bluuebunny/crossref_metadata_2025 huggingface dataset:
More on the aftereffects of noise
Authors: Nagel D. C. , Dake K. , Schreiner J. , Tanner T. A.
Published: October 2005

In an attempt to further explore the nature of the aftereffects of exposure to noise first reported by Glass and Singer [Urban Stress (Academic, New York, 1972)], a total of 40 persons were first exposed to an intermittent, unpredictable composite noise similar to that used in the original study. During the noise exposure, the subjects were also asked to perform a demanding Stroop memory competition task. Since intellectual ability has been shown to interact with simultaneous noise exposure [M.E. Bryan and I. Colyer, Acustica 29, 228–233] a standard short form IQ test was also administered to each subject to assess the relationship between this variable and any aftereffects of the noise exposure. Following the noise exposure period, each subject was given a proofreading task and geometric puzzle solving task, again similar to those originally used by Glass and Singer. A control group of 40 subjects performed all tasks in quiet. Overall, no differences were found in the proofreading performance between the noise and no-noise exposed subjects. Noise-exposed subjects did, however, show significantly less perserveration in the solution to insoluble puzzles, a result similar to that found in the original work. IQ correlated positively with performance on all tasks but was not a predictor of the differential effects of noise on the puzzle task performance.
Noise levels measured within aircraft during conditions of takeoff, climb and low, and normal and high cruise
Authors: Gasaway Donald C.
Published: October 2005

Most aircraft cockpits contain noise that may interfer with communications, result in auditory fatigue, and cause permanent noise-induced hearing loss. Also, noises that cause crewmembers to employ sustained loud vocal effort may contribute to increased general fatigue. The author has completed a study of noises encountered within various fixed- and rotary-wing aircraft during different phases of flight and this presentation summarizes the results. A-weighted levels are reported for 12 groups of aircraft during takeoff, climb and low, normal and high cruise. The aircraft groups are classified according to engine type and the manner of power-plant-to-vehicle mating used. Mean. variance, and standard deviation are reported for each group. Although the number of aircraft sampled within each category varied, the totals for each condition of flight are reasonably representative. For example, during conditions of normal cruise, 492 fixed-wing and 87 rotary-wing vehicles are reported and ambient mean A-levels ranged from 89.5 to 101.9 for fixed-wing aircraft and from 98.1 to 103.5 for rotary-wing vechicles.
Contextual effects in category judgments of noise
Authors: Nagel D. C.
Published: October 2005

Category judgments of the annoyance produced by single aircraft flyover noises and broad-band synthetic noises were obtained in three experiments. Subjects were instructed to rate each noise on a 12-point scale of annoyance. The sound levels used in the several experiments ranged between approximately 65 and 90 dBA. Within each of the experiments, subjects judged a given set of noises in several contexts, which were defined in terms of the distribution of sound levels heard in any given experimental session. In some sessions, for example, stimulus sequences were determined such that loud sounds predominated. In others, quiet sounds predominated. In all three experiments, the rating of a given sound was found to be systematically related to the context in which the noises were judged. Specifically, if in a given session loud sounds predominated, the ratings for all sounds heard in that session were reduced relative to those obtained in a neutral context. The results are compatible with a model which suggests that persons making such judgments tend to use response categories with equal frequency.
Ear protector attenuation of impulse noise
Authors: Kobal Michael T. , Weissler Pearl G.
Published: October 2005

The attenuation provided by seven different circumaural hearing protectors on the newly-standarized aluminum artifical head was measured for parallel and perpendicular sound incidence. The impulse sound source was a 38-caliber handgun shooting blanks, which created a 150-dB re 20 μPa peak sound pressure level with an A-duration of 0.13 ms. The ear protector was 1 m from the gun. The incident noise impulse external to the ear protector was measured with a “1/8-in.” condenser microphone and the resultant noise inside the ear protector was measured with a “1/4-in.” condenser microphone. These two impulse signals were captured in a digital transient storage device from which both a pressure amplitude versus time plot and a magnetic tape recording were made. The tape recording was used to obtain a spectral analysis employing a time-compression real-time analyzer. The attenuation of the peak levels and the energy-density spectrum of the ear protector was found by suitable comparison of the external and internal signals. The energy density results show that most of the energy of the noise inside the ear protectors is at low frequencies.
Development of vibration pick-up type auditory canal microphone and its daily application
Authors: Ono Hiroshi , Saito Shigeji
Published: October 2005

As voice transmitting microphones, especially in noisy environments, as well as in situations in which the free use of both hands is restricted, monodirectional, noise canceling, and laryngeal microphones have been widely used. These conventional transducers, however, have not been satisfactory with regard to the elimination of the ambient noise, positioning of the microphone, the feeling of use, and the clarity of the voice. We developed a vibration pickup-type auditory canal microphone by use of a piezoelement which is not influenced by sound pressure itself. The advantage of use of this microphone is that there is no problem in security and safety thanks to rich information from outside because this microphone works well without tight insertion into the ear canal. In addition, this microphone can be used as a howlingless microphone because it does not sense sound pressure. The nature of non-interference had made it possible to intergrate it with a sound-pressure-type earphone, permitting simultaneous communications without closing the auditory canal. Moreover, it does not need an ear muff for transmission even in highly noise levels of more than 100 dB thanks to its excellent ability of shutting noise off.
Acoustic correlates of stress in Russian
Authors: Purcell Edward T. , Brandt Nancy S.
Published: October 2005

Previous studies have examined the effects of various acoustic parameters on the perception of stress in English and other languages. Morton and Jessem [Lang. Speech 8, 159–181 (1965)] found that a raised F0 produced far greater effects on stress perception than did variations in intensity or duration. Fry [J. Acoust. Soc. Am. 27, 765–768 (1955)] showed that duration is more effective than intensity in cuing stress, though both are involved. Fry [Proc. 5th Int. Congr. Phon. Sci., Munster, 1964, 306–311 (1965)] found that vowel formant frequency is less effective than intensity in the determination of English stress. In Russian, vowel quality is directly and predictably related to stress placement, resulting in perceptual mergers of unstressed vowels. We synthesized pairs of Russian bisyllabic words with differing combinations of F0, duration, intensity, and vowel ferment frequency modifications one one syllable with the other syllable remaining untmodified. Five native speakers of Russian were asked to identify the randomly presented stimuli as fitting one of two possible grammatical frames. A nonsense-word pair also was synthesized and similarly presented. Results are discussed in terms of the relative effects of the four parameters and combinations thereof on stress perception in Russian. [Work supported in part by ONR.]
Synthetic deconvolution of explosive acoustic signals in colored noise
Authors: Dicus Ronald L.
Published: October 2005

A method is described for synthesizing acoustic signals from explosive charges and compensating for small variations of detonation depth. A single explosive source signal is measured under conditionsof optimum signal-to-noise ratio and depth compensated by the simple time expansion/contraction transformation f′(t) =f(ct), where c is specified by the bubble pulse period. A method is presented for precise determination of the bubble pulse period from the received signals. When corrected for acoustic spreading and absorption losses this signal is used as the input signal for deconvolution. The problem of noise generation in deconvolution is discussed and a filter for minimizing the effects of noise is employed based on least-squares linear estimation. Differences between synthetic and measured signal levels in one-third-octave bands from 31.5 to 3150 Hz averaged 0.2 dB with a standard deviation of 0.6 dB. In the deconvolved traces sharp spikes were obtained and bubble pulses removed. The methods described permit deconvolution of acoustic signals at low frequencies in colored noise and in situations where a satisfactory source signal cannot be measured.
Wheres and whyfores of preach seduction
Authors: Fromkin Victoria A.
Published: October 2005

Every model of speech production aims at describing and hopefully explaining how a message (idea, thought) is transformed through a succession of stages into an acoustic signal which “represents” it. We are far from understanding even the most basic aspects of this process which involves the relation between thought and language at one end and which ends with the neural commands to the vocal apparatus and the resulting acoustic signals. Speech error data provide some clues concerning the more abstract encoding mechanisms. Such data show the interaction of phonological, phonetic, syntactic, semantic, and lexical “levels.” They also reveal the effect of external influences (e.g., “He made hairlines” instead of “headlines” referring to a barber). Errors which can be accounted for in simple phonological terms may actually involve more complex mechanisms (e.g., “government testiphony” for “testimony”; “competed the MA exam” for “completed”). An analysis of such errors suggest that speech production be viewed as an interactive parallel process permitting linguistic and nonlinguistic interference with the intended message. [Research supported by NIH.]
Statistical characteristics of underwater ambient noise fields
Authors: Jobst W. J. , Adams S. L.
Published: October 2005

A rigorous study of the statistical characteristics of ambient noise fields is required for the design of signal processing equipment. In this paper. we present preliminary data on the basic structure of underwater acoustic ambient noise fields. The behavior of noise power as a function of time, frequency, and space has been analyzed for several sets of field data at a broad range of acoustic frequencies. Results of a runs test for independence of samples, Kolmogorov-Smirnov stationarity tests, and Kolmogorov-Smirnov goodness of fit tests are presented for narrow-band noise. New results describing the broad-band behavior of the ambient noise process are presented. [Research supported by Office of Naval Research. Code 222.]
Infrasonic sea noise at the Mid-Atlantic Ridge near 37 °N
Authors: McGrath J. R.
Published: October 2005

Underwater ambient noise spectra, spectrum levels, and statistics are described for data continuously recorded in the 5–32-Hz band for 176 h. These measurements were made using two ocean bottom seismographs located in 2478 m of water within the seismically active median valley of the Mid-Atlantic Ridge near 37 °N. Laboratory tests of the H-38 hydrophone show that flow noise levels developed by a 0.3 knot current—the maximum speed anticipated in the median valley—did not exceed the electronic noise level of the recording instrument. Over 500 underwater earthquakes were detected and epicenters were estimated to lie within about 20 km of the instruments. Seismic disturbances raised noise levels at least 20 dB across the acoustic band, varied in local magnitude from 1.2 to 2.5, persisted for as long as 2 min, and occurred on the average of 2.9 events/h. Sound pressure spectrum levels averaged over the entire recording period and compared to shipping noise curves proposed by Wenz and Urick infer that infrasonic and low-frequency noise are dominated by distant shipping traffic noise. [This work was sponsored by Naval Electronics Systems Command, Code 320.]
Seaquakes at the Mid-Atlantic Ridge near 37 °N
Authors: Francis T. J. G.
Published: October 2005

Joint acoustic and seismic observations have been made at the intersection of a fracture zone and the Mid-Atlantic Ridge near 37 °N over a period of several days. Over 500 seaquakes were detected; their epicenters were located by using S and P wave arrival times recorded by two ocean bottom seismometers. The analysis and discussion of seismic data, and their interpretation and application to a geophysical model of the region, indicates the rift valley to be an unusually low velocity region.
Haunted Arctic
Authors: Merklinger Harold M. , Morash H. Scott
Published: October 2005

Sunobuoys dropped at ten widely dispersed locations (500-mile radius) over a five-day period in the Canadian Arctic indicated the existence of a widespread acoustic phenomenon, presumably of biological origin. Several distinct types of sounds were heard. Cascades of linear-period FM pulses lasting approximately 45 sec and covering the frequency range 3000–300 Hz were heard at locations from Ungava Bay, through Foxe Basin to Barrow Strait. Such sounds are generally attributed to the bearded seal. Many other classes of sounds were also heard. Sounds of biological character were not heard in the Labrador Sea, or in southern Hudson Bay. A sample of the sound is played; comments are most welcome.
Sonar for generalized target description and its similarity to animal echolocation systems
Authors: Altes Richard A.
Published: October 2005

Range-distributed targets are often characterized arrays of point scatterers. This conceptualization corresponds to a target impulse response that is a sequence of impulses. A physically meaningful generalization of this description is obtained by modeling an impulse response in terms of pulse doublets, impulses, step functions, ramp functions, etc., i.e., as a superposition of delayed impulses and differentiated or integrated impulses. The resulting impulse response model resembles a spline function without continuity conditions. A sonar system for generalized target characterization is described; signals and receivers are specified for (1) optimum estimation of reflector parameters and (2) detection of a known target in clutter. The derived signals correspond closely with some of the waveforms that are used by dolphins and bats for echolocation. The corresponding echo analyzers are similar to some psychoacoustic models of the mammalian hearing system.
Auditory sensitivity of the House Finch (Carpodacus mexicanus) and the Field Sparrow (Spizella pusilla)
Authors: Dooling R. J. , Baylis J. R. , Zoloth S. R.
Published: October 2005

Using a behavioral audiometric technique previously developed for the parakeet [R.J. Dooling, J. Acoust. Soc. Am. 53, 1757–1758 (1973)], absolute auditory thresholds were obtained from several House Finches and Field Sparrows. Both species show a range of maximum sensitivity between 1.0 and 4.0 kHz. Below 2.0 kHz, sensitivity declines at the rate of about 15 dB/octave for the House Finch and about 10 dB/octave for the Field Sparrow. Above 2.0 kHz, sensitivity declines at the rate of about 30 dB/octave for both species. Both audibility curves show the characteristically avian pattern of a narrow range of maximum sensitivity and a high rate of rolloff in sensitivity at higher frequencies. The House Finch and the Field Sparrow are among those avian species in which selective vocal learning has been demonstrated. [Work supported by NSF.]
Evoked response audibility curve of the parakeet (Melopsittacus undulatus)
Authors: Dooling E. J. , Walsh J. K.
Published: October 2005

Auditory-evoked brain responses to tone bursts of different frequencies and intensities were recorded from surface electrodes on the skull of unanesthetized parakeets. Evoked response amplitude increased linearly with the log of stimulus intensity. Amplitude-intensity functions were computed using the method of least squares for three different amplitude measures of the evoked response waveform. Extrapolation of the amplitude-intensity functions at each frequency to the x intercept showed a close relation to the parakeets's auditory threshold as measured behaviorally. The best threshold estimates were obtained from the earlier components of the evoked response waveform with the average difference across frequency between evoked response threshold estimates and the species' audibility curve being less than 8 dB. Latency to the first positive peak of the evoked response waveform varies systematically as a function of the frequency and intensity of the stimulating tone.
Behavioral measures of the critical bandwidth in the chinchilla
Authors: Clark W. W. , Stebbins W. C. , Moody D. B.
Published: October 2005

A positive-reinforcement behavioral procedure was used to determine masked thresholds in the chinchilla. The critical bandwidth at 1 kHz was estimated in two ways. First, the threshold for a pure tone centered geometrically in bands of noise of constant spectrum level was determined. Thresholds increased with masker bandwidth up to the critical band, beyond which further increases in masker bandwidth produced no further increase in masked threshold. The critical band varied between 205 and 500 Hz in individual subjects. The second method was to measure the threshold of a tone centered between two bands of noise and to determine masked threshold as a function of spacing between maskers. The behavioral data for four chinchillas showed a slow decline in masked threshold as a function of spacing between maskers up to the critical bandwidth, and a very rapid decline as the spacing exceeded the critical bandwidth. The chinchilas showed critical bands at 1 kHz between 320 and 380 Hz. The two methods are compared and differences between obtained critical bandwidth are discussed. [Supported by grants from NSF and NIH.]
Auditory localization in primates as a function of stimulus bandwidth
Authors: Brown C. H. , Beecher M. D. , Moody D. B. , Stebbins W. C.
Published: October 2005

Monkeys (Macaca) were trained by operant conditioning techniques to report the minimum discriminable change in the locus of a sound in space. When a monkey made contact with the response key, a pulsed acoustic stimulus was presented from a standard location (zero degrees azimuth). After a variable number of pulses the stimulus changed position from the standard to one of several comparison locations. If the monkey reported this change by releasing the key, it received food as reinforcement. Thresholds for the minimum discriminable change in locus of a sound were determined by the method of constant stimuli. Testing was conducted under free-field conditions in an anechoic chamber. Monkeys were tested with noise bands of various bandwidths. The results indicate an inverse relation between threshold and bandwidth; as bandwidth is decreased the threshold for detection of a change in acoustic locus is increased. [This research was supported by a grant from NSF.]
Vibration and strain measurements on aluminum wheels used in rapid transit system cars
Authors: Nelson James T.
Published: October 2005

In December 1974, vibration measurements were performed on the two wheels of the most-forward axle of a standard BART A-type revenue car. Total radial wheel hub acceleration shocks of 120 g's and a fundamental frequency of 1500 Hz were measured witch two orthogonal radial accelerometers on each wheel. Lateral wheel hub acceleration transients of up to 80 g's and a fundamental frequency of 1700 Hz were also measured. Strain gauge data indicate steady-state inward and outward lateral forces of 10 000 lbs, caused by rails and restraining rails, respectively, existing over several wheel revolutions. Transient forces of duration on the order of 2 msec and longer, with magnitudes of up to 8000 lb inward or outward also were observed. The measurement techniques and instrumentation used in this study are also described, including the use of slip-rings and custom-made, axle-bore mounted accelerometer and strain gauge preamplifiers.
Noise exposure levels at CTA transit facilities
Authors: Wilson G. P.
Published: October 2005

The noise produced by CTA transit trains operations result in a wide degree of noise exposure levels for patrons. Measurements of the noise levels on station platforms and in the transit cars have indicated levels differing by an much as 10 to 15 dBA for similar operations along way structures of differing design. The highest noise levels are experienced on subway station platforms in tunnel stations which have concrete trackbed. In similar stations with ballasted trackbed the noise levels are typically 15 dBA lower. Operations in subways with concrete trackbed and ballasted trackbed show similar differences in car interior noise. Noise level observations for the CTA transit train operation are presented along with comparisons with results for new systems with modern facilities such as the BART system.
Normal-mode propagation of elastic waves in a fluid layer bounded by two different solid plates
Authors: Lauer G.
Published: October 2005

Some characteristics of normal mode propagation of guided ultrasonic waves in a fluid layer bounded by two different solid plates are presented. The phase velocities of the guided waves in several fluid-solid systems are calculated as a function of the frequency and the dispersion properties, which are strongly influenced by thickness and material of the two bounding plates, are compared. With a high speed schlieren arrangement the phase surfaces of the ultrasonic guided waves are visualized, and the wavelengths are measured and compared with the calculated ones.
Short-wavelength acoustic backscattering by a prolate spheroid
Authors: Lauchle G. C.
Published: October 2005

The backscattering of a plane acoustic wave from a rigid prolate spheroid of large fineness ratio (length-to-diameter ratio of 22) is investigated analytically. The backscattering cross section is computed with the use of large argument asymptotic expansions of spheroidal wave functions. It is shown that in the short-wavelength limit, a spheroid backscatters in the axial direction with nearly the same mean energy as a sphere whose radius equals the radius of curvature of the spheroid at the pole end. When the spheroid is positioned broadside to the incident wave, the backscattered mean energy is found to correspond to that backscattered from a sphere of diameter equal to the length of the spheroid. [Work supported by U.S. Naval Sea Systems Command.]
Acoustic diffraction by impedance edges
Authors: Hayek S. I.
Published: October 2005

A dual integral method was developed and applied to acoustic diffraction from edges. The surfaces of these edges have different impedances. Specifically, the acoustic diffraction by an edge which is pressure release on one surface and rigid on the other as well as edges with general complex surface impedances were solved. The solutions were found in closed form, in contrast with the solutions of G.D. Maluyzhinets and his colleagues. The analytic solution exhibits an explicit dependence of the diffracted field on the real component of specific surface admittance. The solution also shows that while the influence of each surface impedance extends to the acoustic field on both sides of an edge, each surface dominates the acoustic field in the half space on its side. [Work supported by NAVSEA.]
Speech intelligibility in a stationary multipath channel
Authors: Atkinson J. E. , Sergeant R. , LaCroix P.
Published: October 2005

The reception of speech transmitted through an acoustic channel such as the ocean is limited by multipath time-smearing. The purpose of the study was to obtain a quantitative measure of the effects of such distortions on speech intelligibility. No such measure presently exists. A linear time invariant channel was used to model the ocean's effects. For the present study, the impulse response was two ideal unit amplitude impulse functions separated in time by a variable delay τ (which ranged from 0 to 250 msec). This produces an echo τ msec after the original signal. Intelligibility results are presented for three types of speech material, Modified Rhyme Test monosyllables, revised CID sentences, and a novel triword test specially designed to measure the effects of multipath type of distortion. [This project was funded by NUSC IR fund.]
Function of strap muscles in speech
Authors: Erickson D. , Atkinson J. E.
Published: October 2005

Association of cricothyroid activity with high or rising fundamental frequency (f0) and strap activity with low or falling f0 in speech has been confirmed by numerous electromyographic experiments. The purpose of this study is to ascertain whether the role of the strap muscles in lowering f0 is analogous to that of the cricothyroid in raising f0. An electromyographic investigation of the sternohyoid and cricothyroid muscles was performed with speakers of English and Thai. It was found that there were indeed peaks of strap activity during low f0 and peaks of cricothyroid activity during high f0. However, examination of the timing of muscle activity with respect to f0 revealed that the cricothyroid differs from the strap muscles in that the cricothyroid begins to increase in activity prior to the onset of the f0 rise, whereas the increase of strap muscle activity begins after the onset of the f0 fall.
Ultrasonic detection of lateral pharyngeal wall movement
Authors: Ryan W. J. , Hawkins C. F.
Published: October 2005

Lateral pharyngeal wall (LPW) movement at the level of the velopharyngeal port was assessed with pulsed ultrasound. Data were collected for five normal talkers producing all combinations of the vowels /a/ and /i/ and consonants /p, t, k, s, m, n/ in a VCVCV context. Results indicated that while ultrasonic techniques posses the potential for the measurement of LPW motion, a number of problems must be solved before ultrasound surpasses current methods of studying velopharyngeal function and velopharyngeal incompetence. Specific difficulties associated with the quantitative search and location of the LPW, interpretation of multilayer returns, and intersubject variability will be illustrated and discussed.
Control of fundamental frequency, intensity, and register of phonation
Authors: Baer Thomas , Gay Thomas , Niimi Seiji
Published: October 2005

Electromyographic activity of several intrinsic and extrinsic laryngeal muscles was recorded simultaneously with subglottal pressure as untrained singers produced systematic changes in fundamental frequency (F0), intensity, and register of phonation. Cricothyroid-muscle activity was most consistently related to F0 over most of the range of F0, although the activity of several other muscles was also related to F0. Vocalis-muscle activity was most directly related to differences between the chest and falsetto registers. Subglottal pressure varied consistently with changes in vocal intensity. Activity of the extrinsic muscles was correlated with F0 change at both the high and low extremes of the chest-voice range. For at least one subject, the extrinsic muscles seemed to be solely responsible for varying F0 at its low extreme. The activity of muscles not directly associated with the larynx also changed systematically with F0 at the extremes. [This research was supported by NIH grants T22 DE00202 and DE01774.]
Initial and final phoneme confusions under reverberation
Authors: Gelfand S. A.
Published: October 2005

Initial and final consonant recognition confusions were investigated under reverberation times (RTs) of 0 to 3 sec. Mean recognition scores decreased with RT in both phoneme positions, but considerably more for final consonants. Initial phoneme confusion matrices were minimally affected by reverberation, with most errors being pure place confusions (/ptk/, /bdg/, /mn/, etc. ). Other initial confusions were randomly distributed, except for some nasals for voiced fricatives at 1-sec RT. Final consonant confusions at 0-sec RT also fell into place groupings, with other confusions randomly distributed. Under reverberation, however, while many final confusions were within place groups, several confusion patterns developed. Most frequently, these were substitutions of nasals for other phonemes. Voiceless fricatives were often perceived as voiceless stops at 1–3 sec RTs. At 3-sec RT, voiced stops were often substituted in place of other phonemes. Alveolars (/tdn/) accounted for the greatest number of confusion responses. Resistance to reverberation distortion differed between initial and final consonants and between RTs. Initial phoneme groups were similar at 1-sec RT, but the nasals and liquids were most susceptable to distortion at longer RTs. Among final phonemes, nasals and voiceless stops were the most robust, while fricatives were most susceptable to distortion. A basis for the confusion matrices under reverberation is suggested, and the data are compared with findings under noise, filtering, and other types of distortion. [Supported by VA.]
Relationship of intelligibility and subjective quality of digitally coded speech
Authors: Goodman David J. , Goodman Janet S. , Chen Mun
Published: October 2005

An experiment has been performed to investigate perceptual effects of digital encoding of speech. The aim was to gain information about the influence on intelligibility and subjective quality of three distortions that arise in analog-to-digital conversion: bandwidth reduction (B), peak clipping (C), and amplitude quantization (Q). Allowing two levels of each distortion, we produced eight encoders encompassing all possible combinations of B, C, and Q. By means of a consonant recognition rhyme test and a five-point opinion scale, 12 subjects provided intelligility and subjective quality data about each encoder. The results show that it is not always possible to predict the effects of multiple distortions from information about the effects of individual distortions and that the distortions influence intelligibility and subjective quality differently. For example, with respect to consonant recognition, Q and C reinforce one another; occurring together they cause more recognition errors than the sum of the errors caused by the two distortions occurring individually. On the other hand, the effects of Q and C on subjective quality are essentially additive. Of the three distortions, B has the most serious effect on intelligibility while C has the strongest influence on listener opinions.
Fret positions and string parameters for fretted stringed instruments
Authors: Houtsma Adrianus J. M.
Published: October 2005

A serious problem with exact intonation on most fretted string instruments is caused by the fact that each string is used to produce many notes, undergoing changes in effective length and in tension, and that one and the same fret is used to stop more than one string. To compensate for the increased tension when a string is stopped, the effective string length must always be a little larger than what one would expect from an inversely proportional relation to pitch. The optimum amount of compensation, however, is usually not the same for each string but depends on action height, string tension, and string elasticity. Optimum compensations were computed for nylon and steel guitar strings and results were compared with both a simple logarithmic fret layout and the more traditional “rule of 18.” Fretboard and string designs, securing exact intonation over the entire range of the instrument, are discussed. [Work supported by a grant from Norlin Music, Inc.]
Modes of vibration of tuned bars in percussion instruments
Authors: Rose Calvin , Rossing Thomas D.
Published: October 2005

The modes of vibration and sound spectra of tuned marimba, xylophone and vibraphone bars have been studied. The modes of vibration are determined by driving the burs electromagnetically, whereas the spectra are determined with a real-time spectrum analyzer while striking the bars in the conventional manner. The tuning of bars by undercutting is discussed.
Analysis and synthesis of bass drum tones
Authors: Fletcher Harvey , Bassett Irvin G.
Published: October 2005

Tones from a bass drum were recorded and played repeatedly through a 3-Hz bandpass filter. With each pass, the center frequency of the filter was increased 1 Hz. From this analysis the frequency, intensity, and decay rates of the most prominent components of the tone were determined. A reasonably close relationship was found to exist between these components and the ones predicted from the Bessel functions for a stretched membrane. Up to 200 components have been identified in this manner. These components vary in intensity according to where and how hard the drum is struck. The frequency of the fundamental decreases as the amplitude of vibration of the membrane decreases, finally approaching a constant at low amplitudes. Each of the components has a changing frequency that remains proportional to that of the fundamental. Synthetic drum tones were computed by adding a series of sine waves with frequencies, amplitudes, and decay rates taken from the analysis. Tones thus synthesized were compared with the recording of the real tones. A listening test was performed using 25 subjects. Each was presented a series of 30 tones consisting of three real and three synthetic sounds repeated five times in random sequence. The subjects were asked to decide whether each tone seemed real or synthetic. Overall results for the 25 subjects tested were 56% right.
How to make a slur
Authors: Mathews Max V. , Miller Joan E.
Published: October 2005

A study is described of some factors which lead to the perception of connectedness or slurring of a series of notes. These factors include the abruptness of the attack and decay of the amplitude envelope of the notes, the amount of silence between notes, and the pitch change between notes. Examples with various amounts of these factors were synthesized on the Groove computer and were judged as slurred or detached by musically experienced subjects. Silence, abrupt attack and decay, and abrupt pitch changes all produced a perception of detachment, the potency of these factors being in the order given. A maximum perception of slurring was obtained by having a slight time overlap between successive notes which had gradual attacks and decays.
Application of adaptive-modeling techniques to the development of human injury criteria
Authors: Muceiardi Anthony N.
Published: October 2005

The Department of Transportation (NHTSA) has initiated a program to apply adaptive modeling techniques to develop human injury criteria. In particular, the objective of this program is to develop quantitative measures of head injury as a function of kinematic parameters. Ancillary objectives include: (1) quantitatively assessing the information content of orthogonal accelerometer time-waveform curves relative to modeling one or more descriptors of head injury; (2) identifying the most discriminating subset of parameters derived from the various waveforms with respect to each of the head injury models; (3) establishing the existence of homogeneous subpopulations of similar experimental parametric data based on the best-found parameter subset: (4) determining the sensitivity of each of the head injury models to the input parameters; and, (5) formulating a head injury recovery control system that incorporates these head injury models in order to optimize the maintenance of life during the critical postaccident recovery period. The results of these various tasks will also provide important information regarding the relationship of head-mounted accelerometer waveform parameters and underlying neurophysiological damage. This talk documents the findings of this project and its impleations to other empirical models of human injury.
Case study of single industry in a residential neighborhood
Authors: Kleinschmidt K.
Published: October 2005

A cardboard carton manufacturer attempts to be a good neighbor in an otherwise residential section of a large city. The city's environmental noise department establishes that the lot line noise levels produced exceed the noise ordinance by as much as 25 dB in some actaves, takes the company to court, and obtains an injunction. A noise control engineer is hired to help the company reduce the noise levels in a manner that will please the city, the neighbors, and the company's owners. This case study describes the noise control measures and the legal steps that ultimately led to a satisfactory solution of the problem without closing down the plant.
Comparative aspects of frequency analysis
Authors: Fay R. R.
Published: October 2005

Major trends in the evolution of the inner ear are thought to be evident in a comparative analysis of structure among living vertebrates. To the extent that morphological features determine features for frequency analysis, then, we may study the evolution of frequency analysis through behavioral measures of discrimination and masking in a wide variety of living species. The existing behavioral data sample the frequency DL, the critical masking ratio (CR), and the critical bandwidth (CR) among certain mammals, fishes, and birds. The CR and the frequency DL are correlated but their ratios are not constants across species. The DLs and the CRs for fishes and birds fall within the mammalian range, suggesting that frequency resolution per se did not evolve progressively. However, resolution in hertz as a proportion of the total bandwidth over which analysis occurs does not appear to “progress” across a phyletic series from fishes to mammals. The fishes, and most amphibians and reptiles, hear best in the frequency range below 2 kHz, where a temporally coded analysis of waveform provides an adequate mechanism for frequency analysis. An extension of hearing bandwidth much beyond this range would not have increased the information-handling capacities of the organism unless the mechanical and neural mechanisms existed which could perform frequency analyses above the range already served by a temporal code. Once the “place principle” had established a means for maintaining a favorable signal-to-noise ratio (filtering) at high frequencies, the enormous expansion of hearing bandwidth characteristic of the mammals was free to take place.
Computer-based digital system for underwater acoustical measurements
Authors: Kodosky J. L. , Nowlin W. C. , Shorey J. L. , Truchard J. J.
Published: October 2005

A prototype underwater acoustic measurement system has been developed. The system uses a PDP-11 computer; it has the capability of measuring the usual parameters associated with underwater electroacoustical devices, such as transmitting and receiving sensitivities, high-level impedance, and beam patterns. A variety of signal-processing algorithms have been used with success. Included in these are single-point Fourier transforms, fast Fourier transform, rms measurements, and quadrature sampling. A special sampling scheme has been implemented so that an integral number of samples can be taken from each cycle of the signal being measured. This sampling scheme is especially useful for pulsed measurements. Accuracies and measurement computation time have been determined for several of these measurement algorithms. This measurement system was found to perform with greater flexibility than present analog systems, particularly with respect to display, recording, and processing of measurement data. One disadvantage of this measurement system is that additional manpower is required for programming and operation of the system over a conventional analog measurement system.
Reliability of digital data acquisition systems
Authors: Brittain F. H. , Marquard J. F.
Published: October 2005

Digital data acquisition systems have a great many advantages. However, since broadband fluctuating noise levels are recorded as a series of discrete digital samples, there are certain reliability problems in the digital recording process. It is possible to have invalid data recorded without its being detected. The primary sources of such potential problems of digital data acquisition systems are (1) intermittent system operation, (2) failure of system electrones, (3) unusual noise sources (one cannot listen to a digital tape), and (4) effects of adverse weather conditions. Techniques have been developed to detect these problems, thus increasing the reliability of the recorded data, and increasing confidence in results of the measurements. Application of several of these techniques to a B&K 181 Digital Recorder are described.
Long-range sensing of explosive source depths using cepstrum
Authors: Mitchell Stephen K. , Bedford Nancy R.
Published: October 2005

The acoustic signature of an underwater explosive source is a sensitive function of the source weight and depth of explosion; its power spectrum is characterized by a scalloped form. Even though the signal observed at long range is distorted due to propagation effects, the scalloped spectral structure is preserved; a characteristic period of the receiver signal, which is approximately the bubble-pulse period of the source, may be determined and used to measure the explosion depth. Examples of such measurements are presented in this paper. Signals from 1.8-lb charged detonated at nominal depths of 60 and 300 ft were examined. The bubble-pulse period of each source was determined onboard the source ship. The shots were received at ranges of 250–300 nm at one location and 650–700 nm at another. The depths as estimated at the two ranges, respectively, were distributed about the onboard measurements with standard deviations of 0.7 and 1.3 ft for the 60-ft sources and approximately 2.0 and 5.0 ft for the 300-ft sources. [Work sponsored by Office of Naval Research.]
Utilization of interactive computer graphics for acoustic source localization
Authors: Nadeau P. G. , Higgins K. M.
Published: October 2005

Oceanographic studies as well as Naval objectives frequently require one to localize acoustic emitters (targets) in three dimensions within the ocean medium. This series of display formats depict several ways in which interactive graphics techniques, including the use of color, can be of aid in the accomplishment of this task. In each case, the operator is provided with visual feed-back as to the sensitivity of results obtained from the observed data. The display formats along with the interactive technique chosen for discussion include the following figures: (1) range and depth estimation based on multipath time delays induced by the surface and bottom; (2) depth estimation based on available range inputs and a single boundary-induced time delay; (3) an interactive, bearings-only localization technique augmented with color as a visual coding method. The color of the “bearing difference” curves reflect the solution quality in a probabilistic sense; (4) the technique depicted in (3) modified to provide simultaneous depth estimation; and (5) a color-coded sound wave ray trace diagram which visually differentiates among the direct path region, the boundary-reflected insonified regions, and the shadow zones.
Installation of a rectangular test section for acoustic water tunnel studies of flow-induced noise
Authors: Schloemer H. H.
Published: October 2005

A second leg was added to the existing pump-driven, continuous-flow, closed-loop acoustic water tunnel at NUSC to provide a capability for measuring flow-induced noise effects and the effects of surface roughness, proturberances, depressions, and pressure gradients on turbulent boundary-layer wall-pressure fluctuations. The leg consists of a rectangular test section (4 in. high at the entrance and 4.5 in. high at the exit, with a constant width of 12 in. over a length of 90 in. and appropriate associated components to ensure proper hydrodynamic and acoustic conditions in the test section. This article briefly describes the design and construction of the new test section and related components and the results of hydrodynamic and acoustic measurements made to verify that the section was operating properly. The acoustic frequencies and flow velocities for which smooth wall, zero-pressure-gradient turbulent boundary-layer pressure fluctuation measurements are valid have been determined by using small flush-mounted hydrophones. At the maximum operating velocity of 18 feet per second (10.7 knots), the frequency band for valid pressure-fluctuation spectral-density measurements is 40–2500 Hz.
Flow noise response of gradient hydrophones
Authors: Keller B. D.
Published: October 2005

The flow noise response of several types of gradient hydrophones is investigated by comparing experiment with model results. Several effects are given detailed investigation, such as differentiating between noise that is conducted directly from the flow and noise that is cause by case acceleration. Models are derived for gradient hydrophones with added flow screens, and these models are used to predict the operational effects of several types of flow screens.z
Exploratory investigation of cavitation noise
Authors: Arndt R. E. A.
Published: October 2005

As part of an in-depth study of cavitation scale effects, the acoustic signature from cavitation in the wake of a sharp-edged disk was investigated. The study was made with four sharp edged disks ranging in diameter from 2 to 16 cm with a Reynolds number range of about 8×104 to 2×106. Measurements were made in both a large water tunnel and a depressurized towing tank, representing the first time that comparative cavitation data in both a water tunnel and a tow tank are available in the Western literature. The spectrum of the noise is correlated with measurements of upstream nuclei content utilizing a laser scattering technique developed by Keller. The results show that the spectrum is strongly related to the upstream pressure, the nuclei content, and whether the liquid is supersaturated at the local static pressure. The pressure field in the wake, which induces the cavitation, is strongly dependent on the characteristics of the boundary layer on the face of the disk. [Work supported by the Netherlands Ship Model Basin and the Netherlands Navy.]
Dyadic synthesis of medial consonants in CVCV utterances
Authors: Nakatani Lloyd H. , Wischmeyer M. Kay
Published: October 2005

Dyads representing the transitions between adjacent phonemes can serve as units for speech synthesis. But since the transition between two phonemes depends on their context, a a single dyad cannot represent the appropriate transition in all context where the two phonemes may occur. In particular, Ohman's work suggests that the transitions in V1C and CV2 dyads excised from V1CV1 and V2CV2, respectively, may be inappropriate for the synthesis of V1CV2 when V1 ≠ V2. The medial consonant in CV1CV2 utterances was synthesized from such dyads to see if inappropriate transitions caused perceptible degradations, and also to determine how easily various consonants could be synthesized. The vowels /i,æ,u/ and the consonants /b, d, g, k, m, n, v, s, z, dȝ, l, r, w, j/ were used. Original and synthesized versions were played in pairs to listeners who stated which version they preferred in each pair. The results showed that (1) the perceptibility of inappropriate transitions was minimal and (2) all consonants were synthesized well. The quality of the synthesized speech supports dyadic synthesis.