bluuebunny/crossref_metadata_2025 huggingface dataset:
TRISTEN/FRAM IV cw spatial coherence and temporal stability
Authors: DiNapoli F. R. , Nielsen R. , Potter D. , Stocklin P. L.
Published: January 2006

The TRISTEN-82/FRAM IV experiment was a multifaceted experiment investigating acoustics in the Arctic. This paper focuses on the spatial coherence and temporal (frequency) stability of acoustic signals transmitted and received between fixed ice camps separated by approximately 130 nmi. A high-powered, low-frequency (NUSC HLF-3 Arctic) hydroaroustic source transmitted stable cw tones of 1 h or more at various frequencies from 5 to 200 Hz during April 1982. These signals were received on an X-shaped array having an aperture of 1200 m on each leg. The army was operated by the Massachusetts Institute of Technology and the Wood Hole Oceanographic Institute. The spatial coherence, both broadside and end-fire to the source were found from normalized sensor pair cross correlation, corrected for signal-to-noise ratio. Total and 3-dB down received signal bandwidths were found using complex demodulation and FFT with a resolution to a fraction of mHz, followed by cumulative energy analysis in the frequency domain. The experimental setup data, analysis procedures, and results will be presented. [Work sponsored by the Office of Naval Research, Code 425-AR.]
Arctic data collection the easy way—Data buoys
Authors: Buck Beaumont M.
Published: January 2006

This paper presents a review of developmental and operational use of Arctic data buoys. There are many problems involved with aircraft and icebreaker logistics for scientific support in the Arctic. Manned research stations on sea ice are expensive, self-contaminating in terms of acoustic and electromagnetic noise, and generally limited to a 40- to 50-day period in the springtime. Autonomous data buoys, on the other hand, do not suffer those limitations. These devices can be installed by paradrop, aircraft ice-landing, submarine, or ice-breaker in almost any geographic area of the Arctic Ocean, peripheral seas, and marginal sea ice zones to collect and report data over all seasons. There are restrictions, of course, as to what can be accomplished automatically within a small buoy hull, and almost all Arctic buoys, so far, have been mechanically passive. Recent advances in low-power microprocessors and memories enable considerable increases in the extensive in-buoy processing needed for data compression to accomodate the limited capacities of polar orbiting scientific satellites. [Work supported by U.S. Navy and NOAA.]
A syllable-based connected-digit recognizer for telephone speech
Authors: Kahn D.
Published: January 2006

This paper describes a system for the automatic recognition of digits spoken in connected strings. The input is standard telephone-quality audio, bandlimited to 200–3200 Hz, spoken in a room with a background noise level of 60 dBA. The first step performed is a segmentation of the incoming string into syllables. Important features of the syllabification algorithm [D. Kahn, J. Acoust. Soc. Am. Suppl. 1 73, S88 (1983)] are (a) the analysis is based solely on the energy contour, with no spectral information, and (b) syllables judged to be unstressed are appended to the preceding stressed syllable; this is relevant only in the case of “seven,” and results in the syllabic analysis being equivalent to a segmentation into digits. The remaining analysis centers around an Itakura-type dynamic-programming match between each extracted segment and a set of stored digit templates. The templates are themselves derived from segments extracted from telephone-quality connected-digit strings.
A portable phonetics laboratory
Authors: Javkin Hector , van der Veen Robert
Published: January 2006

PIPS (Portable Instrumental Phonetics Station) is a portable box designed for gathering and analyzing aerodynamic and other phonetic data in the field. It contains two pressure transducers mounted 10 cm apart in a single tube with accompanying amplifiers, a high-speed chart recorder, a Rothenberg airflow measurement system, and a miniature storage oscilloscope. Circuits constructed at UCLA provide (1) preamplification to strengthen weak signals, (2) amplification to drive the chart recorder galvanometers (3) rms energy envelopes of ac signals, and (4) FM modulation and demodulation that can record and play back one channel of relatively high-frequency data or two channels of low-frequency data on a single track of a portable tape recorder. An experimenter normally uses the other track of a stereo tape recorder for an audio recording, although the two types of FM encoders can be used simultaneously to provide up to three channels of FM recording on a stereo tape recorder. Rechargeable batteries can drive most of the circuits. At present, the PIPS has been used in the U.S., China, and the Southern Sudan. [Work supported by NIH and NSF.]
Digital signal processing and auditory physiology
Authors: Allen J. B.
Published: January 2006

Digital signal processing techniques are very important to the area of auditory neurophysiology since the auditory signals must be carefully controlled and because the data collection paradigms are frequently quite complicated. in this talk I shall describe a computer system that is jointly used by Bell Labs and Columbia Presbyterian Hospital. Key issues include methods for real-time data acquisition at 10-μsec rates while running a full operating system on the host computer, D/A and A/D hardware which produce less than 0.01% distortion for single tone signals, real-time linear system identification methods, and acoustic impedance measurement methods.
Applications of digital signal processing in computer music
Authors: Loy Gareth , Dolson Mark
Published: January 2006

Recent developments in signal processing have opened many new lines of inquiry in computer music. Areas where signal processing techniques are appropriate include measurement and observation, signal representation, transformation, analysis, and synthesis of musical sound. Topics addressed in this paper include representational requirements for music, segmentation and analysis techniques such as linear predictive coding, the phase vocoder, data reduction, filtering, and synthesis. Examples will be given within the context of a digital signal processing paradigm developed at C.A.R.L. that tightly couples the facilities of UNIX operating system with research tools for computer music.
Effect of presentation level on the SSW test with hearing-impaired adults
Authors: Flynn Patricia A. , Danhauer Jeffrey L. , Arnst Dennis J. , Goller Monica C. , Gerber Sanford E.
Published: January 2006

The effects of varying presentation level on the Staggered Spondaic Word (SSW) test scores of sensorineural hearing-impaired subjects were investigated. Subjects were 15 adults having cochlear hearing losses between 30 and 50 dB (re: PTA). Performance-intensity (PI) functions were generated using subjects SSW test scores. Each subject received all 40-SSW test items, but the PI functions were generated by presenting items numbered 1–10 at 20 dB SL (re: three frequency PTA); 11–20 at 30 dB SL; 21–30 at 40 dB SL; and 31–40 at 50 dB SL. These results for the hearing-impaired were compared to functions reported earlier for normal subjects [P. C. Doyle, thesis, University of California, Santa Barbara (1981)]. The PI functions were analyzed for “competing” versus “noncompeting” conditions, and differences between subjects' raw SSW scores and word discrimination scores as a function of presentation level. Practical and theoretical implications for the clinical presentation of the SSW test at the various intensity levels to hearing-impaired adults are discussed.
The electrically induced auditory brainstem response in the guinea pig
Authors: Brown D. D. , Miyamoto R. T.
Published: January 2006

The cochlear implant is a clinically useful prosthesis for selected deaf patients who cannot benefit from a hearing aid. However, the poor speech discrimination and limited dynamic range generally achieved with the implant indicate that there are a number of basic and applied questions to be answered. Using acoustically and electrically elicited Auditory Brainstem Response (ABR) techniques, we have established an animal model (guinea pig) to help us answer some of these questions. We are presently studying the effect of electrode location on the electrical ABR. The single active cochlear electrode is located in either the basal or apical turn. The return electrode locations are the temporalis muscle, the eustachian tube, or the bulla. By choosing the proper polarity of the biphasic stimulating pulse, the electrical artifact can be minimized and virtually all of the ABR can be observed. Normative data for the electrical ABR and preliminary results of the electrode placement study will be presented.
Choice of stimulus parameters for measurement of auditory functions
Authors: Wightman Frederic L. , Raz Israel , Velde Therese M. , Grose John H.
Published: January 2006

As a preliminary to a large-scale study of the interrelations among several auditory abilities, we conducted a separate experiment in order to determine which stimulus conditions would best discriminate among subjects. Using a forced-choice forward masking paradigm in all conditions, we obtained, from 12 normal listeners, eight 6-point psychophysical tuning curves with probe frequencies from 500 Hz to 4 kHz, two 10-point unmasking patterns (one each at 1 and 3 kHz), and two 4-point functions relating combination-tone (2f1-f2) level and f2/f1 ratio (one each at 1 and 3 kHz). Data from individual subjects were fit with low-order polynomials, and the coefficients of these polynomials were entered into an analysis of variance. The major conclusions which arose from this analysis are: (1) Frequency resolution, to the extent it is characterized by forward-masked PTCs, is adequately represented by two six-point PTCs, one at 1 and one at 3 kHz. (2) Two-tone unmasking is independent of frequency, and thus one unmasking pattern, at either 1 or 3 kHz can be used to represent unmasking. (3) Combination-tone generation is also independent of frequency, so the slope of only one CDT vs f2/f1 function, at either 1 or 3 kHz, can adequately characterize CDT generation. [Work supported by NINCDS.]
Relations among auditory functions in normal listeners
Authors: Raz Israel , Wightman Frederic L. , Grose John H. , Velde Therese M.
Published: January 2006

The interrelations among frequency selectivity, nonlinearities, and speech perception in noise were examined in 24 normal-hearing young adults. Measures of psychophysical tuning curves, suppression (as indicated by the extent of unmasking caused by several suppressors), and the audibility region of 2f1-f2 were obtained with an adaptive forward-masking detection paradigm. Speech perception in noise was evaluated with the nonsense syllable test via a computer-controlled (“best of three”) adaptive procedure. The relations among functions were traced with multivariate analytic techniques. Based on these analyses, we conclude that: (1) Sharpness of tuning is intimately related to Combination Tone Generation (CTG) but not to suppression. (2) CTG is not related to suppression. (3) Aspects of speech perception in noise can be accounted for by information on frequency selectivity and nonlinearities. [Work supported by NINCDS.]
A description of surface-wave scattering using a stepwise coupled-mode approach
Authors: Feuillade C.
Published: January 2006

We have extended the method of stepwise coupled modes to describe propagation through a medium of variable depth due to surface waves. This facilities the modeling of acoustic scattering from a rough surface. The method may be applied to describe scattering within a waveguide with a rough surface, or to model energy losses due to scattering out of a surface duct. Numerical procedures have been codified to solve the equations resulting from the analysis and some examples are provided.
Some similarities in community response to aircraft and road traffic noise
Authors: Fidell S.
Published: January 2006

A Social survey was undertaken in the vicinity of a major air carrier airport. One of the two neighborhoods was exposed to noise due to aircraft operations at about Ldn = 70 dB. The other neighborhood was exposed to road traffic noise at about Ldn = 62 dB. A brief structured interview conducted by telephone revealed a number of similarities in community response to the two noise exposure environments. These included reports of sleep interference and habituation to noise exposure. Differences in observed prevalence of annoyance in the two neighborhoods were attributable to the differences in exposure levels.
The effect of curved vehicle path on average sound pressure level
Authors: Davis Gregory S. , Wallace C. E.
Published: January 2006

A mathematical theory is presented which predicts average noise levels for curved aircraft flight paths. The error in computing equivalent noise levels by assuming a straight flight path and then bending it to follow the curved flight path is evaluated as a function of the shape of the curved flight path and the location of the observer. The theory is experimentally verified using an automobile on a curved test track. It is shown that for a given observer location, the amount of error increases as the amount of path curvature increases. Also it is shown that for a given curved path, the amount of error increases as the observer location is moved away from the curved path. In some cases the error incurred is significant and is in excess of 3 dB.
Removal of the assumption of plane primary waves in the theory of the nonscattering of sound by sound
Authors: Westervelt Peter J.
Published: January 2006

The virtual source of combination frequencies is well known to be Q = β(∂/∂t)(p1p2), where β = ρ0−2c0−4 [2 + (d2p/d ρ2)ρ0] and the pressure of each of the two primary waves may be expressed as p1 = a1 cos ψ1, and p2 = a2 cos ψ2, where the a's and the eikonals, the ψ's, depend on the four-radius vector xi (refer to “eikonal” in the index of any late edition of Landau and Lifshitz, The Classical Theory of Fields). The restriction to plane primary waves implicit in my derivation of Q [J. Acoust. Soc. Am. 35, 535–537 (1963)] was later removed by me [Proc. Univ. of Texas Nonlinear Acoustics Symposium, edited by T. G. Muir, pp. 167–181 (1970)]. The present paper reports a function R whose d'Alembertian equals Q when the region of interaction common to both primary waves resides many primary wavelengths from each of the two sources. It turns out that R = 12β(∂/∂t) [a1a2[(∂ψ1/∂xi)(∂ψ2/∂xi)]−1sin ψ1 sin ψ2] in which (∂ψ1/∂xi)(∂ψ2/∂xi) means ∇ψ1⋅∇ψ2 − c0−2ψ1ψ2. Thus ∇2R − c0−2 R = Q plus terms that are negligible if the primaries are not collinear since these terms are of order E−1 and E−2 smaller than Q where E = ψ + iωt is the space-only dependent eikonal. E1 and E2 have magnitudes of the order r1 λ1−1 and r2λ2−1, respectively, where r1 and r2 are the distances from the interaction region to the primary sources of waves having dominant wave-lengths λ1 and λ2, respectively. The conclusion is that no scattering occurs outside the interaction region of two waves, neither one of which needs to be strictly plane, nor for that matter steady state.
Analysis of acoustically excited structures using holographic interferometry with thermoplastic films
Authors: Clark Joseph A.
Published: January 2006

Experimental studies of the transient and modal response of vibrating bodies excited by sound fields will be described. Reusable thermoplastic film is utilized with an automated hologram recorder in order to more conveniently obtain real-time and time-average holograms. This approach facilitates interactive analysis and design of vibrating structures. Typical structures being currently studied are membranes excited both resonantly and nonresonantly by airborne sound. Membrane structures appropriate for spatially resolved measurements of radiating sound fields and turbulent boundary pressure fields will be discussed. [Research sponsored by O.N.R. and D.T.N.S.R.D.C.]
Experimental study of internal noise on a shell submitted to boundary layer excitation
Authors: Larcher Jacqueline , Parot Jean-Marc , Berhault Jean-Paul
Published: January 2006

A study has been done of the acoustic performance of elastic material shells, surrounded by a heavy fluid, submitted to a turbulent boundary layer excitation. Measurements of internal noise levels under localized excitation, in frequency bands, show good agreement with the result given by a statistical energy model. These results show significant effects of the structural properties and material for a given shell shape. The results agree well with noise and vibration measurements in a reciprocity situation (action of an internal noise source on the structure). Flexural waves in the shell material, although subsonic, play a major role.
Experimental investigation of nonlinear crossed beam scattering in the presence of turbulence
Authors: Korman Murray S.
Published: January 2006

An experimental apparatus has been constructed to measure the nonlinear scattering of two mutually perpendicular crossed sound beams in the presence of turbulence (from a submerged water jet). Results are used to measure and characterize the turbulent flow. The pulsed beams (1.90 and 2.10 MHz) are generated from 1-in.-diam transducers, suspended from perpendicular radius arms that are free to rotate 360° in a horizontal plane. The transmitters and 4-MHz receiver are located 1 and 2 m from the interaction region, respectively. One experimental difficulty is the inability to distinguish between scattering from the interaction region and other nonlinear processes. As part of the calibration procedure the nonlinear scattering of a cylinder is investigated. Measurements show that scattering at angles near the main primary lobes are extremely difficult to measure due to the inability to separate out the scattered field of (a) one primary beam interacting with (b) the scattered linear field of the other primary beam from the cylinder. Preliminary results from the scattering by turbulence and by a cylinder will be presented. [Work supported by NRL (Physical Acoustics Branch) and USNA.]
On the construction of linear-response hydrophones
Authors: Moffett Mark B. , Henriquez Theodore A. , Miller Mary Lou
Published: January 2006

Most hydrophone elements in use nowadays can be classified either as volume-mode elements or as piezoceramic elements. Although volume-mode elements are usually quite linear, nearly all have low capacitance, and so, in practice, are used in conjunction with preamplifiers. Preamplifiers, however, can be nonlinear and are not usually suitable for close-range parametric source measurements. Piezoceramic elements have high capacitances and therefore can be used without preamplifiers. However, they do not work well in the volume mode, and so they are usually configured so as to expose only one element surface to the acoustic pressure. Such configurations invariably require bonds of some sort, e.g., two ceramic hemispheres are glued together to form a spherical hydrophone. Nonlinearity of an epoxy bond appears to account for the nonlinearity of F42D spherical hydrophones. Linear-response hydrophones suitable for use with parametric sources at close range can be constructed with volume-mode elements. If cable lengths can be kept short (⩽ 10 m), no preamplifier should be used. Otherwise a passive low-pass filter should precede the preamplifier. [Work supported by Naval Material Command and Naval Sea Systems command.]
Status of standards on digital systems for sound and vibration analysis
Authors: Embleton Tony F. W.
Published: January 2006

Existing ANSI (American National Standards Institute) standards deal primarily with analog acoustical instruments and their use—following traditional thinking and procedures of acousticians. They are relevant to the analog parts of a digital signal processing system such as the signal itself (time and frequency characteristics), transduction (directionality, linearity, frequency response of microphones or vibration pick-ups), and output (preferred frequencies, reference quantifies). They are also relevant to digital components that mimic closely the behavior of analog devices, e.g., filters that receive signals continuously. The next revision of S1.11 will explicitly include specifications for the performance of both analog and digital filters. The IEC (International Electrotechnical Commission) acoustical standards similarly relate to analog instruments and their use. The next several years should see progress in the development of standards for digital acoustical instrumentation, but before this can happen acousticians must recognize and widely discuss the technical problems that exist. General consensus should be reached on many factors, one of the most fundamental is the possible methods of achieving a desired degree of accuracy for a given kind of acoustical signal. Standards written prematurely risk biasing measurement procedures, and instrumentation to meet these needs, in what may be less-than-optimum directions.
Behavioral and physiological responses of captive beluga whales to playbacks of drilling noise
Authors: Thomas Jeanette A. , Kastelein Ronald
Published: January 2006

There has been recent concern that noise from drilling platforms may have detrimental effects on marine animals. Unfortunately, little data are available on the hearing capabilities of marine mammals and their responses to man-made noise. The objectives of our study were to playback underwater recordings of drilling noise to captive beluga whales and assess: (1) behavioral responses such as respiration rate, dive interval, changes in social combinations, and change in usage of areas in the pool, and (2) physiological responses monitored by changes in blood chemistries, especially cetecholamine levels. Baseline behavioral and blood values were collected for two males and two females housed at Sea World, San Diego for a 30-day period. Playbacks were conducted for 9 days preceded by pretest observations. The playbacks were recordings of SEDCO 708 platform and synthesized drilling noise projected at about 150 dB re: μPa. The manner in which behavioral parameters and blood chemistry values changed during the playbacks of drilling noise will be discussed.
Acoustic testing procedures for determining the potential impact of underwater industrial noise on migrating gray whales
Authors: Malme Charles I. , Miles Paul R.
Published: January 2006

A procedure was developed for observing the track patterns and behavior of migrating gray whales off Soberanes Point south of Monterey, California. A series of acoustic playbacks were made at realistic levels from an anchored vessel to simulate the presence of oil and gas development and production activities. In another series of tests, a seismic survey vessel with a 4000-in.3 air-gun array was navigated at progressively decreased ranges from the migrating whales. This was followed by a test sequence using a vessel with a single 100-in.3 air gun. Source characteristic and acoustic transmission loss measurements were made to permit prediction of the noise exposure for the nearby subject animals. Exposure levels for which observed behavioral changes occurred were determined. [Work supported by Dept. of Interior, Minerals Management Service.]
Effects of underwater noise on migrating gray whales off the coast of California
Authors: Clark Christopher , Tyack Peter , Bird James , Rowntree Victoria
Published: January 2006

The potential effects of man-made underwater noises on the behavior of gray whales (Eschrictius robustus) off the Coast of central California were studied during their southern and northern migration in 1983. In January, two shore-based theodolite tracking sites recorded whales' swimming patterns as well as behavioral activities while underwater sounds (production platform, drilling platform, semisubmersible, drillship, helicopter, or killer whale, Orcinus orca) were transmitted from a vessel anchored in the middle of the nearshore migratory pattern. In April and May, when the majority of whales were mother-calf pairs, three theodolite tracking sites recorded swimming patterns, behavior, and respiration times for individuals. Experimental noise sources consisted of either a seismic vessel operating a 40-gun array, a vessel operating a single air gun or a stationary vessel broadcasting either drillship or killer whale sounds. The behavioral measures used to assay disturbance included deflection of normal migratory pattern, speed of travel, individual respiration, synchronizing of mother and calf respiration, and rates of behaviors such as breaching or underwater expiration. [Work was supported by Minerals Management Service.]
Interaction between offshore geophysical exploration activities and bowhead whales in the Alaskan Beaufort Sea, Fall 1982
Authors: Ljungblad Donald K.
Published: January 2006

Out of concern about the potential effects of marine acoustic geophysical survey work on westward-migrating bowhead whales (Balaena mysticetus), the U.S. Minerals Management Service (MMS), in consultation with the U.S. National Marine Fisheries Service (NMFS), implemented a program for monitoring and regulating such work in the Alaskan Beaufort Sea during 1981 and 1982. In 1982 a twin-turbine, high-wing aircraft was used to survey systematically blocks covering approximately 1400 km2 near actively “shooting” seismic survey vessels. Direct visual observation was supplemented by the use of sonobuoys to listen to and record underwater sounds made by vessels, air guns, and whales. In addition to the systematic surveys, sustained behavioral observations of bowheads were made on an opportunistic basis, with the objective of identifying possible differences in behavior between whales exposed to seismic sounds and whales not exposed to seismic sounds. No major changes in whale behavior (e.g., flight reactions) were observed. Tests of statistical significance were applied to data on number of blows per surfacing, mean blow interval per surfacing, surface times, and dive times. Only mean surface time of “adults” (i.e., all whales other than cows and calves) in the presence and absence of seismic sounds (1.67 ± s.d. 0.85 min and 1.36 ± s.d. 0.59 min, respectively) was statistically significant (t = 1.988, df = 89, p < 0.05). No statistically significant differences were detected for other behavioral parameters in the presence and absence of seismic sounds.
On the drag and virtual mass coefficients in Biot's equations
Authors: Bedford A. , Stern M. , Costley R. D.
Published: January 2006

Consider a hypothetical experiment in which the solid constituent of a fluid-saturated porous medium is subjected to a uniform oscillatory motion. Biot's equations can be solved for the drag and virtual mass coefficients in terms of the resulting oscillatory motion of the fluid. Assuming the pores to be cylindrical, the motion of the fluid has been determined by subjecting the wall of a cylinder of viscous compressible fluid to a uniform oscillatory motion and averaging the resulting fluid displacement over the volume of the cylinder. Motions parallel to and normal to the axis of the cylinder have been considered. In the case of motion parallel to the cylinder axis, the obtained coefficients are equivalent to those derived by Biot [J. Acoust. Soc. Am. 28, 179–191 (1956)] and Hovem and Ingram [J. Acoust. Soc. Am. 66, 1807–1812 (1979)]. By superimposing the parallel and normal cases, the coefficients for cylindrical pores at an arbitrary angle to the propagation direction have been obtained. Then, by averaging with respect to the angle, the coefficients have been determined for a material containing pores of random orientation. [Work supported by the ONR.]
Estimation of the components of anisotropic permeability from observations of acoustic anisotropy
Authors: Adams Wm. Mansfield , Wheatcraft Stephen W. , Hess John W.
Published: January 2006

Decisions on positioning of monitoring wells in the vicinity of hazardous waste sites can be significantly affected by knowledge of the natural anisotropic hydraulic conductivity. That the vertical permeability is usually less than the horizontal permeability is well known: however, the anisotrophy in the horizontal plane may influence the choice of positions for those monitoring wells that are downgradient from the waste-management area. Very little information on the horizontal anisotropy is available. Furthermore, field measurements to estimate the horizontal anisotropy are expensive because at least three interacting wells are necessary, with more than three being preferred. The Kozeny equation suggests that directional anisotropy of the electrical conductivity of a porous media should correlate closely with the anisotropy of the permeability [S. J. Pirson, Geological Well Log Analysis (Gulk Publ. Co., 1981), p. 135]. A close relationship should also exist between the acoustic anisotropy and the anisotropy of the permeability. Recent advances in techniques for measuring acoustic velocities in a borehole make it feasible to obtain estimates of the anisotropy of the permeability from observations of the anistropy of the seismic velocities. [Work supported by EPA.]
Coupling of airborne sound into the porous elastic surface of the Earth
Authors: Bass Henry E. , Bolen Lee N. , Sabatier James M
Published: January 2006

The surface of the Earth can be modeled as an elastic medium permeated with pores. This porous nature has enabled prior investigators to explain measurements of sound propagation in the vicinity of the Earth by describing the surface as a locally reacting boundary. Physically, one can envision the pressure variations associated with sound wave passage forcing air flow in the pores. Some of this energy is lost to the pore walls due to viscous drag and thermal conduction. Viscous drag causes the solid skeleton to move giving rise to a seismic wave in the frame. This wave has been measured with geophones. This physical description conforms well to Biot's description of sound waves in a porous medium and that theory has been used to model the coupling process. Specifically, the complex propagation constants have been calculated using a code developed by Attenborough which includes pore tortuosity and these propagation constants have been used to compute geophone and buried microphone response in a porous medium below an air half space and above an elastic lower half space. Computer response will be compared with measurements reported earlier. [Work supported by ARO.]
Some remarks on electro-mechano-acoustical circuits
Authors: Beranek Leo L.
Published: January 2006

The advanced development of electro-mechano-acoustical circuits dates in the USA from Firestone (1933), Mason (1941), Olson (1943), Le Corbeillier and Yueng (1952), Bauer (1953), and Beranek (1954). Although the connection between the equations of radio and acoustic wave motion was clearly recognized by Helmholtz and pointed up by Rayleigh, the use of lumped-element circuits was brought on by the advent of radio. Significant use of electrical (radio) analogies was made by Darrieus (France, 1929) and Haehnle (Germany, 1932). This paper treats the period in which Olson's work was centered and cites some examples of product development that were influenced by the concepts of electro-mechano-acoustical circuits.
Spatial transformation of sound fields
Authors: Hald Jørgen , Roth Ole
Published: January 2006

In this paper it will be demonstrated how cross spectra measured by a modified 1/3 octave realtime intensity analyzer during a planar scan can be used to predict pressure, particle velocity, and intensity in a half-space not containing the source of the (noise) field. We just have to assume a rather limited number of significant uncorrelated components in the total source. In the nearfield region on both sides of the scan plane the field quantities are evaluated using a nearfield holography technique similar to the technique described by Williams, Maynard, and Skudrzyk [J. Acoust. Soc. Am. 68, 340–344 (1980)] for analysis of coherent sound fields. Outside the nearfield region Helmholtz' integral equation is used for the prediction. The combined method allows various simulations to be carried through. For example we can estimate a planar source distribution by means of the holography method, simulate an attenuation of some part of the source, and investigate the effect of this attenuation on the field in the entire source free half-space.
A transducer and processing system to measure total acoustic energy density
Authors: Schumacher Marc , Hixson Elmer L.
Published: January 2006

A four-microphone orthogonal array is used to determine the acoustic pressure and the three components of acoustic velocity over the range of 300–3000 Hz. Signals are squared and summed to produce potential, kinetic, and total energy density. The three components of the intensity vector can also be determined. The device has been designed for the study of and improved measurements in reverberant and partially reverberant sound fields. Some preliminary measurements in a reverberation room will be presented. [Work supported by IBM Corp., Communications Products Div., Austin, TX.]
Best estimates of initial decay rates in reverberation rooms
Authors: Guernsey Richard M.
Published: January 2006

The desideratum in laboratory decay measurements is to get a good estimate of the decay rate of the reverberant field immediately after the source is turned off. When a decay is the superposition of two or more modes with different decay rates the level is not a linear function of time. Thus we want to detect a curved decay and make a best estimate of its initial decay rate. Currently, a real time analyzer controlled by a digital computer provides the best practical measurement of decays. A linear, first order regression is fitted to the ensemble average of a suitable number of decay measurements. Suggestions by Bodlund; Halliwell and Warnock; and Bartel for detecting curved decays are evaluated. Two additional methods are proposed. It is demonstrated with the help of statistically simulated, curved decays that a second-order, linear regression provides a better estimate of the initial decay rate than a first order regression; the penalty in calculation time is not severe. Guidelines for future investigations are proposed.
Comparison of impedance measurement techniques
Authors: Mason J. T. , Mills G. B. , Garrett S. L. , Wayman James L.
Published: January 2006

The acoustic impedances of a Helmholtz resonator and porous materials were measured using two different techniques. The first method used the conventional Standing Wave Ratio technique. The second was the two-microphone technique of Chung and Blaser [J. Acoust. Soc. Am. 68, 907–921 (1980)]. The calculability of the frequency dependent Helmholtz resonator impedance allowed the methods to be compared for both absolute accuracy and realtive precision. [Work supported by the NPS Foundation Research Program.]
Effect of sealants on the sound absorption coefficients of acoustical friable insulating materials
Authors: Lory Mary K. , Wayman James L.
Published: January 2006

Acoustical friable insulating materials (AFIM), which often in the past have contained asbestos, have been used for sound control since the mid-1930s. Because of their widespread use and the ease of fiber dissemination, friable asbestos materials are considered to be the major source of asbestos fiber contamination in the indoor environment. Encapsulation of asbestos materials with a commercial sealant product is one of several methods used to control potential asbestos exposure in rooms. A sealant product that preserves most of the acoustical properties of the material is preferred in this usage. In this study, AFIM sample materials were treated with six types of sealants and the effects on normally incident absorption coefficients from 100–2500 Hz were measured using a fixed, dual-microphone technique. “Penetrating” type sealants were found to have a less detrimental effect on sound absorption than those of a “bridging” type.
The BER, masking, and cochlear place
Authors: Burkard Robert , Hecox Kurt
Published: January 2006

Two experiments concerning the effects of masking on the brainstem evoked response (BER) are reported. The first experiment evaluated the effects of noise level and rate on waves I, III, and V. There was an increase in peak latencies and a decrease in peak amplitudes with increasing noise level and rate. Higher noise levels and rates increased the I–V interval, and produced a greater increase in the III–V than the I–III interval. The second experiment used the high-pass subtractive-masking technique and covaried derived-response bandwidth and within-band noise level. For half-octave derived bands, the within-band wave V latency at higher noise levels was greater than the unmasked latency of the immediately apical band. The magnitude of within-band noise-induced wave V latency shift was independent of response bandwidth. The relatively large within-band noise-induced wave V latency shift combined with the increasing I–V interval with increasing noise level suggest that a shift in cochlear region of response emanation is not responsbile for most of the wave V latency shift with increasing noise level. [Work supported by NIH.]
The effects of signal/masker phase conditions on the late cortical response
Authors: Schaefer Amy B. , Martinez Charles D. , Noffsinger Douglas
Published: January 2006

Previous investigations have produced indirect evidence of a coherent relationship between the presence and magnitude of the binaural masking level difference (MLD) and the pattern of monaural early auditory brainstem potentials exhibited by the same subjects. This investigation sought electrophysiologic changes corresponding to the presence or absence of behavioral MLD by monitoring via surface electrodes the late cortical potentials (P1, N1, P2, N2) aroused by signal/masker configurations known to produce an MLD. Tonal stimuli of 500 and 2000 Hz were presented binaurally along with binaural narrow-band noise centered at the test frequency under SoNo and SπNo signal/masker phase conditions. Twenty-five young (X̄ age: 24.6 yrs) normal-hearing subjects with normal ABR for 2000- and 4000-Hz tone pips and normal 500-Hz behavioral MLD were tested. A consistent and statistically significant increase in the amplitude and/or reduction in the latency of onset of the cortical potentials was evidenced for 500-Hz stimuli for the SπNo condition when compared to the SoNo condition. Such changes did not occur in response to 2000-Hz stimuli. [Work supported by NIH.]
Identification of transition frequency and duration changes in synthetic speech as a function of hearing status and age
Authors: Ivory Peter J. , Brandt John F.
Published: January 2006

The identification of synthetic speech syllables which incorporated identical formant transition frequency changes in three different transition duration contexts (40, 120, 240 ms) or which incorporated identical transition duration changes in three different transition frequency contexts (where F2 locus was 800, 1520, or 2120 Hz) was assessed for young and old normal-hearing and sensorineurally hearing-impaired listeners. The older listeners, independent of hearing-impairment, demonstrated a significant decrement in identification performance for all experimental continua. The hearing-impaired listeners, independent of age, demonstrated a significant decrement in identification performance for most, but not all, experimental continua. Specifically, identification of syllables incorporating frequency changes was not significantly affected in the 240-ms duration context but significantly poorer in the contexts utilizing the two shorter transition durations. Furthermore, identification of syllables incorporating duration changes was not significantly affected in the 800-Hz transition locus context but significantly poorer in the higher frequency contexts.
Judging sine wave stimuli as speech and as nonspeech
Authors: Williams David R. , Verbrugge Robert R. , Studdert-Kennedy Michael
Published: January 2006

Interest in the perceptual equivalence of “static” and “dynamic” stimuli spans both speech and nonspeech domains. Previous investigations of speech stimuli have shown that, given matched sets of three-formant steady-state vowels and vowels flanked by consonantal transitions, phonetic equivalence is not defined by equal position along the two continua [B. Lindblom and M. Studdert-Kennedy, J. Acoust. Soc. Am. 42, 830–843 (1967)]. For judgments of relative pitch, on the other hand, ramp tones are judged to be nearly equivalent in pitch to steady-state tones at their endpoint frequencies [P. T. Brady et al., J. Acoust. Soc. Am. 33, 1357–1362 (1961)]. The present set of experiments demonstrates this difference in categorization of static and dynamic stimuli using a single type of stimulus. Two sets of sine wave stimuli (FLAT/CONTOUR) were constructed by modeling the frequency and relative amplitude characteristics of the aforementioned speech stimuli. When judged in terms of phonetic categories (/ᴜ/ vs /ɪ/), significantly greater proportion of /ᴜ/ judgments were observed for the FLAT than for the CONTOUR continuum. However, when the same two sets of stimuli were judged in terms of relative pitch (HIGH versus LOW), no significant difference in response pattern for the two continua was noted. Thus the experiments demonstrate that two distinct response patterns may be elicited for sine wave stimuli contingent only on the experimenter's instructions. [Work supported by NICHD.]
Perception of “modulation” in speechlike signals II: Discrimination of frequency extent as a function of spectral content and direction of change
Authors: Miller Creighton J. , Porter Robert J.
Published: January 2006

This is the second in a series of studies designed to evaluate listeners' perception of modulation in speechlike signals [R. Porter and C. Miller, J. Acoust. Soc. Am. Suppl. 1 73, S3 (1983)]. The study examines discrimination of second formant stimuli whose center frequency traversed a single 120 ms haversine modulation at their midpoint. Extent of frequency change for the stimulus set was varied in 20-Hz steps across the range, 100–400 Hz, both above and below the steady-state value of 1232 Hz. Separate continua were generated with and without the presence of a 769-Hz first formant. Paired comparison discrimination tests were conducted with listeners trained to judge which of the stimuli changed most. Results will be discussed in terms of their relation to the modulation percept, and to prior results of other investigations which have studied the perception of second formant transitions in and out of speech contexts. [Supported in part, by NINCDS NS ♯11647, The Louisiana Eye and Ear Foundation, The Louisiana Lions, and The Kresge Foundation.]
Sensitivity to rate-of-change of frequency transition
Authors: Jamieson Donald G. , Slawinska E.
Published: January 2006

We examined a possible psychoacoustic basis for the relatively invariant duration over which the rapid formant frequency transitions cueing place of articulation occur in initial-position stop consonants such as /ba/. Our stimuli consisted of a 200-ms duration compound of a pure-tone frequency glide followed by a steady-state pure-tone stimulus. Glides covered a fixed range of frequencies (400–700 Hz; 1500–2200 Hz; or both together) over a variable interval of time (10–90 ms, in 10-ms step). Three experiments examined discrimination performance in an AX paradigm; on any trial X = A or X = (A ± one step in a stimulus series). In each experiment, discriminability (−lnμ) tended to achieve a maximum, and bias (lnβ) tended to achieve a minimum, when the transition occurred over 50 ms. These results support and extend earlier reports [A. Nabelek and I. Hirsch, J. Acoust. Soc. Am. 45, 1510–1519 (1969)] and appear to reflect a special perceptual sensitivity to frequency changes which occur within the 40–60-ms interval of time typical for the analogous transitions in natural speech. [Work supported by NSERC and AHFMR.]
Fundamental frequency and the comprehension of simple and complex sentences
Authors: Larkey Leah S. , Danly Martha
Published: January 2006

The intelligibility of sentences with monotone fundamental frequency was assessed using a sentence verification paradigm, which measured listeners' reaction time in judging whether a sentence was true or false. A zero-phase vocoder was used to allow manipulation of fundamental frequency contours and resynthesis resulting in speech that sounded as much like natural speech as possible. Sentences were vocoded and resynthesized using either a monotone contour or the original contour. Listeners' reaction times to monotone short, simple sentences were slower by 48 ms than their reaction times to the same sentences with normal fundamental frequency contours. Reaction times to longer sentences with complex syntactic structures will also be presented. The results suggest that an adequate model of speech perception and comprehension must incorporate intonation. The contributions of segmental effects, terminal fall, stressed syllables, and declination are considered. [Work supported by NIH and the Sloan Foundation.]
Exploiting lawful variability in the signal: The TRACE model of speech perception
Authors: Elman Jeffrey L. , McClelland James L.
Published: January 2006

We describe a model of speech perception in which lawful variability in the speech signal is treated as a source of additional information, rather than as noise. Excitatory and inhibitory interactions among nodes for phonetic features, phonemes, and words are used to account for aspects of coarticulation, as well as the interaction of bottom-up and top-down processes in perception of speech. Two results from a working computer simulation of this model are presented. First, we show how the simulation is able to process real (digitized) speech and retune the detection of features and phonemes in accord with the context. Second, we demonstrate how perceptual behavior which appears to be guided by rules can be induced without any explicit rules in the system. [Work supported by the Office of Naval Research.]
Neural response patterns to speech sounds—A model
Authors: Divenyi Pierre L. , Shannon Robert V. , Saunders Stephen R.
Published: January 2006

We propose a four-stage model to represent auditory response magnitude over time and across frequency channels. The first stage performs spectral estimation by computing power at each of the output frequency channels. Frequency is scaled in basilar membrane distance and the input is passed through a window having a duration inversely proportional to the frequency. The next stage has been described earlier [R. V. Shannon, J. Acoust. Soc. Am. Suppl. 1 65, S56 (1979)]; it portrays frequency analysis in the cochlea. This stage includes mechanisms of cochlear filtering (by means of two filter banks, one having sharp and the other having broad filters), nonlinear compression of the input power, and lateral suppression. The third stage models temporal adaptation in the auditory nerve. The final stage is a temporal integrator. Speech sounds analyzed by the model acquire several interesting characteristics: (i) The dynamic range of the input is greatly reduced (<15 dB), (ii) bandpass information (e.g., the one in formants, fricatives, etc.) is represented as a spectral edge at the low side of the bandpass region, (iii) bursts (especially high-frequency plosives) acquire temporal sharpness, (iv) individual glottal pulses are clearly visible only at high frequencies. [Work supported by Institut National de la Recherche Scientifique, the Veterans Administration, and grants by N.I.H.]