bluuebunny/crossref_metadata_2025 huggingface dataset:
Information conveyed by vowels: a negative finding
Authors: Dechovitz David R.
Published: October 2005

An early study with synthetic speech suggested that vowel identification includes a normalization stage, such that the listener calibrates his perceptual apparatus for each talker's vowel space [Peter Ladefoged and D. E. Broadbent, J. Acoust. Soc. Am. 29, 1 (1957)]. In the present study, no evidence for such a perceptual mechanism was obtained using natural speech. Each of a set of b-vowel-t test; words, spoken rapidly within a sentence carrier by an adult male was presented for recognition within the carrier in which It was uttered, appropriately embedded within an identical carrier produced by a second adult male with substantially different vocal tract dimensions, and excised from sentence context. The two talkers achieved the same pitch levels and speaking rate, with the result that mixed-talker sentences were perceived as if uttered by one talker. Errors in recognition were typically found only for isolated test words. Preliminary data from a replication of this design with more widely divergent vocal tracts (i.e., adult male and nine-year-old male) are similar. Apparently, some factors beyond the syllable shape the acoustic specification of vowels, though not in the sense in which normalization is traditionally defined.
Decay of the acoustic reflex during steady-state and intermittent noise exposures
Authors: Hétu R. , Careau P. U.
Published: October 2005

Acoustic-reflex activity was continuously monitored by measuring change in the acoustic impedance at the eardrum for seven normal-hearing young adults under three temporal patterns of exposure to a broadband noise: one steady-state condition of 16 min duration at 105 dBA and two intermittent conditions of 32 min total duration with sound levels alternating between 105 dBA and quiet every 1 or 4 min, depending upon the condition. It was found that after 16 min of actual noise exposure, acoustic-reflex response decreased to 40% of initial magnitude under the steady-state and the 4-min on—off conditions. Under both intermittent conditions, progressive decrease of on-response following onset of successive noise bursts showed that quiet periods allowed only partial restoration of initial reflex excitability. Under the 4-min on–off condition, it was observed that the contractile strength of the middle ear muscles recovered to the level observed for equivalent exposure times under the 1-min on—off condition; however, during the third minute of the, 4-min bursts, it decreased to the level observed under the steady-state noise condition for equivalent cumulative exposure time.
Introduction to the special session on construction noise
Authors: Brittain F. H.
Published: October 2005

As an introduction to the session on construction noise at University Park, PA, the state of the art in construction equipment and site noise prediction, measurement and control will be reviewed. Typical construction equipment and site noise levels will be indicated. Standard procedures to measure equipment noise levels, particuarly SAE J88 and J88a, will be reviewed. Construction-site noise levels predicted by adding worst-case equipment noise levels, result in conservative site levels, since not all equipment operate simultaneously. Alternative techniques to predict either maximum likely, equivalent (Leq) or statistical (Ln) noise levels instead of maximum noise levels will be described. The existing state of the art in construction noise control will be illustrated in terms of noise control for portable air compressors and pile drivers.
Noise control for crawler and wheel tractors
Authors: Mirabelli R. E. , Gray L.
Published: October 2005

Noise-control techniques applicable to quieting crawler and wheel tractors ranging from 20 to 500 hp were surveyed. Two levels of technology were considered: (1) retrofit technology which did not require major machine modifications and (2) machine redesign. Noise reductions achievable where shown to average 2–6 dBA using retrofit techniques and 6–9 dBA utilizing machine redesign with the larger noise reductions being achieved on lower horsepower machines. Problems associated with machine performance, maintenance, and safety arising from noise-control applications, were investigated and found to be limiting factors in the noise reduction achievable through retrofit techniques. [Work supported in part by EPA.]
Measurements of the varying noise level from power-plant construction activities
Authors: Teplitzky A. M. , Barnes J. D. , Wood E. W.
Published: October 2005

Construction noise prediction procedures should account for the varying noise level output of numerous on-site machines in order to estimate the energy average sound level from large sites. Nearfield and farfield noise-level measurements obtained at a number of power-plant construction sites are reported, along with methods to quantify the sound levels from typical operating machines and from entire power-plant construction sites. These data and methods provide useful insights to predict and abate noise emissions from construction sites. [Work supported by Empire State Electric Energy Research Corporation.]
Some aspects of the ground vibration problem from construction equipment
Authors: Gutowski T. G. , Wittig L. E. , Dym C. L.
Published: October 2005

Groundborne vibration from construction equipment can be annoying to neighbors. Three common claims are (a) vibration is perceptible; (2) vibration causes building damage; and (3) vibration induces soil settlement with possible building damage. From a predictive point of view, this problem may be approached by the source-path-receiver method. Source and path characteristics should be determined from on-site measurements when possible. Source or geological characteristics may, unexpectedly, cause horizontal motion to dominate; therefore, triaxial measurements are advised. Instrumentation will depend upon criteria. Guidelines for receiver criteria are available in the literature; however, many aspects of the problem are not yet understood. This paper will discuss the results of a recent study to predict and assess vibration related to the construction of a proposed interstate highway in Baltimore City. Vibration from pile driving, pile augering, slurry wall construction, and other construction equipment will be considered in the context of the approach outlined above.
Computer analysis of health and welfare impact of construction-site noise
Authors: Brown X. , Yue K. , Goldstein Jeffrey
Published: October 2005

As may be expected, the noise impact of construction-site activity varies widely with the type and phase of construction as well as with topographic and demographic factors. In order to evaluate the public health and welfare impact of construction-site noise, a large number of construction activity scenarios must be considered. The assessment method discussed in this paper involves the computation, on a national basis, of the total population impacted by construction-site noise in terms of the number of people exposed and the severity of impact. A computer model to estimate the population impacted by construction site noise was successfully programmed for the IBM/370 computer. The computer model is based on the EPA construction-site noise and population-impact method. The model considers 30 types of construction equipment, four types of construction activity, five construction phases, and five population-density land uses. The computer program computes an Equivalent Noise Index (ENI) and also tabulates the population exposed to construction-site noise levels above any specified day-night average sound level. The effectiveness and versatility of the program enables the user to determine construction-site noise impact, taking into consideration a large number of variables which predominantly affect the extent and severity of that impact. Examples of computer model application will be presented.
Wide-bandwidth array considerations with loudspeaker systems
Authors: Abbagnaro Louis A.
Published: October 2005

Direct radiator and horn loudspeakers present many different array problems. Some of these, such as the change in the directional radiation patterns as a function of size and frequency and the development of columar loudspeaker designs have received considerable attention in the literature. Others, however, such as the arraylike interaction of individual drivers in a single loudspeaker and the performance of large arrays of wide-bandwidth loudspeaker systems have been given considerably less treatment. This paper will review these topics using array analysis considerations.
GATS—problems and solutions
Authors: Mitchell O. M. M. , Stockbridge C. D.
Published: October 2005

A group audio teleconferencing system (GATS) is an audio communications link between groups of people in different locations. Its operation depends in a complex manner on the operation of the system components: room acoustic environments, terminal equipment, transmission facilities, and conference bridges. The main problems encountered are room reverberation, room and circuit noise, chopping of speech by voice switching, and loss contrast (differences in speech levels from various rooms). Solutions to problems of reverberation will be discussed in accompaning papers (Stockbridge et al. and Curtis et al.). This paper discusses solutions to the problem of loss contrast, in particular, use of standard level sound source in alignment and testing of GATS. References will be made to a working example of GATS—the General Service Administration Teleconference System.
To honor Edison
Authors: Levitt H. , Stromberg H.
Published: October 2005

The phonograph was invented by Thomas Alva Edison 100 years ago. In Edison's view the phonograph was a tool for use in business or research and not as a source of entertainment. One of the earliest applications of the phonograph was in scientific research where it was used to study the acoustic characteristics of vowels and other speech sounds. The phonograph soon replaced the phonoautograf as the instrument of choice in recording acoustic waveforms. The research literature of that period contain several illustrations of waveforms obtained with either the phonograph, phonoautograf or related instruments, including several waveforms that were recorded graphically prior to the invention of the phonograph. As a tribute to Edison, we have reproduced several of these earliest known sound recordings using conventional digital signal-processing techniques.
Application of interactive computer graphics to research is acoustics
Authors: Stocker F. R.
Published: October 2005

A review of the developmental efforts in the areas of interactive graphics hardware and software support systems will be presented with the aid of a series of movie segments and slides extracted from various research related films created using primarily graphics systems made available by the Computation Center. Interactive research support systems will be considered from three viewpoints. First, the viewpoint of the people conducting the research. Second, the viewpoint of the researchers who do the detailed computer implimentations. Third, the viewpoint of experienced graphics consultants. In particular the methods of developing realistic objectives as they relate to the three areas mentioned above will be considered. Results based on the methods considered will be covered during several other presentations in this conference.
SPOTLIGHT: a signal-processing system for passive SONAR
Authors: Rahe G. A. , Robbins C. B.
Published: October 2005

SPOTLIGHT is an integrated signal-processing display system which employs a time-amplitude-frequency orthogonal display and a hidden line-removal technique to reduce clutter and create the appearance of a relief map. The signal processor employs an ideal box-car integrator and overlapped transform methods to allow significant signal-processing gains from increase integration time. This technique retains the ability to track dynamic changes in signal frequencies which would otherwise be lost during long integration intervals. Identification is provided by amplitude correlation of signals with specific target characteristic relationships. A sliding linear-amplitude scale provides the display with a dynamic range matched to the signal processor. Cursors which increase the intensity of a few resolution bins may be swept through the selected frequency groups under operator control. The frequency location of the cursors in each group is displayed to the operator in a continuous alphanumeric read out. These cursors may be moved independently or according to the relationships of the groups like a SPOTLIGHT shining on a topological surface.
Raster driven color CRT displays
Authors: MCleary L. E.
Published: October 2005

Three acoustics research projects which have successfully used continuous tone color CRT display techniques will be discussed. (1) A 16-mm movie will be show which displays the vibrational mode shape of a free-flooded, piezoelectric cylinder transducer, as well as the nearfield pressure patterns which change as a function of time. This movie was produced for NUC by Dr. Henry Christiansen of Brigham Young University, using equipment at the University of Utah. Data was provided by NUC using mathematical models based on finite-element methods. (2) Slides will be shown of additional three-dimensional displays generated at NUC using a computer program, MOVIE-NUC, which was adapted by Christiansen to run on NUC equipment. One such example is for an ambiguity surface displayed in three dimensions using color contours to enhance the intensity component. (3) An additional application to be shown will be slides of two-dimensional displays of large ocean areas. Pacific and Atlantic Ocean bathemetry data will be displayed using color contours. Other parameters to be displayed include the amount if intrusion of the ocean bottom into the sound channel and shipping density.
Perceptual equivalence of cues for the fricative-affricate contrast
Authors: Raphael Lawrence J. , Dorman M. F.
Published: October 2005

The present study investigated perceptual cues for the word-final fricative-affricate contrast, e.g., as in dish-ditch. When the closure interval between vowel and fricative in dish is increased, listeners perceive ditch. The duration of closure interval necessary for the perception of the affricative varies as a function of both friction rise time and friction duration. Thus, duration of closure interval, duration of friction, and friction rise time can be traded off in the perception of an affricate. The phonetic equivalence of these acoustically dissimilar cues can be readily accounted for on the view that they are the distributed acoustic consequences of the gestures that distinguish dish from ditch. To suggest this, of course, is to suggest a link in speech between perception and production. [Work supported by NICHD.]
On the dissociation of spectral and temporal cues for stop consonant manner
Authors: Summerfield Quentin , Bailey Peter
Published: October 2005

Using parallel formant synthesis we are investigating the conditions under which the sequence of segments friction + silence + vocalic gives rise to the percept of an interpolated stop consonant. When the vocalic segment is a two-formant steady-state vowel, the probability of a stop percept increases as (1) the duration of silence is lengthened, and (2) the frequency of F1 is lowered, showing perceptual sensitivity to spectral and temporal correlates of stop production and demonstrating that neither is sufficient for the perception of a stop in this context. Bilabials are heard when F2 is below about 1500 Hz, e.g., [spd], velars when it is above 1500 Hz, e.g., [ski]. Alveolars are not heard unless formants higher than F2 are included suggesting that the information for stop place bears a closer relation to that associated with stop releases than to formant transitions here. The duration of silence required to cue an interpolated stop—the [sv-scv] boundary—decreases as the frequency of F2 is raised, possibly in reflection of the shorter closure durations in natural productions of [ski] versus [spu]. With a CV syllable as the covalic segment, the boundary decreases with increases in the spectral extent of an F1 transition whose onset frequency is fixed, showing an influence of the transition, per se, and offering the possibility of quantifying the potency for cueing stop manner of different rates, durations and extents of F1 transition.
Effects of transition length on identification and discrimination along a place continuum
Authors: Mandler R. , Dechovitz D.
Published: October 2005

A model of the decision process in discrimination tasks attributes categorical perception along the stop continuum to the transience of the acoustic signal serving as the basis for phonetic divisions [H. Fujisaki and T. Kawashima, Annual Report of the Engineering Research Institute (1970)]. Two continua of fourteen voiced stop consonants ranging from /ba/ through /ga/ were produced for comparison. In one, transition duration of all three formants was fixed at 30 msec, while in the other, F2 and F3 transitions were lengthened to 135 msec, with other parameters left unaltered. Forced-choice identification and same-different discrimination tests were constructed for each set. Responses given by 20 University of Connecticut undergraduates were nearly identical for the two stimulus sets. These results indicate that transience is not the basis for categorical perception of stop consonants.
Perceptual correlates of vowel nasalization
Authors: Wright J. T.
Published: October 2005

The perceptual correlates of vowel nasalization were investigated by means of the multidimensional scaling of individual differences (INDSCAL). Steady-state vowels corresponding to [i, e, ε, æ, a, o, U, u] and their nasalized counterparts were matched for tongue configuration across the oral and nasal conditions using optical palatography. Sixteen listeners heard all possible pairings of the stimuli and made similarity judgements on an interval scale. INDSCAL generated a unique analysis at four dimensions, the most salient of which corresponded to the articulatory parameters high/low, front/back, and nasal/non-nasal. The fourth dimension correlated with differences in F0 between the nonmatched vowels (corresponding oral and nasalized vowels had F0 values that were within 1 Hz). Along the height dimension, high- and midnasalized vowels were consistently lower than their oral counterparts while the low-nasalized vowels were higher. The results provide evidence that listeners use a dimension corresponding to perceived degree of nasality in making judgements of similarity in the vowel space. They further suggest that perturbations in the first-formant region due to nasalization are perceived as changes in vowel height. [Supported by NSF.]
Closure hiatus: cue to voicing, manner and place of consonant occlusion
Authors: Lisker L.
Published: October 2005

Delayed onset of laryngeal vibration following release of an initial stop by about 35 ± 15 msec generates acoustic features eliciting p,t,k responses from speakers of English. These features, by a common misnomer, are referred to as cues to stop voicelessness; in fact, they are cues to voiceless-stop aspiration. Medially before unstressed vowels English has voiceless stops that are not aspirated, and these lack some of the features of initial /p,t,k/. An important cue to medial /p,k/ before unstressed vowel is an interruption of glottal pulsing during closure, provided this interruption exceeds a certain duration. In experiments replicating and extending earlier studies a number of naturally produced and synthesized polysyllables were varied in respect to their closure intervals. In part results replicated earlier findings, but not unambiguously. It appeared that (1) there were significant individual differences in response to stimuli with edited closure intervals; (2) stimuli derived from different tokens of the same phonetic types elicited different responses, and (3) the apical flap [ɾ] response to very short closure intervals could not be entirely explained by a simple motor theory interpretation.
Onset spectra as cues for consonantal place of articulation
Authors: Stevens Kenneth N. , Blumstein Sheila E.
Published: October 2005

The aim of this paper is to review the theoretical and experimental support for the view that invariant cues for place of articulation for stop consonants reside in the gross shape of the short-term spectrum at the consonantal release. This gross spectral shape is determined both by the burst of acoustic energy at release and by the frequencies of the second and higher vocal-tract resonances immediately following the release, and is largely independent of the following vowel. Measurements of onset spectra from real speech show distinctively different gross shapes for different places of articulation: diffuse spectra for labials and alveolars and spectra with relatively narrow energy concentrations for velars. These spectral shapes are in accord with predictions of acoustical theory. Consonant identification tests were conducted in which the shapes of the onset spectra were systematically manipulated to produce various stimulus series. Results are consistent with theoretical predictions based on production and further indicate the range of attributes of the gross spectrum shape associated with the various phonetic categories. [Work supported in part by NINCDS.]
Effect of allophonic variation upon phonetic feature recognition in dichotic backward masking
Authors: Alfonso Peter J. , Daniloff Raymond G.
Published: October 2005

Synthetic stimuli (generated at Haskins Laboratories) were used to elicit monaural identification and discrimination data for two seven-step place continua /ba-da; pa-ta/, and two seven-step voicing continua /ba-pa; da-ta/. Five subjects who demonstrated categorical perception participated in three dichotic experiments. Using the same stimuli, dichotic experimental tapes with stimulus onset asynchonies ranging from 0 to 200 msec were made. Subjects were instructed to identify the stimulus presented to the right ear, which was always the leading syllable and a canonical form (step one or seven of the four continua). The first experiment employed canonical forms as the masker. Experiment two used stimuli from steps two-six from the voicing continua whereas experiment three used corresponding stimuli from the place continua. The target intelligibility data from experiments two and three were compared with data collected with data collected from experiment one and the monaural experiment. The influence of acoustic versus phonetic competition in the dichotic backward masking paradigm is discussed. [Work supported in part by NIH and Sigma XI.]
Left handers outperform right handers on a pitch memory task
Authors: Deutsch Diana
Published: October 2005

Subjects were presented with a test tone, followed by six interpolated tones and then by a second test tone; and they judged whether the test tones were the same or different in pitch. The test tones were either identical or they differed by a semitone. The experiment employed 76 right handers and 53 left handers, balanced for sex and musical experience. The left-handed group was found to display a significantly higher overall performance level, and also a significantly higher variance. It appears that left handers tend to be less susceptible to the disruptive effects of interpolated tones, at least when these can be ignored.
Cues used in recognition memory for tones
Authors: Dewar K. M.
Published: October 2005

Previous research [K. M. Dewar, L. L. Cuddy, and D. J. K. Mewhort, “Human Learning and Memory,” J. Exp. Psych. 3, 60–67 (1977)] has shown that the pitch of a single tone from a tone sequence was recognized more accurately when recognition was tested within the context of the original sequence that when it was tested in isolation. Relational factors, e.g., pitch contour and interval coding, may operate to help overcome the basic limitations on processing the pitch of isolated tones. The role of pitch versus temporal context and the effect of contour changes were examined. Musically trained and untrained listeners were presented with partial-context and full-context conditions (where they were given some information about the pitches surrounding the test pitch) along with a temporal-context condition (where they were given information only about the temporal position of the test tone). Random seven-tone sequences generated by a PDP-11 computer were used, each tone being presented for one-half second. For all listeners, performance was better in the partial and full-context conditions than in the temporal-context condition. Listeners made significantly more errors when the contour (the pattern of ups and downs) of the test sequence remained the same as the standard that when it changed, regardless of the distance between the correct and incorrect pitches. Listeners did make fewer errors the father apart the pitches. [Work supported by the Canadian National Research Council.]
Remote audiometric testing via telephone: the design of a digitally controlled audiometer
Authors: Yonovitz A. , Mitchell C. W. , Lozar J.
Published: October 2005

The acquisition of pure tone and speech audiometric data from a remote location would be especially useful in schools, industrial applications, military usage, physicians' practices, and hospital-medical-center environments. Data transmission using standard ASCII encoding (with RS-232c interface) provide an efficient means of controlling the acoustic parameters in audiometric testing. Essentially, in a digitally controlled audiometer, the devices receive and transmit control commands at a 300 baud rate readily compatible with available computer hardward interfaces. Unique design concepts including simultaneous use of the acoustic coupler modes for speech and data transmission are discussed. Using FSK coding techniques the ordinary telephone system may be employed to remotely relate audiological diagnostic information between two locations.
Phase discrimination and level effects
Authors: Nelson D. A.
Published: October 2005

Phase shifts in three-component waveforms (commonly referred to as AM and QFM signals) can be discriminated when frequency separations between components are not too large. The limits of this auditory ability offer yet another indication of a critical bandwidth for frequency resolution. To explore this phenomenon further, phase-discrimination functions (percent-correct waveform discrimination as a function of bandwidth) were obtained from normal-hearing listeners. A forced-choice procedure was used to obtain phase discrimination functions for several combinations of (1) the overall intensity of the three-tone complexes, and (2) the relative intensities of the individual components in the three-tone complexes. The results indicate this bandwidth measure to be highly dependent on both intensity parameters. Discussion of relevant explanations centers around two hypotheses: envelope detection and the internal spectrum.
Five experiments on frequency-modulation width perception
Authors: Hartmann W. M.
Published: October 2005

In the FM (vibrato) experiment subjects choose which of two frequency-modulated tones has the wider pitch excursion. One of the two tones is modulated with a sine wave, the other is modulated with a triangular wave. New experimental results are reported on the effect of different tone center frequencies, of subject training, of blocking of stimuli by modulation rate, and by modulation index. FM experiments with harmonics 3, 4, 5, and 6 of a missing fundamental (f1 = 200 Hz) are compared with experiments for sine-wave tones, f1 = 200 and f1 = 800 Hz. The perception of pitch excursion for the complex tones seems to be similar to that for sine waves, but the complex-tone experiments result in smaller variations in performance. The experimental results appear to require that at least three mechanisms can be involved in vibrato width perception. [Work supported by the NSF.]
Infrapitch periodicity: perception of missing fundamental and component periodicities for mixed iterated random waveforms below 20 Hz
Authors: Warren Richard M. , Bashford James
Published: October 2005

Periodicities lacking pitch are perceived effortlessly for uninterrupted repeated sections of Gaussian noise (URSGN) from 1 to 19 Hz [Guttman and Julesz, J. Acoust. Soc. Am. 35, 610 (1963)]. We explored interactions of infrapitch periodicities by mixing two independent URSGN's having different frequencies within the four-octave range from 1 to 16 Hz. Slight mistuning from unison prevented periodicity detection. If the URSGN frequencies differed by an octave (f and 2f), both periodicites were detected with the lower frequency seeming perceptually dominant. For URSGN frequency pairs of 2f and 3f, or 3f and 4f (f equal to or greater than 1 Hz) (1) The missing fundamental [f] was the perceptually dominant periodicity; (2) The lower harmonic of the pair was detected fairly readily; and (3) The upper harmonic was heard with greater difficulty. Slight mistuning of component URSGN's from integral ratios destroyed perception of any periodicity. By using infrapitch URSGN's, detection of neural pattern periodicity can be studied without the concurrent cochlear place cues to repetition frequency associated with the pitch range. [Research supported by NSF and NIH.]
On the bases of similarity of musical intervals: a chronometric analysis
Authors: Balzano Gerald J.
Published: October 2005

Musician subjects were timed as they responded SAME or DIFFERENT on the basis of whether a visually presented musical-interval name (question) correctly identified an auditorily presented musical interval (stimulus). On trials where the question-stimulus pair did not match, the time required to respond DIFFERENT was used as an index of the perceived similarity of that pair of intervals. Multidimensional scaling of the matrix of DIFFERENT reaction times yielded a two-dimensional configuration with the intervals in a nearly circular arrangement, corresponding to the musical “dimension” of tone chroma [R.N. Shepard, J. Acoust. Soc. Am. 36, 2346–2353 (1964)]. A scaling analysis of the error proportions yielded essentially the same configuration. By a more fine-grained analysis of the DIFFERENT reaction times it was revealed that among interval pairs differing by one semitone, intervals that shared the same scale step, such as major 2nd and minor 2nd, required over 250 msec longer to respond DIFFERENT to and led to significantly more errors than intervals that did not share this property (e.g., major 2nd, minor 3rd). These results contrast sharply with the view [R. Plomp, W.A. Wagenaar, and A.M. Mimpen, Acustica 29, 101–109 (1973)] that differences in width constitute the sole basis for the perceived similarity of musical intervals.
Graphic display of sound fields in a rectangular enclosure
Authors: Ochs J. B.
Published: October 2005

The spatial variations of the low-frequency sound fields in a rectangular enclosure at and between the first few axial, tangential and oblique modes are displayed with the aid of an Interactive Graphics Terminal Environment. By employing a gradation in color corresponding to the theoretically derived sound pressure level at several hundred points equally spaced in the enclosure, the movie dramatically illustrates the three dimensional mode shapes that typically occur in rectangular reverberation chambers with high-impedance walls.
Using animated modal computer graphics for vehicle sound and vibration problem solving
Authors: Davis C. W.
Published: October 2005

A new technique for using animated modal analysis for vehicle dynamometer sound and vibration diagnostic work has proven very effective at Ford Motor's Engineering Center in Dearborn. These techniques allow visual observation of vehicles structure (amplified and slowed down) while it is exhibiting a problem, i.e., boom, shake, moan, etc. A video-tape showing how the data is obtained and a stick-figure animation of a boom problem will be shown. The graphical presentation of this data provided a solution in a few days as compared to several weeks using conventional methods.
Computer-based acousto-optic image processing
Authors: Dardy H. D. , Bucaro J. A.
Published: October 2005

The ability to quantify acousto-optic images generated through conventional schlieren, Bragg and holographic techniques has been hampered in part by the massive amount of data contained within a single image frame. The rush of technology has produced state of the art advances in small computer design and fabrication, allowing for simple video image systems to couple directly for applications to real problems. We will discuss the data requirements of such a system with emphasis on the digitization, storage, and computer linearization processes necessary to reconstruct an accurate quantitative acoustic image; a pseudocolor technique to allow easier presentation of an image's resolution and dynamic range will also be considered.
Results of research conducted in acoustics considered from the graphics viewpoint
Authors: Stocker F. R.
Published: October 2005

Various stages in the development of computer models to support research in acoustics will be considered. Emphasis will be placed on the use of interactive computer graphics to provide increased comprehension and thus new insights into the nature of the experimental data. Specifically, problems of image enhancement will be discussed as they relate to visual perception of multidimensional models where the number of dimensions necessary to achieve new insights has been extended beyond three. A film summarizing some of the results achieved to date will be shown.
Fourier spectral analysis using Walsh functions
Authors: Cavanagh E.
Published: October 2005

Digital electronics allows for the easy generation of Walsh functions, which are a set of orthogonal functions Periodic functions can be expanded into Walsh series by finding the expansion coefficient in the normal manner of multiplying the function and integrating over one period. From these coefficients, the Fourier-expansion coefficient can be calculated. For sinusoidal waves, in-phase and quadrature Fourier components can be ascertained by two Walsh-function coefficients.
Concepts in nonlinear acoustics: II. Implementations and Applications
Authors: Tighe Frank
Published: October 2005

The nonlinear (or parametric) array is of interest in acoustics primarily due to its superdirectivity; that is, its narrow beamwidth and extremely low side-lobe levels. The superdirectivity has an applicability in situations where reverberation or multipaths limit operation or when covertness is important. In this paper, the properties of a parametric beam are discussed and the importance of these properties to certain underwater operations is illustrated; a hypothetical system is designed to generate a parametric beam and is compared to two linear systems generating similar beams; and a partial list of present parametric sources is presented.
Community noise measurement systems
Authors: Blomquist Donald S.
Published: October 2005

The National Bureau of Standards has developed a measurement system for use by Department of Housing and Urban Development (HUD) field personnel. This system measures community noise in conformance with HUD Policy Circular 1390.2. Seventeen of these systems, built to NBS-designed specifications by a private contractor, have been used in the ten HUD regional offices since July 1975. The system is designed to provide unattended, continuous operation for a 24-h period and has been used throughout the United States, including Alaska. The design problems, failures, and errors associated with utilizing a continuous noise measurement system are discussed.
New spatial sampling methodology for community noise
Authors: Miller R. K.
Published: October 2005

Prior to the performance of noise measurements, expected sound levels of a community or city are first predicted. These expected sound levels are utilized to develop sampling zones. Specific measurement locations are then randomly selected within each zone. The advantage of the methodology is that the noise zones are more homogeneous than those which would be associated with other survey methodologies (such as the 1-mile-square grid method). The results provide a higher resolution for noise maps than those associated with a square grid survey, and achieve a lower standard deviation associated with spatial acoustical variations. The lower standard-deviation results in considerably fewer sampling locations being required to achieve a predetermined survey accuracy. This, of course, results in a significant cost savings where surveys of large cities are considered. The methodology has been applied in surveys of the cities of Chattanooga, Tennessee and Torrance, California. Spatial standard deviations as low as 2.1 dB were achieved. A review of the results of 27 other major noise surveys indicates that standard deviations typically ranged from 3.5 to 10 dB. [Work sponsored by The City of Chattanooga, U. S. Environmental Protection Agency, and Wyle Laboratories.]
Novel approach to community noise monitoring
Authors: Alexander Martin , Kessler Frederick M.
Published: October 2005

Numerous small cities and towns in New Jersey have been preparing Natural Resource Inventories (NRI). These NRI's document the present environmental, sociological, historical, and other facets, of the communities' quality of life. One parameter in the NRI is sound quality. A comprehensive survey to document sound levels in residential, commercial, industrial, and other land-use areas is necessary. The cost to accomplish these surveys using sophisticated equipment and trained personnel can be quite prohibitive. This is especially true if the community is large. In three New Jersey communities an alternate approach was used. Through a series of public meetings, community residents were made aware of the NRI and particularly the sound quality aspects. Volunteers were trained in the use of sound level meters and a simple measurement procedure similar to the SAE method for measuring construction site noise. The data resulting from measurement made by the volunteers allowed a mapping of sound levels in the community. The mapping provides guidance to planners and may aid in the development of a national community noise ordinance sensitive to the existing sound quality of the township. Typical results are presented for one township, in New Jersey. [Work supported by EPA.]
Design of an attitudinal questionnaire for use in local noise program monitoring and assessment
Authors: Bush S. A. , Case J. D. , Shampan J.
Published: October 2005

To provide local government officials with a comprehensive attitudinal questionnaire which will aid in local noise program monitoring and assessment, past applications of over 30 noise-related attitudinal surveys were evaluated. Follow-up discussions with nine local agencies which have conducted such studies provided a unique perspective for analyzing those issues which are of the utmost importance to local government officials involved in noise management programs. A computer-based questionnaire information system facilitated the analysis of previously used questions. The questionnaire developed in this study should facilitate comparison of results among communities due to the use of a standardized annoyance descriptor and response scale for assessing community noise-related attitudes and responses. The questionnaire was designed to be brief and straightforward in gauging neighborhood environmental problems, the effects of noise, public awareness, perception of noise abatement feasibility, identification of local government initiatives which are needed and willingness-to-pay for specific reductions in overall noise level. [Work supported by EPA.]
Low-frequency directional ring hydrophone
Authors: Zalesak Joseph F.
Published: October 2005

In its simplest form, a low-frequency directional ring hydrophone (LFDRH) is a free-flooded circumferentially polarized piezoceramic tube. At some very low frequency an LFDRH has a cos2θ directivity pattern with a maximum along the symmetry axis. For example a 5 cm high, 5 cm outerdiameter, 0.4 cm thick circumferentially polarized ring exhibits this directivity at about 1675 Hz. Since a cos2θ pattern is symmetric, the hydrophone is not acceleration sensitive. The bandwidth of operation is fairly narrow (about 12-octave) but can be extended by using a number of rings and connecting their outputs to a crossover network. An alternate configuration for the LFDRH is a combination of an omnidirectional hydrophone and a free-flooded piezoceramic tube of arbitrary polarization. By properly varying the relative weighting with frequency, a broadband device can be constructed and the frequency of operation can be extended below that of a circumferentially polarized ring of the same size. The outputs of three LFDRH's can be combined to yield a cos2θ pattern which may be rotated in any direction in a plane. Also, the outputs of two hydrophones can be processed to yield target bearing. [Work supported by Naval Electronics Systems Command.]
Low-frequency spherical-shell projectors
Authors: Lee J. B.
Published: October 2005

The spherical-shell projector comprises a piezoelectric ceramic ring driving two concave spherical shell segments in flexure. One model resonant at 600 Hz in water weighs 15 kg and delivers a souce level of 201.5 dB re 1 μPa at 1 m. Its mechanical Q is 5 and efficiency 80% at resonance. An axially-symmetric finite element model is being used to study the performance of spherical-shell projectors and generally good agreement is achieved between the calculated and experimental results.
Mathematical model for underwater electroacoustic transducer elements
Authors: Skiba E. L. , Allen R. B. , Charlwood R. G.
Published: October 2005

A dynamic finite element model was developed to analyze the vibrations and acoustic radiation of a single axisymmetric electroacoustic transducer and its attached mechanical amplifying structure and waterproofing material. Element types are 2-D isotropic solid, axially radially poled and tangentially poled piezoelectric solids, acoustic fluid, membrane, fluid-solid link, spherical Helmholtz radiating boundary and silvered surface. Undamped resonances and antiresonances in air are extracted by the inverse iteration method with eigenvalue shifting. Undamped low-frequency capacitance is found by harmonic voltage driving of the transducer with subsequent calculation of the charge on a silvered surface. In water, the damped (material damping and acoustic radiation) complex response is determined for similar voltage driving and the complex impedance and far-field directional response are calculated. The model is programmed with an overlay structure and makes extensive use of mass disc storage enabling the solution of large problems using a small core allotment. Extensive testing has been successfully carried out against experimental data. [Model developed under contract to the Department of National Defence, Canada.]
Active acceleration canceling for directional hydrophones
Authors: Schumann J.
Published: October 2005

Directional transducers which are suspended from surface floats or moorings are subjects to suspension cable strumming and flow induced vibration. These inputs can mask the desired acoustical signals at low frequencies. A dynamic acceleration canceling system which senses case vibration and removes its response from the output of the acoustical sensor has been developed and tested. A reduction of vibration response by 14 dB has been measured in the laboratory with an additional acoustic sensitivity increase of 1 to 2 dB. The system comprises a simple piezoelectric accelerometer and associated electronics in addition to the usual hardware associated with the acoustic sensor. It can be used with any direct acting acoustic transducer scheme but not with geophone-type hydrophones.
Design considerations for electroacoustic projector systems
Authors: Young J. W.
Published: October 2005

In the development of a high power electro-acoustic projector system, the goal of system optimization is frequently obscured by the details of amplifier and transducer design. The typical design procedure centers on transducer source per volt (SPV), source per ampere (SPA), and efficiency. It is the purpose of this paper to show that an optimum system can be achieved more easily by emphasizing different transducer and system parameters. The following assertions are made: (1) The fundamental measure of transducer performance for narrowband applications is the source per watt (SPW). (2) For broadband applications, the source per volt-ampere (SPVA) is a limiting parameter due to the difficulty of tuning out the transducer reactance over a wide frequency range. (3) In addition to transducer efficiency, two definitions of system efficiency are significant. These are the efficiencies with respect to either available power or total dissipated power. These quantities cannot be simultaneously optimized, but rational trade-offs can be achieved. In this paper, the above mentioned quantities are defined in terms of more traditional parameters, and their interrelationships are developed. It is shown how this approach can aid in achieving an optimum system design. Through this procedure, the traditional difficulties of interfacing transducer and electronic systems can be reduced.
Phase-locking in AVCN units of cat
Authors: Bourk T. R.
Published: October 2005

Single unit activity in the AVCN of dial anesthetized cats was recorded with platinum-tipped indium-filled microelectrodes. Units were categorized on the basis of spike waveforms and responses to tonal stimuli. Synchronization index (vector strength) was computed from period histograms of the responses to continuous tones. The dependence of synchronization on stimulus level was determined for different frequencies and a maximum value (Smax) assigned to each level series that appeared to saturate or attain a maximum. A plot of Smax versus the frequency of the tone shows two groups of units. One group, with Smax values similar to those found for auditory-nerve fibers, represents the “primarylike” and “on” units. The other group, with lower Smax values, are “chopper” units. Below 800 Hz the two groups are difficult to distinguish on the basis of Smax values. Thus the earlier observations that the responses of some units are better phase-locked than others is confirmed and shown to be related to standard unit types as defined by other response properties. [Work supported in part by NIH.]
Response patterns of neurons in the lagenar branch of the goldfish auditory nerve
Authors: Fay Richard R. , Olsho Lynne
Published: October 2005

The response of single fibers of the goldfish lagenar nerve were recorded extracellularly in response to tonal stimuli generated by a loudspeaker. Measures were made of both the average impulse rate and the degree of phase locking at a number of different stimulus frequencies and sound pressure levels. Phase locking was determined to be a more sensitive and reliable measure of sound pressure sensitivity than impulse rate. Unit tuning curves constructed using phase-locking criteria showed low-pass characteristics above 150 Hz. Wide variability was observed in sensitivity, bandwidth, spontaneous activity and adaptation. Lagenar fibers overlap in sensitivity with type II saccular neurons described by Fay [J. Acoust. Soc. Am. 60, S80 (A) (1976)]. The discharge patterns of lagenar and saccular neurons were analyzed in response to direct vibration of the head and were found to have quite similar directional sensitivities. The results are discussed in terms of the information available to the fish for auditory localization and distance perception. [Work supported by the NSF.]