bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of transducer arrays with tapered side-lobe heights
Authors: Wilson Geoffrey L.
Published: October 2005

Transducer arrays for many underwater sound applications have customarily been designed for equal sidelobe levels. This is, perhaps, as much due to the convenience of the analytical Dolph—Chebyshev technique as to any specific requirement. Using a simple adaptation of a previously reported numerical technique for symmetrical arrays [G. L. Wilson, J. Acoust. Soc. Am. 59, 195 (1976)], designs can be obtained whose directional response has a taper on the envelope enclosing the side lobes. The method is equally applicable to sum and to difference patterns. Examples are given. [This work was sponsored by the Naval Sea Systems Command, Code SEA-034.]
Signal-to-noise ratio optimization in hydrophone—pre-amplifier systems
Authors: Young J. W.
Published: October 2005

The decrease in signal-to-noise ratio caused by electronic noise is an important factor in the design of an acoustic receiving system. Normally, this loss is dominated by the hydrophone, cable, and proamplifier which make up the “front-end” of the system. In this paper, the signal-to-noise degradation factor (SND) for these components is defined. It is shown that the SND can be minimized by proper impedance matching of components. This can be accomplished either by use of a transformer or by the choice of a particular interconnection scheme for a multielement hydrophone. The minimum value of SND which can be achieved is determined by the product of figures of merit (FOM) of the hydrophone and preamplifier. For piezoelectric hydrophones, the FOM is a function of fundamental material parameters and the volume of the ceramic element. The amplifier FOM depends on the equivalent voltage and current noise sources of the device. Both charge amplifier and voltage amplifier configurations have been considered. The charge amplifier is found to have inherently poorer noise performance.
Programmable system for real-time data analysis and display
Authors: Bardin J. L. , Moore V. M. , Raley D. K.
Published: October 2005

A computer-based system for real time analysis and display of acoustic data is described. A mini computer and special purpose Fourier transform hardware are combined to permit continuous FFT and auto spectral analysis, and/or coherency analysis. In addition, software is available to perform various post-FFT analyses, including spectral whitening, automatic narrow-band energy detection and harmonic analysis. A second computer has been dedicated to the formatting and displaying of analysis results. Being programmable allows operation of the computer-controlled display in various modes, such as A scan, time-frequency-amplitude alphanumeric, and combinations thereof. High-speed rotational engine radiated noise and line component data have been analyzed and results are presented.
Control of diffracted sound by means of thnadners
Authors: Wirt L. S.
Published: October 2005

The diffraction of sound around barriers partially defeats efforts to control noise by interruption of line of sight. Recent legislation, which limits allowable highway noise in adjacent communities, has stimulated interest in this problem. Currently, solid walls are used to provide partial acoustical shadows. This approach is expensive, partly because of nonacoustical engineering requirements. A review of Fresnel diffraction theory suggests that either transparency gradients or phase velocity gradients or both may be used to provide deeper shadows. Elemental Fresnel theory is slightly modified to introduce transparency or phase gradients near the diffracting edge and parametric studies are reported which define configurations that deepen the shadows. Scale model tests are described which display the trends predicted by the theory. This agreement leads to the fascinating conclusion that the best way to improve the performance of a solid wall is to cut a substantial portion of it away. Structures are suggested for the practical implementation of the method into noise barriers. A literary analogy suggests that such structures be called Thnadners.
Ground-borne noise and vibration study—Toronto Transit Commission Yonge Street Northern Extension
Authors: Saurenman Hugh J.
Published: October 2005

Following construction of the Toronto Transit Commission Yonge Subway Northern Extension (YSNE), train operations created ground-borne noise and vibration which seemed unusually noticeable in buildings near the tunnel. This paper will briefly summarize some of the conclusions of an extensive study and measurement program that was undertaken to evaluate both the characteristics of the ground-borne vibration and various procedures for reduction of the vibration and noise. The measurements included tests intended to: (1) determine the characteristics of the ground-borne vibration and noise from the transit trains operating in YSNE tunnels, and (2) evaluate the effectiveness of design features and modifications to the facilities and transit cars in minimizing and reducing the noise and vibration. Some of the specific methods of controlling ground vibration include; use of resilient wheels, reduction of the rail fastener elastomer pad stiffness to decrease the coupling between the rail and the subway invert, grinding the rail, and turning the wheels. The vibration was measured at the tunnel invert, ground surface, and the walls and floors of adjacent buildings. In addition the interior noise induced by the ground-borne vibration was measured and analyzed.
Spatial standard deviation of SPL in National Research Council's transmission loss laboratory
Authors: Chu W. T. , Lubman David
Published: October 2005

The accuracy of transmission loss (TL) determinations depends in part upon the precision of measured noise reduction (NR). This is controlled by the spatial standard deviation of sound pressure level (σ,dB) in both source and receiving rooms. National Research Council is obtaining experimental results to test a theory proposed by Lubman and Bowers [J. Acoust. Soc. Am. 44, 359(A), 1968] according to which σ is a joint property of the room and the source spectrum. A progress report is given, and measurements taken in one-third octave bands are shown to be in reasonable agreement with this theory.
Periodicity pitch difference limens in the bottlenose dolphin (Tursiops truncatus)
Authors: Defran R. H. , Caine Nancy G.
Published: October 2005

An Atlantic bottlenose dolphin (Tursiops truncatus) was trained to differentiate between similar streams of sonarlike pulse pairs. The interval between pulses of a pair was of primary interest and was varied from trial to trial. All signal parameters were designed to simulate the emitted signals and returned echoes present in a dolphin sonar task. Discriminative responding to variations in the interpulse interval allowed for an estimation of the dolphin's temporal discrimination ability. Psychophysical functions constructed from the data were orderly, asymptotic, monotonically related to the duration of the comparison intervals, and statistically reliable. Psychophysical thresholds, defined as the 75% correct level of responding, indicated that the dolphin was capable of resolving differences as fine as 100 μsec. Further, the results confirmed that the dolphin's temporal discrimination is most accurate for pulse pair intervals simulating the shortest distances. Results were interpreted within the framework of a periodicity pitch analysis. Extrapolation of the data suggest that sonar discrimination of distance in the dolphin involves a complex frequency discrimination rather that a correlation discrimination.
Rare earth-iron magnetostrictive underwater sound transducer
Authors: Meeks S. W. , Timme R. W.
Published: October 2005

A piston-type k33-mode underwater sound transducer utilizing rods of 27%-terbium-73%-dysprosium iron alloy as the transduction element is described. The broadband frequency operation permits intercomparison of the terbium-dysprosium iron and ceramic element, as well as comparison with predictions based on basic material property measurements. An equivalent circuit which successfully describes the transducer performance and data on free-field voltage sensitivity, transmitting current response, coupling coefficient, directivity, efficiency, linearity, and power drive are presented. Predictions based upon the equivalent circuit for the performance of a laminated transducer are discussed. Design problem areas resulting from the requirement of large magnetic fields, eddy current losses, and alloy brittleness are discussed and compared to design problems encountered with ceramic transduction materials.
Development of a cost effective 65-kHz tonpilz element
Authors: Tighe F. , Douglas G. R.
Published: October 2005

A 65-kHz tonpilz element was designed, constructed, and calibrated. The element is to be used as a pump array for an underwater parametric receiving system. To reduce the cost of the array, the component parts and Q were minimized and the radiation-head size was maximized. In order to avoid head flexure, the size of square radiation heads to tonpilz elements rare typically less than 0.7 λ. The element in this report has a head 1.35 λ square, reducing the number of elements for a given aperture by a ratio of 3.7: 1. The measured 3-dB bandwidth was approximately 16 kHz, centered at 65 kHz, representing a Q of 4.
Determination of glottal area based on digital image processing of high-speed motion pictures of the vocal folds
Authors: Davis S. B.
Published: October 2005

The extraction of glottal-area data using frame-by-frame analysis of high-speed motion pictures of the vocal folds has previously been a time-consuming process requiring manual interaction. Completely automatic extraction of glottal-area data may be realized by two-dimensional digitization of sequential frames of high-speed film followed by computer algorithms for edge detection and area calculation. In a recent feasibility study, six photographs (2.56 in.×2.56 in. each) depicting successive discrete movements of the vocal folds during the open phase of one pitch period were digitized (512 points×512 points×256 gray levels each) and stored. Brightness, contrast, and normalization algorithms were utilized to compare the observed detail in the digital representations with the original data. The glottal area of each frame was automatically calculated from the digitized images with no manual intervention, and the areas were compared with planimeter measurements for accuracy. The results indicate that it is possible to apply digital image processing techniques to accurately display physiological details and to automatically extract the glottal area from high-speed motion pictures of the vocal folds.
Recruitment and discharge patterns of single motor units during speech production
Authors: Sussman H. M. , Powers R. K. , MacNeilage P. F.
Published: October 2005

Study of single motor unit (SMU) activity during rapid isotonic contractions, such as those characterizing speech, provide a closer look at the inacessible central mechanisms responsible for the encoding of the speech motor program. This study represents a quantification of the discharge and recruitment patterns of SMU's in the anterior belly of digastric, a muscle active in bringing about jaw lowering. Using a highly selective intramuscular electrode and computerized analysis procedures the firing rate, recruitment intervals, and various temporal intervals between SMU activity and articulatory events were obtained. Results to be discussed include: (1) greater isotonic versus isometric discharge rates for the same motor unit; (2) higher maximum discharge rates for later and larger recruited motor units; (3) relative invariance of recruitment order; (4) temporal sequence of SMU activation in relation to initiation of jaw lowering and speech audio signal: and (5) relationship of SMU activity to articulatory displacement and velocity. Implications of these results towards a further understanding of the encoding mechanisms of speech will be discussed.
Reaction of artic wildlife to gas pipeline related noise
Authors: Ruth J. S.
Published: October 2005

Several studies on the reaction of arctic animals to noise emissions from gas compressors and aircraft are reviewed. Wildlife species examined include caribou, Dall sheep, moose, grizzly bears, wolves, snow geese, Lapland longspurs, and bald eagles. Degree of reaction to noise disturbance was found to vary with group size, sex, season, activity engaged in prior to disturbance, previous exposure to noise source, and distance from noise source.
Acoustic sounding of the atmosphere after ten years
Authors: Hall Freeman F.
Published: October 2005

It has now been ten years since the Weapons Research Establishment in Australia precipitated the modern era of atmospheric acoustic sounding with the operation of their 15-m dish-equipped sounder in November 1966. The spectacular facsimile records of atmospheric structure resulting from this pioneering effort have caught the interest of a large segment of the atmospheric sciences community. The number of such sounders now operated around the world approaches 200. From the outset, the utility of the devices for measuring the height of temperature inversions as the atmosphere passes through its diurnal cycles was recognized, and this ability is being exploited by many industrial and governmental groups concerned with air pollution problems. In addition, the ability to quantitatively measure the intensity of the scattered sound has led to a much improved understanding of the structure of atmosphere turbulence. Frequency analysis of the scattered signals allows accurate measurements of the three dimensional winds throughout the planetary boundary layer, and several prototype wind profiling systems are now in routine operation. The discipline still has many problems to be solved and questions to be answered: Can small scale turbulence measurements be extrapolated to predict pollutant diffusion? Can molecular and scattering attenuation coefficients be determined well enough to enable accurate measurements of turbulence throughout the planetary boundary layer? Can advantage be made of the coherence properties of the transmitted signal? Can temperature and humidity profiles be measured acoustically? Can acoustic Doppler wind sensors utilizing modern digital techniques be made inexpensive enough for urban networks to be established?
Acoustic noise cancellation techniques
Authors: Keeler R. Jeffrey
Published: October 2005

The environment noise that plagues acoustic echo sounder systems is described as a nonstationary, non-white and non-isotropic random process. Classical detection and estimation theory do not treat this type of noise and consequently ad hoc procedures have been developed which will reduce the detrimental effects of acoustic noise. For simple monostatic echosondes the noise limits the dynamic range of received echoes by masking low-level signals and for Doppler echosondes the noise generates spikes in the received power spectrum which cause the variance of the resulting wind estimates to be increased. Several alternative schemes are given for reducing the effect of noise in the spectrum of such power-spectrum-based Doppler processors. Results from the implementation of some of these methods are shown. A time domain adaptive noise cancellation (ANC) technique is described which potentially offers a 5–20-dB improvement in SNR over any power spectrum noise subtraction scheme. The ANC method uses an external reference noise to estimate the noise on the signal which is then subtracted from the primary signal input, Thus the reference noise that is correlated with the primary input noise is effectively cancelled. Being a time domain preprocessor ANC can be employed on any echosonde.
Propagation of dolphin echolocation signals
Authors: Au Whitlow W. L. , Floyd Robert W. , Haun Jeffrey E.
Published: October 2005

The propagational characteristics of high-frequency echolocation signals (peak energies above 100 kHz) of the Atlantic bottlenose dolphin (Tursiops truncatus) in open waters were determined by a series of measurements conducted while the animal performed a target-detection task. The animal was trained to station in a “chin-rest” device so that the vertical beam pattern could be measured with a vertical array of hydrophones and the horizontal beam pattern could be measured with a horizontal array. The animal's signals as a function of distance from the animal out to 2 m were measured with a horizontal array of hydrophones placed directly in front of the animal. These measurements were used to study the relationship of the signals in the nearfield and farfield of the animal's sonic beam. The relationship of the signals measured with a contact hydrophone place on the animal's rostrum and on the melon with the signals measured at 1 m and at the target was also studied. It was found that the 3-dB beamwidth was approximately 8.5° for both the horizontal and vertical beams. The major axis of the vertical beam was directed at an angle of 20° above the plane defined by the animal's teeth. it was also found that the farfield begins at approximately 0.5–0.6 m from the tip of the animal's rostrum.
Preprocessors for real-time spectrum analysis
Authors: Andrews M.
Published: October 2005

An adaptive nonrecursive (NR) filter with application to spectrum analysis is presented. The adaptive nature is implemented with a weight adjustment algorithm (LMS) on the filter that performs a steepest descent minimization of mean-square error. The difference between an “interference” or coherent representative of it and the raw signal under analysis via its spectral content is defined as the error. A priori knowledge of the disturbances consists of the spectral content of the disturbances without regard to amplitude or phase information. The algorithm is manifest with a digital arithmetic unit using high-speed logic in a robust 512 weight digital filter fabricated with current integrated circuit technology. The experimental configuration is described along with improvements currently attainable with advancements in technology. Applications to spectrum analysis, whereby unknown disturbances degrade interpretation of spectrum signatures in bearing studies, acoustic phenomena, and sonar signal analysis, is described. Adaptive filter behavior with stationary as well as nonstationary input signals are presented. It is shown that for some narrowband as well as broadband disturbances the filter tracks and adaptively rejects disturbance in real time so as to present uncluttered renditions of the spectrum signatures or spectograms for analysis.
Nearfield data from small and large explosions. I. Time-domain analysis
Authors: Goertner Jean A. , Blatstein Ira M.
Published: October 2005

In a joint sea test of the Naval Research Laboratory, the White Oak Laboratory has obtained nearfield explosion data from 8-, 48-, and 1000-lb TNT charges. Pressure-time measurements at constant range were made, with multigain recordings at two depths. Recordings were made using both a ceramic hydrophone and a tourmaline piezoelectric gage. The experiment will be described and experimental data presented. These shallow depth-constant range data validate previous results for underwater explosion similitude expressions for pressure, decay constant, etc., that were largely obtained from data where range and depth effects were intertwined. The data also extends to shallower depths the reduced parameter curves currently employed for predicting underwater explosion effects and for modeling acoustic source levels. Discussion will focus on how comparison of various records are useful for comparing different sensor outputs and for studying nonlinear effects—factors that influence source level determination. [This work was funded by DNA.]
Antisymmetric modes of vibration of a circular plate elastically restrained against rotation and subjected to a hydrostatic state of in-plane stress
Authors: Laura P. A. A. , Luisoni L. E. , Arias A.
Published: October 2005

The analysis of flexural vibrations of plates with edges elastically restrained against rotation is of interest to the design engineer since ideal supports or clamps are difficult to obtain in practice. A survey of the literature reveals that several investigations have been performed in the past on (a) vibrating circular edges (without in-plane loading) and (b) vibrating simply supported and clamped circular plates subjected to hydrostatic in-plane loading. The present paper deals with the determination of very simple, approximate frequency equations which allow prediction of natural frequencies in the case of a vibrating circular plate which executes antisymmetric modes. It is shown that use of simple polynomial expression and a variational approach leads, in some cases, to numerical values which are more accurate than those available in the technical literature. The approach followed in the present investigation can be extended in a straightforward fashion to the case where the edge has translational flexibility.
Time-average holographic study of a singing wine glass
Authors: Tonin R. , Bies D. A.
Published: October 2005

Previous attempts to determine the motion of a free edge vibrating cylinder using time average optical holography have been inconclusive. On the assumption of strictly radial motion attempts at the interpretation of the fringes produced in orthogonal views has lead to the contradiction that the implied motion motion was not single valued [S. D. Liem et al., J. Sound Vib. 29, 475–481 (1973)]. In the latter reference it was suggested that the problem lay with the physical location of the optical fringes in the reconstructed image. However, as already shown by Rayleigh the motion of the free edge of a vibrating cylinder has both radial and tangential components of displacement and this point had not been taken into account. In this paper it is shown how the theory of time-average optical holography may be extended to account for generalized elliptic motion of a vibrating surface under study and how the optical system may be arranged to unambiguously interpret the motion. It is shown that good argument is obtained between the predicted and observed motion for a singing wine glass and for a free edge rectangular cylinder vibrating in a Love mode.
Loss and coupling loss factors of two coupled dynamic systems
Authors: Maidanik G. , Brooks J. E.
Published: October 2005

The Statistical Energy Analysis (SEA) has been employed to define and estimate the response of complex dynamic systems. Often a complex dynamic system is conveniently divided into a number of subsystem—basic dynamic systems. The complex is then modeled in terms of a number of coupled (basic) dynamic systems. Within the format of SEA the descritpion of the model is given in terms of the loss and coupling loss factors of the dynamic systems that compose the complex, Thus, to define the model, means must be devised to obtain the values of the loss and coupling loss factors. In this paper the experimental methods for obtaining these values are considered and scrutinized. For the most part considerations are limited to a complex consisting of two dynamic systems; the elements of an extension to higher forms of complexes are, however, included. It is shown that to obtain experimentally the loss and coupling loss factors one is required to conduct not only steady state but also transient experiments. The role of the reverberation time determined in the transient experiments is of particular interest.
Syllable synthesis
Authors: Mattingly Ignatius G.
Published: October 2005

In an attempt to provide a more direct representation of coarticulatory effects on spectral and temporal patterns of speech than is possible with a segmentally organized algorithm for synthesis by rule, an algorithm now being developed is organized around the syllable. The input is a phonetic description of the utterance in terms of syllable features and a set of rules. The rules determine the translation of the feature description into a description in terms of articulatory influences, such as those of the current vowel, the following vowel, initial and final semivowels, initial and final consonants. Each such influence is represented by a set of target values for formant frequencies and by an exponential function of time; and the targets, the rates of growth and decay of the influence functions, and their timing relative to one another, are specified in the rules. The influences are ordered, and a formant-frequency value at a given time is determined by iteratively computing the sum of the target value associated with the nth influence, weighted according to its influence function, and the value determined by the first n − 1 influences. This algorithm is a part of a synthesis by rule program written in FORTRAN for the PDP11/45. [Work supported by NIH and VA.]
Evaluation of rule-generated pitch contours
Authors: Melby A. , Millett R. , Strong W. J. , Lyric E. G.
Published: October 2005

Research in modifying pitch contours in order to cause various readings to be perceived for a sentence (reported on at the November 1975 Meeting of the Society) has led to a computer algorithm for generating pitch contours from a semantico-syntactic representation of a sentence. These rule-generated pitch contours were evaluated according to two criteria: naturalness of intonation and “intelligibility” of intonation. Subjects were asked to rate sentences for naturalness on a scale and further to select the “natural” sentences from pairs of sentences. In a test of “prosodic intelligibility” subjects were asked to select which version of a sentence they heard (where stress was indicated by underlining or where various possible contexts were suggested). Stimuli consisted of arrangements of 35 distinct sentence versions synthesized from 12 sets of LPC analysis data, varying only the pitch (fundamental frequency) specifications. Included in the stimuli were versions with natural, rule-generated, manually specified, and monotone contours. Composite naturalness scores from part of the test placed rule-generated contours at 3.6 and the natural contours at 4.1 on a scale from 1 to 5. Further results will be presented, as well as a discussion of how the results suggest specific areas of further research.
Computer-sorting procedure for inverting functions
Authors: Mathews M. V. , Atal B. , Chang J. J. , Tukey J. W.
Published: October 2005

For, ȳ=f(x̄), x̄ and ȳ being vectors, we assume ȳ may be computed from x̄, but x̄=f−1(ȳ) cannot be computed directly and x̄ may be multivalued. An important example is the vocal tract function where x̄ describes the articulation and ȳ describes the resulting sound. Inversion by sorting consists of computing ȳ for many values of x̄ and sorting the resulting ȳ, x̄ pairs into a convenient order according to ȳ. x̄ corresponding to a given ȳ is then obtained by looking up ȳ in the sorted data. Multiple values of x̄ will be adjacent in the sorted data. Subspaces in x̄, denoted fibers, may map onto a single ȳ. There may be forbidden regions in ȳ which cannot be reached by any x̄. The local nature of f(x̄) including the fibers and forbidden regions are determined by linearization in a neighborhood. Larger regions are computationally explored by extending the linear neighborhoods in small steps.
Generalization for damping in the acoustic tube model of speech production
Authors: Gray A. H. , Markel J. D. , Wakita H.
Published: October 2005

The widely used method of vocal tract modeling proposed by Wakita [IEEE AU-21 pp. 417–427] is a lossless model which places all possible damping at the glottis. In addition, the lip radiation impedance for this model is, by definition, zero. Elementary recursion relationships allow unique transformations between the inverse filter A(z) and the acoustic tube area functions. In this paper, the acoustic tube model is generalized to allow for arbitrary real attenuation within each acoustic tube section and to allow for the lip radiation impedance form described by Flanagan [Speech Analysis (Springer-Verlad, Berlin, 1972), 2nd ed. p. 36]. The approach suggested in Markel and Gray [Linear Prediction of Speech (Springer—Verlag, Berlin, 1976), p. 88] is pursued here and it is shown that a recursive expression for a new inverse filter can be obtained in terms of the area functions, the glottal termination, the internal losses, and a realistic lip radiation impedance. Theoretical and experimental results will be discussed.
Behavioral assessment of kanamycin-induced hearing loss in the guinea pig
Authors: Petersen M. R. , Prosen C. A. , Moody D. B. , Stebbins W. C. , Hawkins J. E.
Published: October 2005

The effect of chronic kanamycin administration on absolute auditory thresholds measured with the operant conditioning procedure described in the previous paper was examined in four guinea pigs. The absolute threshold for five different frequencies was measured daily, thus permitting construction of an audiogram which ranged from 125 Hz to 34 kHz within a two-day period. Following establishment of a predrug baseline the animals received 200-mg/kg injections of kanamycin daily for 15 to 30 consecutive days. In the course of drug treatment the animals suffered permanent hearing losses which progressed gradually from the higher to the lower frequencies. The maximum threshold shift observed at any of the test frequencies was approximately 50 dB. In fact, shifts in absolute threshold at frequencies most severely affected by the drug were within a range of 35–50 dB. The correspondence between the hearing impairments determined behaviorally and the cytocochleograms constructed from light microscopic examinations of surface preparations of the organ of Corti will be discussed. [Supported by Research Grants NS05077 and NS05065 and by Program Project Grant NS05785 from NINCDS.]
Speech perception by the chinchilla: Categorical perception of synthetic alveolar plosive consonants
Authors: Kuhl Patricia K.
Published: October 2005

Kuhl and Miller [Science 190, 69–72 (1975)] recently demonstrated that in an identification task the chinchilla responds to (“labels”) an alveolar synthetic-speech continuum as though an abrupt qualitative change occurs at the place where English speakers hear a change from /da/ to /ta/. Discrimination functions for these same stimuli have now been obtained. The animal's task is to detect a change from a repeating “standard” stimulus to a “comparison” stimulus and report that change by crossing a midline barrier to avoid shock. The standard stimuli are 0, +10, +20, +30, +40, +50, +60, +70 and +80 msec VOT. The VOT value of the comparison stimulus is gradually changed until it approaches the VOT value of the standard. The animal's threshold (the minimum Δt detected with 75% accuracy) is measured for each standard stimulus and is best when the standard is +30 msec VOT, that is, at the animal's perceptual boundary as defined in the labeling experiments. This agreement between the labeling and discrimination data demonstrates categorical perception for a voiced-voiceless continuum by an animal listener. [Supported by NIH grant NS 03856 to CID.]
Decay of the acoustic reflex during a prolonged exposure to noise
Authors: Gerhardt Kenneth J. , Melnick William , Ferraro John A.
Published: October 2005

Decreases in sound attenuation resulting from acoustic arousal of the middle-ear-muscle reflex were investigated during an 8-h exposure to an octave band of noise centered at 0.5 kHz at 95 dB SPL. Chinchillas were chronically implanted with round-window recording electrodes. Changes in the amplitude of the cochlear microphonic during continuous noise exposure reflected activity of the acoustic reflex (AR). The 8-h exposure was composed of four consecutive 2-h periods separated by 11-min “quiet” intervals. The AR remained active throughout each of the four exposures, but the magnitude of the reflex decreased approximately 30%–50% within each 2-h period. This decaying process appeared to reach an equilibrium following 8–30 min of exposure after which a constant level of effect was maintained. The initial magnitude of attenuation measured after noise onset decreased with each additional exposure period.
Noise impact evaluation of a military airbase
Authors: Ivey E. S. , Russell G. A. , Hicks A.
Published: October 2005

A 24-h noise survey was conducted in the vicinity of Pease AFB, Portsmouth, NH, using both automatic and manual sampling techniques. The manual sampling procedure used allowed the noise contributions from all military aircraft operations to be distinguished from the residual noise levels. By processing the manually sampled data twice, once with the military aircraft noise signals included and once without, it was possible to define a “with and without noise impact” of the military aircraft operation on the surrounding community. Results of the analysis indicated a good correlation between the manual and automatic sampling methodologies and with CNEL contours previously developed for Pease AFB. Significant differences between the “with and without military aircraft” LEQ and LDN noise levels were found at distances of five miles from the base. The measurement and analysis methodology used in this study provides a unique noise impact assessment tool for community noise studies in the vicinity of operating airports. Although only very simple measurement and data reduction techniques are required, this assessment methodology yields useful “with and without” information. As such, it can be applied in a variety of land use planning situations.
Problems of guinea pig training and how to solve them
Authors: Walloch R. A. , Fenwick J. A.
Published: October 2005

Twenty-two guinea pigs were trained to detect a tone with a food reward. Common behavioral problems were handled in the following manner: (1) “Freezing” or fear responses were easily obviated by allowing the animals to spend a night in the training cage. (2) Initially the lever was baited to induce pressing. (3) “False positives” were punished with a 10-sec “time out,” and the “false positive” rate was reduced by increasing the number of observing responses needed to activate the tone. (4) Failures to detect the tone were also reduced by increasing the number of observing responses. (5) Despite an adequate feeding schedule, motivational levels of the quinea pigs remained a problem. [Work sponsored by the Deafness Research Foundation, Zenith Hearing Instrument Corp. and N.I.H.]
Positive reinforcement behavioral system for tone detection and choice reaction times in the cat
Authors: Orr J. L. , Moody D. B. , Stebbins W. C.
Published: October 2005

The apparatus and training necessary to test cats in a two-response-key auditory discrimination and choice reaction time paradigm is described. Cats initiated a cycle of the discrete trial procedure by depressing two response pedals and holding them down until a light which marked the trials occurred. During trials, release of the right and left response pedals were defined as reports of tone presence and tone absence respectively. Correct release responses were reenforced with liquid food. Incorrect responses or failures to respond were not reenforced. Trials were terminated by a response or after 1.6 sec, whichever came first. Reaction times were defined as the time from trial onset until the occurrence of a response. Operation of the system was demonstrated with the method of constant stimuli. Half the trials were blanks in which no tone was presented; on the remaining trials each of 4 SPL of an 8-kHz tone were equally likely. Detection was direct function of tone intensity and median reaction time to correctly report the presence of the tone was an inverse function of tone intensity. [Supported by Research Grant NSO5077 and Program Project Grant NSO5785 from NINCDS.]
Hearing in large and small dogs (Canis familiaris
Authors: Heffner H.
Published: October 2005

Audiograms were determined for four dogs ranging in size from 4.5 to 30 kg. The dogs were tested using a two-choice procedure with a ready response, i.e., the dogs initiated a trial by licking a center water spout and were rewarded with water for licking a left water spout if a tone was present or for licking a right water spout if no tone was present. At a level of 60 dB SPL, the dogs were able to hear as low as 62 Hz and as high as 45 kHz with a best frequency of 8 kHz. In spite of the large variation in head size, there appeared to be no difference between the ability of large and small dogs to hear high frequencies. Thus it appears that the inverse relationship between the functional distance between the two ears and high-frequency hearing may not apply to variation within a species. [Supported by NIH grants NS 12992 and HD 02528.]
Partial masking effect in the monkey as measured by a behavioral technique
Authors: Moody D. B. , Stebbins W. C. , Rudy M. C.
Published: October 2005

Macaque monkeys were trained with a positive-reenforcement behavioral procedure to release a response key when a tone was presented. The latency of this release reponse is an inverse function of the sound pressure of the tone over a wide dynamic range, and can be used as a behavioral index of relative loudness. When tested on this procedure in the presence of moderate levels of masking noise, the monkeys showed the greatest effect of the masker for low levels of test tone while the masker became less effective with more intense test tones. These data thus mirror the partial masking phenomenon described for human subjects and are similar to loudness recruitment data previously demonstrated in humans and monkeys. When maskers of different bandwidths were equated for amount of threshold shift, no consistent difference between the bandwidths in effectiveness at higher test-tone levels was observed; that is, the more rapid growth of loudness associated with narrower band maskers which has been reported in humans was not observed in all subjects. [Supported by Research Grant NSO5077 and Program Project Grant NSO5785 from NINCDS.]
Primate auditory localization: the locatability of different bandwidth signals
Authors: Brown C. H. , Beecher M. D. , Moody D. B. , Stebbins W. C.
Published: October 2005

The ability of monkeys (Macaca) to detect a change in the location of a sound in space was psychophysically assessed through the employment of operant-conditioning techniques. Contact with a response disk initiated a train of acoustic stimuli pulsed from a standard location (0° azimuth). Following a variable number of pulses the stimulus changed its spatial position to one of several comparison locations. If the monkey reported this change in location by releasing the response disk it received food for reenforcement. Thresholds for the minimum discriminable change in the horizontal coordinate of sound in space (azimuth) were determined by the method of constant stimuli under free-field conditions in an anechoic chamber. The monkeys were tested with a parametric array of pure tones and signals of different bandwidths. The results indicate that the inverse relationship between threshold and stimulus bandwidth found in a preliminary study [C. H. Brown, M. D. Beecher, D. B. Moody, and W. C. Stebbins, J. Acoust, Soc. Am. 58, 124S (1975)] characterizes Macaca localization over much of its range of hearing. [This research was supported by NSF Grant No. BMS74-20050 and Program Project Grant NSO5785.]
Interaural time-difference threshold in pig-tailed monkeys (M. nemestrina
Authors: Houben D. , Gourevitch G.
Published: October 2005

A brief 60 dB SPL diotic tone burst was delivered to the monkey, followed by a dichotic burst of interaurally delayed tones. The monkey was trained to respond on a right lever when the phase of the dichotic burst was leading at the right ear, and on a left lever when the phase was leading at the left ear. The side of the leading ear and the magnitude of the interaural delay were chosen at random from trial to trial. Interaural time delay (ITD) threshold was taken as the time disparity correctly lateralized on 75% of the trials and was measured at eight frequencies ranging from 250 Hz to 2 kHz. The ITD function decreases from 250 to 750 Hz; thereafter it remains constant at about 50 μsec. This function parallels the human curve, [J, Zwislocki and R. S. Feldman, J. Acoust. Soc. Am, 28, 860–84 (1956)] although it is elevated by about 30 μsec. Humans cannot utilize ongoing time differences to lateralize pure tones above 1300 Hz, whereas the monkeys were able to lateralize up to 2000 Hz. The importance of ITD's in monkey auditory localization is discussed.
Significance of land use elements in developing noise maps
Authors: Manns Basil H. , Holecrabs Sharon B. , Hershey Robert L.
Published: October 2005

The procedure used to relate noise level to land use is basically through a simple function of population density. The 100-site study conducted by the U. S. EPA in 1973 attempted to verify the premise that outdoor noise does correlate with population density. The function derived has been used extensively in airport planning to estimate the indigenous noise in a community. However, extreme care must be taken in using the results of this 100 site study to develop noise maps directly, since they exhibit wide scatter as a function of various land use elements. The uncertainty of the procedure and the significance of seemingly insignificant parameters have been investigated (show actual sites variation). An algorithm has been developed to estimate noise levels at any given point in a community on the basis of land use parameters. This algorithm involves the construction of artificial traffic noise levels using the population density and the road configuration. The algorithm can be expanded to prepare noise maps by using clusters of homogeneous land use elements. Emphasis is given to surface transportation noise sources rather than aircraft operations, since this type of noise impacts more people than any other single category. A discussion is also included as to how a planner or designer may use such a statistical procedure in estimating community noise. The algorithm may be used by a planner, together with noise models of airports, rapid transit systems, and industrial sites, to produce comprehensive noise maps. Examples of noise maps are presented for the Washington Technical Institute complex in Washington, D. C., the Los Angeles Airport area, and the Lindberg Field area in San Diego.
Stop bursts and transitions as functionally equivalent, context-sensitive cues
Authors: Dorman M. F. , Studdert-Kennedy Michael , Raphael Lawrence J.
Published: October 2005

The experiment reported here was primarily designed to test the functional invariance of stop bursts as perceptual cues. Bursts from three sets of nine CV syllables for each stop-consonant place of articulation were transposed within each set and played for listeners. Although some measure of perceptual invariance was found within each of the labial and apical sets, and within two subsets for the velar bursts, the perceptual weight carried by the bursts attained significance in few of the syllables tested. Further, the perceptual weight of the bursts and formant transitions of the syllables tended to be reciprocally related. These two cues appear to be functionally equivalent, context-dependent cues, each contributing to the rapid spectral changes that follow consonantal release. The results indicate the importance of the role of front cavity resonance in signaling place of articulation.
Perception of synthetic unsteady vowels under various formant conditions
Authors: Kuwahara Hisao , Sakai Hisao
Published: October 2005

Aural tests were done for stimuli consisting of three-vowel chain synthesized by means of terminal-analog speech synthesizer. The second-formant frequency corresponding to the middle vowel of the stimuli changed along a stimulus continuum from /u/ to /i/, while other formants were held constant. The initial and final vowels of the stimuli were the same vowel /u/, and the duration and frequency of the second formant corresponding to the middle vowel had different values. The formant transition changed linearly with different rates. Subjects identified the middle vowel of each stimulus as one of Japanese vowels /u/ or /i/. The results indicated that the changed rate of the formant transition and the duration of the midpart of steady state had little effect on vowel perception if the whole duration between the initial and final vowels became longer than 50 msec.
Perception of voicing in final stops
Authors: Wolf Catherine G.
Published: October 2005

The perception of voicing in final stops was investigated. Syllables which had been truncated at various points were presented to subjects for identification under two response conditions. In one condition, the response set consisted of two consonants (one voiced, one voiceless). In the other condition, subjects could choose either of the two consonants, or report that no final consonant was heard. The results indicated that the formant transitions, closure, burst, and vowel duration are important in determining whether a stimulus is heard as voiced or voiceless. In addition, there are coarticulation effects occurring as early as the first 50 msec of the preceding vowel which appear to affect the pattern of voiced/voiceless judgments. A common basis for the perception of voicing in initial and final stops is also considered. [Work supported by NINCDS.]
Influence of vowel height, intensity, and temporal order on pitch perception
Authors: Chuang Chiu-Kuang , Wang William S.-Y.
Published: October 2005

Recently, it has been observed that high vowels are produced with a higher F0, even in tone languages. Earlier, H. Fletcher reported that louder pure tones are perceived as having a lower pitch, but only in the range 50 to 500 Hz, which is the range of F0 in speech. Here we report some experiments which investigate these relations. Fifteen subjects are asked to judge the relative pitch of pairs of synthesized vowels. The vowels are /i, e, u, a/ with intensity differences (ΔI) of 0, 10, 20, and 30 dB SPL, and at frequency differences (ΔF0) of 0, 1, 2, and 3 Hz, with a base frequency of 100 Hz. Each vowel is 300 msec long and the inter stimulus interval is 400 msec. The orthogonal combination of these factors, i.e., four vowel types, four ΔI's, four ΔF0's, and the two positions within each pair, makes up a total of 512 stimulus pairs. The interaction between pitch perception and vowel height is highly significant statistically. Pooled across all subjects, /a/ is heard as 2.2 Hz higher than /u/, 0.8 Hz higher than /i/, and 0.2 Hz higher than /e/. The intensity factor by itself appears to have no effect on pitch perception, but interacts with the postion factor in influencing pitch perception. The negative correlation between production and perception in the relation between vowel height and pitch is interpreted as the result of a compensation mechanism mediating between production and perception. [Work supported by NSF Grant No. BNS 76-00017-Wang-2/78J34.2.]
Categorization of nonspeech signals
Authors: Forrest Karen
Published: October 2005

Investigations of speech perception have demonstrated the existence of discrete perceptual categories when stimuli vary along a continuous frequency dimension. Nonspeech signals that vary along a continuous frequency dimension, when interspersed with speech signals, are not perceived in a categorical manner. This has led to the assumption that speech is an acoustic signal with properties that are different from nonspeech acoustic signals. The present study was designed to determine the validity of this distinction as it relates to categorization. The stimuli used were complex tones composed of a constant 800-Hz tone and a glide with a variable starting point and a fixed endpoint at 2 kHz. The rate of frequency change was also varied. All stimuli were 30 msec in duration. The stimuli were separated into two groups—Group A stimuli increased to 2 kHz, and Group B decreased to 2 kHz. Subjects were required to group the stimuli into appropriate categories. They received no information about what stimulus belonged to what category, but feedback was provided after each trial. Initial data show that subjects were able to categorize the stimuli with a high degree of accuracy after a rather limited period of exposure.