dB peak pressure (at a 5-s interval). Threshold shifts (electrocochleography) and distortion products are measured for 15 days and are compared with histological observations (scanning electron microscopy). The results allow one to understand better the cochlear mechanisms of damages and to assess the efficiency of the classical treatments of the acoustic trauma following impulse noise exposures.
Modeling of borehole Stoneley waves in the presence of skin effects
Authors: Tichelaar Bart W. , Liu Hsui-Lin , Johnson David L.
Published: July 2002

An important aspect of oil production from a geological formation is the process of flow into a well penetrating the formation. Recent laboratory experiments indicate that well-inflow can be significantly reduced by a skin effect caused by the presence of a thin layer of low permeability around the wellbore. This impairment layer is drilling induced and differs from the mudcake that is usually encountered when logging a well. Whereas a mudcake may have built up on the borehole wall during drilling, the drawdown pressure often removes it when oil is produced from the well. In contrast with such a temporary mudcake, the impairment layer is believed to form a permanent flow impedance throughout the lifetime of a well unless extensive cleaning measures are taken. A simple poro-elastic model is constructed to investigate the propagation of Stoneley waves in a borehole with a thin impairment layer. If the impairment layer affects Stoneley wave propagation, it may be possible to acoustically detect this layer with sonic logging tools. Using realistic values for the impairment flow impedance, model calculations for a typical sandstone reservoir of 20% porosity indicate that the impairment layer changes the dispersion characteristics of borehole Stoneley waves. The magnitude of these changes increases with increasing mobility of the reservoir pore fluid.
Acoustic monitoring of the transport and temperature variability in the Strait of Gibraltar
Authors: Worcester Peter F. , Send Uwe , Cornuelle Bruce D. , Tiemann Christopher O.
Published: July 2002

Three acoustic transceivers transmitted across the Strait of Gibraltar during April–May 1996 to determine the feasibility of using acoustic methods to measure the transport and average temperature in the Strait. The first arrivals, from ray paths confined to the (lower layer) Mediterranean water, give sum travel times that are remarkably stable, with a slow peak-to-peak variation of only about 3 ms over a two-week period, corresponding to an integrated temperature change of about 70 m °C. The difference travel times from a path diagonal to the axis of the Strait show a peak-to-peak tidal variation of about ±5 ms, corresponding to integrated currents parallel to the acoustic path of about ±50 cm/s, which is consistent with estimates derived from a moored current meter array. One of the transceivers also had a two-element horizontal receiving array, to determine the feasibility of using arrival angle to measure the current perpendicular to the acoustic path. The measured phase differences are encouragingly similar to phase differences predicted using the current meter data. Later arrivals, from ray paths that sampled the (upper layer) Atlantic water, are much more complicated, in part due to the effects of the internal wave bores present in the Strait.
Calibration of contact transducers by means of thermoacoustic sensors
Authors: Glinka Michael
Published: July 2002

The utilization of the thermoacoustic effect for measuring the absolute value of acoustic power by means of thermoacoustic sensors is discussed. The sensor’s response to the incident acoustic power is measured as the temperature increase T. This temperature increase is computed by the differential equation describing the sensor, which contains only the sensor’s material constants: density ρ, specific heat capacity cw, and conductivity Λw, ∂T/∂t=(Λw/ρcw)∇2T+(1/ρcw)⋅W. It is shown how the distribution of heat sources W (caused by the absorbed ultrasonic field) can be optimized for the realization of thermoacoustic sensors adapted to experimental situations. A discussion of different types of sensors will show that the complex transfer functions are restricted by the material constants. It is shown how the solutions presented can be used to improve the dynamic performance. Experimental results obtained by the use of different sensors and contact transducers (calibrated by the reciprocity method) are compared with respective solutions of the parabolic heat flow equation.
Comments on “Broadband spectra of seismic survey air-gun emissions, with reference to dolphin auditory thresholds” [J. Acoust. Soc. Am. 103, 2177–2184 (1998)]
Authors: Ridgway S. H. , Carder D. A. , Kamolnick T. , Schlundt C. E. , Elsberry W. , Hastings M.
Published: July 2002

Responses of marine mammals to human-generated sound are of interest due to concern for protection of animals with sensitive hearing from acoustic harassment or injury. [J. Acoust. Soc. Am. 103, 2177–2184 (1998)] compare their limited observations of wild common dolphins (Delphinus delphis) near operating seismic vessels off Wales, with studies of trained bottlenose dolphins (Tursiops truncatus) in San Diego Bay [, Tech. Rpt. 1751, NCCOSC RDTE (1997)]. Because of the considerable difference between numerous seismic pulses and the single 1-s tones employed by , the comparison is not valid. Further, Goold and Fish do not accurately represent the bottlenose dolphin responses.
High-frequency acoustic scattering from medium variability
Authors: Oeschger John
Published: July 2002

Laboratory results of high-frequency acoustic scattering measurements from thermal and saline driven plumes are reported. These experiments used broadband signals in a multi-static configuration. Far-field weak scattering theory describes the acoustic scatter from the medium variability. Expressions relating the acoustic scatter to the scattering field are given in terms of deviations from ambient of temperature and salinity or alternatively, sound speed and density. The angular dependence of the coefficient for the salinity difference has a stronger angular dependence than does the coefficient for the temperature difference. By using the common Bragg wave number comparisons [J. Oeschger, Proc. of 16th ICA and 135th ASA 2, 1335–1336 (1998)], multi-static measurements can be used to determine the source of scattering, either salinity or thermal in nature, without resorting to a priori information. Each angular dependent source-term normalization factor is applied in turn to the data and the one that yields the best agreement predicts the scattering source correctly. Results are also presented for medium mixing where the relative density fluctuations dominate the scattering mechanism. Again the common Bragg wave number comparisons using the multi-static data are able to determine correctly the source of scattering as predicted by supporting environmental measurements.
Incorporating gestures into the musical control stream with the conductor’s jacket
Authors: Marrin Nakra Teresa
Published: July 2002

Much contemporary music is created in a studio, put to tape, and performed through speakers to a passive audience. In the process, some of the excitement and spontaneity of live performances is lost. There is arguably a growing problem that our contemporary musical forms have become so complicated that they cannot readily be performed in live concerts. One solution to this problem is to build real-time sensor-based systems for artists to interactively and spontaneously perform with. However, as has been shown by numerous others, these systems are either too simple in their functionality or require such constrained gestures that they force the performer to conform to unnatural or nonintuitive gestures. This paper presents an approach that adopts a unique synthesis-by-analysis method, whereby the signals created by numerous professional musicians are gathered under various rehearsal and performance conditions, studied, interpreted, and used to inform the choices in a real-time performance system. The final results, which will be presented in this paper, demonstrate a variety of attempts to generate more natural, expressive, and intuitive mappings between gesture and sound. We will discuss three different examples, including one taken from a conducting-style gestural metaphor, one from tai chi, and one fron dance.
Acoustic feature extraction for characterizing and classifying animal sounds
Authors: Fristrup Kurt
Published: July 2002

Standardized measures for animal sounds were investigated as the basis for characterizing and classifying animal sounds. These measures were computed from a noise-compensated spectrogram. The performance of this system was evaluated in terms of the stability of measurements under varying noise conditions, and the ability to correctly identify sounds to species or individual in a variety of trials. Results from analyses of bird and marine mammal sounds will be presented. General considerations regarding feature and classifier selection will be discussed.
Preliminary results on the acoustic characterization of the Northern Right whale
Authors: Desharnais Francine , Hazen Mark G.
Published: July 2002

The Northern Right whale (Eubalaena glacialis) is the most endangered large whale species. Collisions with ships is the cause of a large percentage of documented deaths. An experiment is planned for the summer of 1999 to record vocalizations of the Northern Right Whale. The recordings will be made in the Bay of Fundy (Southeast of Grand Manan Island) and Roseway Basin (South of Nova Scotia). These areas were chosen because of the large occurrence of whale sightings in the summer months. Preliminary analysis of acoustic signals from the Right Whale will be shown. The statistical analysis of these signals should eventually allow the development of processing algorithms to recognize whale calls. Identification of unique features in the whale calls may allow localization and tracking of the Northern Right whales with a field of sonobuoys.
Source level estimation of dolphin communication calls as a potential method for species identification
Authors: Kaschner Kristin , Goodson A. David , Connelly Paul R.
Published: July 2002

Research into the acoustic structure of communication calls of different odontocete species has attempted to identify distinctive features that might assist in discrimination of individuals, pods or species. Most studies have concentrated on frequency modulation characteristics, such as the general shape or contour of the call. Although the source level (SPL re: 1 μPa at 1 m) of echolocation signals has been studied and appears to reflect some body size dependency, signal intensities of ‘‘whistles’’ have not been investigated closely. In this study maximum source levels of communication calls were estimated in open sea conditions, using an acoustic multi-path ranging technique. Preliminary results suggest species-specific differences in maxium call intensities that may provide a useful additional cue to acoustically distinguish species in the wild. Data used for spectral and statistical analysis were recorded using a single hydrophone attached to a pelagic trawl fishing in continental shelf waters in the Bay of Biscay. Maximum SPLs of social calls were extracted and distances between hydrophone and vocalizing animals were obtained exploiting information inherent in recorded muli-path signals. Concurrent visual observation provided species identification. Source levels of calls were calculated based on a calibrated reference signal. Methodology and limitations of this technique are discussed.
Elastodynamic response of ordered materials
Authors: Kinra Vikram K.
Published: July 2002

The interaction of a normally incident plane longitudinal wave with an ordered or disordered single layer of spherical inclusions embedded in a polyester matrix was measured. Inclusions were arranged in a periodic (square or hexagonal) and random arrays with area fraction ranging from 0.07 to 0.65. Measurements were carried out at wavelengths that are large, equal, or small compared to the two characteristic lengths of the composites, namely, the particle radius and the interparticle distance. The transmission and reflection spectra for periodic layers are characterized by several resonances, the frequencies of which are close to the cut-off frequencies of the appropriate shear lattice modes. The excitation of resonances is accompanied by the propagation of mode-converted shear waves, which are propagated along certain symmetry directions within the plane of the particles. These waves were detected by the use of a shear wave transducer. At the first lattice resonance frequency, the reflection coefficient of a layer drops down to near-zero value. The vibrations of an individual particle have been measured by a laser interferometer. Finally, a simple model of the elastodynamic event was constructed. In spite of its simplicity, the model captures the essential features of the experimental data.
One approach to architectural acoustics in education
Authors: Jaffe J. Christopher
Published: July 2002

In the fall of 1997, Dean Alan Balfour of the School of Architecture at Rennselaer Polytechnic Institute asked me to introduce an undergraduate course entitled ‘‘Sonics in Architecture.’’ I had previously taught a number of two-credit survey courses at Julliard, RPI, and City College of New York. My limited exposure as an adjunct professor did not prepare me for the difficulty of developing and integrating a 14-credit certificate course in what was in reality a vertical studio (a studio with students from different classes and disciplines). This paper discusses the curriculum I developed, the strengths and weaknesses of my initial plan, examples of student work and my revised curriculum for next year. In addition I will share my concerns regarding the teaching methods currently prevalent in many schools of architecture today, and how building science professionals might assist in addressing these issues. a)Distinguished Visiting Professor at the Rensselaer Polytechnic Institute.
African influences on jazz: A lecture–demonstration
Authors: McDaniel Ted W.
Published: July 2002

This presentation focuses on selective aspects of sound patterns and performance traditions from sub-Saharan African societies that are retained in various ways in African–American jazz and performance styles. The talk will examine specific timbres and their related practices of repetition, collective improvisation, the acoustic phenomenon of pitch-bending, and texture. Recorded examples as well as live performances will highlight these elements and establish their relationships to the sub-Saharan African examples. A group of jazz musicians drawn from the OSU Jazz Division will perform specific items that further illustrate the concepts and practices outlined.
Reduction of time-domain aliasing in adaptive overlap-add algorithms
Authors: Rass Uwe , Steeger Gerhard H.
Published: July 2002

The adaptive overlap-add algorithm (OLA) is an attractive means for acoustical signal processing (e.g., filtering, compression), since it is computationally effective and provides magnitude and phase information. It performs well when the input data blocks, the DFT, and the filter impulse response are of suitably chosen lengths. If the filter frequency response is altered on-line by an adaptation rule formulated in the frequency-domain, the resulting impulse response will, in general, be too long. This results in serious distortions, due to time-domain aliasing during the inverse DFT. Limiting the filter length by a filter design procedure needs much computation time, which is inhibitive for many acoustical applications. Time-domain aliasing distortions are particularly disturbing when musical signals are processed, due to their nonharmonic nature. An algorithm is proposed which convolves the filter frequency response with a short window sequence, solely in the frequency domain. Thereby, the aliasing components can be reduced by a predictable amount. The computational burden is low (approximately 12% add-on to the basic OLA algorithm) and, in addition, can be traded with the attenuation of the aliasing components. Discrete prolate spheroidal sequences have proven to be the optimal window type for this purpose.
Modifications of a handheld vacuum cleaner for noise control
Authors: Lauchle Gerald C. , Brungart Timothy A.
Published: July 2002

Sound power measurements are described for a commercially manufactured, handheld vacuum cleaner. An objective assessment of the measured results is performed to identify the aeroacoustic sources of noise, suggested routes to noise control are then implemented, and a re-evaluation of the modified units is conducted and compared to the baseline results. The blade rate tone of the vacuum working fan is found to be the most annoying source, and it is reduced by up to 8 dB through a modification of the shroud that surrounds it. Unevenly spaced fan blades are also implemented as a noise control measure. This results in a comparable 8-dB reduction of the blade rate tone, but it introduces several new, side band tones to the sound power spectral data; the overall sound power increases slightly. Regardless, a subjective jury survey indicated that the modified unit having the unequally spaced fan blades is preferred 3:1 to the unit with the modified shroud only. [Work supported by Royal Appliance Manufacturing Co.]
Measurement of acoustic properties by the two-cavity method
Authors: Nice Minor
Published: July 2002

In this paper, results of the measurement of the infinite thickness properties (characteristic impedance, propagation constant) of acoustic materials by the two-cavity method will be presented. Results for some standard fiberglass materials will be shown along with comparison to some well-known correlations (Delaney and Bazley, Beranek). Results for materials other than fiberglass will also be presented. The impact of various measurement parameters (cavity spacing, averaging, impedance tube size, etc.) will be discussed relative to the measurement technique.
Holographic sound-field imaging as a diagnostic tool
Authors: Washburn Karl B. , Godfrey Richard D.
Published: July 2002

Approaching its third decade, sound-field imaging using near-field acoustical holography has matured as an analysis technique. It has been established as the tool of choice for source motion mapping in structural acoustics and for source identification in noise control. The strength of near-field holography lies in its complete description of the sound field, from source to far field. This opens a door to using sound-field imaging as an acoustical diagnostic tool. Several current trends in applying holography, including moving sources, reverberant spaces, and lower-cost systems, are surveyed. New diagnostic applications of sound-field reconstruction in audio-source imaging, transmission path analysis, and boundary material characterization are described.
New geometric sound absorbers
Authors: Warnaka Glenn E.
Published: July 2002

This paper presents new concepts for simplified geometric sound absorbers that have a number of advantages over previous geometric sound absorbers and conventional sound absorbing materials. The new absorbers can be made of nearly any substance. Hence, the material for the absorbers can be selected on the bases of material costs, construction costs, and environmental considerations. They may be painted and cleaned without affecting their sound absorbing qualities. They also can be made very rugged for use in highway noise barriers and other outdoor applications. With the new geometric sound absorbers, it is possible to design absorbers that fulfill nearly any frequency range required. An infinite variety of designs is possible. In addition, the amount of sound absorption can be changed even after the sound absorbers have been installed. This may be of interest in multi-purpose rooms where the sound absorption can be altered for different functional uses of the room. The geometric sound absorbers may also be formed into flat treatments. Since the frequency range is a matter of design, high acoustic absorption can be maintained to frequencies well below 100 Hz, depending on design requirements, in treatments that are 6–16 mm thick.
Numerical solution of a statistical version of the Burgers equation
Authors: Menounou Penelope
Published: July 2002

The Burgers equation (BE) is transformed into an unclosed set of linear equations that describe the evolution of the joint moments of the sound signal. The set of the equations is represented by a recursion equation termed Statistical Burgers Equation (SBE). Unlike for the BE, the time signal at the source is not required for the solution of the SBE and the power spectral density of the signal (or of a stochastic process) can be given instead [Menounou and Blackstock, J. Acoust. Soc. Am. 99, 2539(A) (1996)]. The SBE is solved numerically by appropriately selecting only a finite number of equations from the infinite set, provided that the joint moments of the signal (or the stochastic process) are known at the source. The properties of the joint moments are presented for two source conditions: (i) a sinusoidal signal; and (ii) a Gaussian stationary and ergodic stochastic process. The finite difference scheme employed for the prediction of the joint moments’ evolution is presented and stability criteria for the algorithm are derived. Finally, the sequence of computing the equations within the set is investigated and its effect on the stability of the numerical algorithm is demonstrated. [Work supported by the F. V. Hunt Postdoctoral Fellowship.]
Mode counts for rooms and waveguides
Authors: Morfey Christopher L. , Wright Matthew C. M. , Yoon Seong-Ho
Published: July 2002

The density of modes in a room (3-D) or waveguide cross-section (2-D) is known to be approximated at high frequencies by expressions involving room volume and surface area, or (in 2-D) the area and perimeter of the waveguide cross-section. Deviations of the actual mode count from the smoothed approximation are studied numerically and analytically for simple shapes: rectangular (2-D and 3-D) and annular (2-D). Periodic clustering of eigenvalues, associated with cyclic rays [R. Balian and C. Bloch, Ann. Phys. 69, 76–160 (1972)] is demonstrated at high frequencies. Expressions are given for estimating the standard deviation of 2-D and 3-D mode counts from their smoothed values, in a finite frequency band, when one dimension is much smaller than the others.
A Bilger journey
Authors: Hirsh Ira J.
Published: July 2002

Bob Bilger started (1954) his postdoctoral appointment at Central Institute with Ira Hirsh. The topic was recovery of auditory threshold for tones, following exposure to tones. They confirmed the results of Hirsh and Ward (1952) on recovery of click thresholds after similar exposures. The collaboration continued with papers on masking, remote masking, and additivity of different kinds of masking. The organization at Central Institute was such that he, like other research associates, learned about and participated in work in other laboratories. He particpated in physiological studies; he branched out to time and speech; and his statistical expertise was much sought in clinical research. His move to Pittsburgh allowed him to continue his disregard for disciplinary barriers and his readiness for clinically related matters. Just before leaving Pittsburgh for Illinois, he undertook to write, organize and edit the impressive, monumental, first serious study of the effect of a single-channel cochlear implant on adult human subjects [Bilger et al. (1977)]. The Illinois stretch demonstrates that (1) speech and psychoacoustics are not very far apart, and (2) very successful Chairs of Speech and Hearing Departments need not be clinicians.
Physiological mechanisms of frequency discrimination
Authors: Javel Eric
Published: July 2002

I recall a conversation with Bob Bilger that occurred around 1971, when I was a graduate student in Bioacoustics at Pitt. He said (translated into English from the original Bilgerian), ‘‘Did it ever occur to you that you can apply principles of signal detection theory in physiological studies? That way, you could examine neural and psychophysical performance using comparable measures and possibly shed light on underlying mechanisms.’’ This idea, which predated its implementation in auditory research by at least 10 years, was initially lost on me. Much later, I recognized the possibilities and performed some pertinent experiments with various colleagues. We utilized 2AFC adaptive tracking procedures to investigate performance limits of single cat auditory nerve fibers and neural populations on pure-tone frequency discrimination tasks. For single-fiber responses, we found that: (1) decision strategies based on detecting differences in spike counts fail to account for perceptual findings by wide margins; and (2) strategies based on detecting differences in phase-locked activity produce data that match perceptual findings well at low frequencies but rapidly degrade at frequencies >1500 Hz. Examining neural population performance using a stochastic excitation pattern model, we found that a strategy which simply estimates the spatial location of the response peak accounts well for perceptual performance at most frequencies. See, Bob? Your idea works, and I WAS paying attention.
Modeling closed-set phoneme and open-set word recognition by multi-channel cochlear implant users
Authors: Meyer Ted A. , Svirsky Mario A. , Frisch Stefan , Kaiser Adam R. , Pisoni David B. , Miyamoto Richard T.
Published: July 2002

There has been phenomenal growth in research on speech perception by cochlear implant (CI) users since the printing of the ‘‘Bilger Report’’ [Bilger et al., Ann. Otol. Rhinol. Laryngol. 86 (S38), 1–176 (1977)]. Undoubtedly, average speech perception performance with these devices has improved dramatically. However, despite advances in implant technology, CI users continue to demonstrate a wide range in the ability to perceive speech. Little progress has also been made in understanding how CI users actually perceive speech. Although many correlational analyses have been carried out, little research has focused on mechanisms of speech perception, and many clinical decisions are made on a trial-and-error basis. Using a new approach, we have developed a quantitative, psychophysically based model (Multidimensional Phoneme Identification, MPI) of phoneme perception by CI users [M. A. Svirsky and T. A. Meyer, J. Acoust. Soc. Am. 103, 2977 (1998)]. The MPI model generates phoneme confusion matrices from performance on psychophysical tasks. In a complimentary line of work, we aim to predict open-set spoken word recognition from phoneme performance [S. Frisch and D. B. Pisoni, Res. Spoken Lang. Proc. 261–288 (1998)]. In both lines of research, we have found predictable relations between perception of phonetic features, phonemes, and words by CI users. [Work supported by NIH, AAO-HNS, DRF, NOHR.]
Measurements of the dynamic elastic moduli of viscoelastic materials with micro-inclusions
Authors: Willis R. Lance , Wu Lei , Berthelot Yves H.
Published: July 2002

An indirect method has been proposed [see J. Acoust. Soc. Am. 102, 3549–3555 (1997)] to determine the complex, frequency-dependent, elastic moduli of polymers containing microscopic inclusions from laser-based measurements and finite element modeling. The method consists in measuring the surface dynamics of the sample under harmonic excitation by noncontact laser Doppler interferometry. The experimental results are then matched with numerical predictions in which the moduli are the adjustable parameters. The method is first validated at ambient pressure by measuring the dynamic moduli of a sample of known properties. Results obtained with samples of the same voided viscoelastic material but with different aspect ratios are presented. To assess the effect of static pressure on the moduli, the sample is placed inside a static pressure air chamber (0–500 psi) and the effect of pressure cycling is investigated by measuring the moduli during the first pressure cycle (0–500, and 500–0 psi) and after eight pressure cycles. [Work supported by ONR, code 334.]
Thermoelastic effects on surface acoustic wave propagation
Authors: Yan Zhongyu , Nagy Peter B.
Published: July 2002

The effect of thermal stresses on ultrasonic surface wave propagation was investigated. Quasi-static and dynamic thermal stresses and deformations were considered in materials with and without fatigue cracks. The perturbation of ultrasonic surface waves due to these thermal effects were studied both theoretically and experimentally. A long-duration infrared laser pulse was used to irradiate a series of aluminum and titanium specimens with fatigue cracks of known sizes between 0.5 and 1.0 mm. Preliminary numerical results from finite element simulation were found to be in good agreement with the experimentally observed laser-induced modulations of the ultrasonic surface wave. In particularly, both the numerical and experimental results indicated the same characteristic transient behaviors of the thermo-optical modulations for cracked and intact materials. The different behaviors suggest a new promising method for ultrasonic nondestructive evaluation, which cannot only effectively distinguish fatigue cracks from other artifact scatters, but potentially can also provide a method for quantitative evaluation of crack features. [This effort was sponsored by the Defense Advanced Research Project Agency (DARPA) Multidisciplinary University Research Initiatiative (MURI), under Air Force Office of Scientific Research Grant No. F49620-96-1-0442.]