bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of acoustic input impedance of an excised canine pulmonary system by transient excitation
Authors: Fredberg J. J. , Jackson A. C. , Dawson S. V.
Published: October 2005

The acoustic input impedance of a freshly excised canine lung was measured in the frequency range of 80 to 10 000 Hz. The pulmonary system was coupled at the trachea to a long acoustic transmission line which was excited at the distal end by an electrical spark discharge. The waveforms incident upon and reflected from the pulmonary system were digitized and used to determine the complex reflection coefficient and input impedance of the termination. At 300 Hz, a zero of the reactance and peak in the resistance occurs. Other system resonances are observed below 1000 Hz. Above 1000 Hz. the input impedance is primarily resistive. Decrease in lung volume systematically reduces the peaks in the resistance and reactance but alters the resonant frequencies only slightly. To aid in interpreting this data the airways of the lung were modelled as a nonuniform transmission line with reactive walls. This model includes the effects of rapid flare of airway cross sectional area, mechanical properties of the wall (mass, stiffness, and damping), and thermal and viscous boundary losses. [Work supported by National Heart and Lung Institute.]
High data predictive coders
Authors: Golberg A. J.
Published: October 2005

This paper describes how adaptive predictive coding techniques can be used to improve voice transmission at data rates of 9.6 and 16 Kbps. With the use of multilevel quantizers, these coders do not perceptually degrade voice transmission over the original when operated at 16 Kbps if the coder employs a 2500-Hz bandwidth. Performance will be demonstrated by signal-to-noise measurements and by audio recordings.
Computer-controlled x-ray study of Japanese consonants and vowels—a preliminary report
Authors: Kiritani S. , Fujimura O.
Published: October 2005

A set of data of Japanese CV syllables has been obtained for two native speakers of the Tokyo dialect by use of the computer-controlled x-ray microbeam system [J. Acoust. Soc. Am. 57, 1516–1520 (1975)]. The material included /pV tV kV sV bV dV gV zV/, where V is /i, e, a, o or u/, repeated in immediate succession. For one subject, five pellets were placed on the tongue surface in the midsagittal plane, with another pellet on a lower tooth. The six pellets were tracked at a rate of 120 sample sets per second. The data are being analyzed, and tentative conclusions include: (1) the blade of the tongue (in reference to flesh points) is more advanced for [e] than for [i], (2) k-g and t-d oppositions reveal different tongue gestures, (3) for dental consonants, the tongue body makes a characteristic forward movement, and these movements are slower for fricatives than for stops. A slow motion picture of the movements of the pellets will be demonstrated.
Feedback of intraoral air pressure?
Authors: Perkell J. S.
Published: October 2005

In a recent feedback experiment [A.H.B. Putnam and T. Shipp, J. Acoust. Soc. Am. 57, S70 (1975)], an unexpected, partial venting of intraoral air pressure during intervocalic /p/ production was reported to result in no measurable change in the duration of laryngeal (PCA) EMG activity. However, other measurements of articulatory activity and interference with alternate, possibly redundant feedback pathways were not included. An apparatus has been designed to implement an extension of the pressure-venting paradigm. A translabial tube is connected via a voice-actuated, solenoid-operated valve in series with a manually operated ball valve to a vacuum source. Depending on whether or not the ball valve is open, the oral cavity is connected with the vacuum source during intervocalic /p/, producing a pressure decrease rather than an increase. The use of this device both with and without labial sensory anesthesia should result in four different “feedback” conditions. Careful comparison of several measures of articulatory activity in response to the four conditions might further indicate whether or not intraoral air pressure may be used as feedback information for coordination of speech motor gestures. Preliminary results will be discussed.
Perceived pitch of vibrato tones
Authors: Shonle John I.
Published: October 2005

A new measurement of the perceived pitch of tones with vibrato has been made using the method of adjustment with five subjects. Adjustments were made for the following conditions with sine wave signals: 440.0 Hz unmodulated, 220.0 Hz with a range of ±6.4 Hz, 440.0±6.4 Hz, 440.0±12.9 Hz, 440.0±26.2 Hz, and 880.0±25.8 Hz with a modulation rate of 6 Hz. In addition, a square wave signal of 440.0±12.9 Hz was used. The averages of the settings minus the central frequencies and the standard deviations of the distributions obtained are −1.9±4.4 ¢, −0.3±8.0 ¢, −1.4±5.8 ¢, −2.9±8.0 ¢, −6.4±14.2 ¢, −0.5±11.7 ¢, and −5.1±10.6 ¢, for the condition in the same order as given above. If the differences for the unmodulated signal are treated as constant errors, then the following corrected average values are obtained for the 440-Hz sine waves: 0.5±4.9 ¢, −1.1±7.0 ¢, and −4.6±13.4 ¢, respectively. These corrected values are compatible with the geometric means and not the arithmetic means in the latter two cases. In addition, two subjects were tested at modulation rates of 4 and 8 Hz for the 440.0±12.9 Hz case with no statistically significant variations from the case of the 6-Hz rate.
Perception of interleaved melodies with different timbres
Authors: Zagorski M. A.
Published: October 2005

The ability of subjects to make same-different judgments of target melodies interleaved with sinusoidal “masking” melodies with various partials present or absent in the target was investigated. The melodies were stochastically generated with identical melodic centers, limited pitch extent, and no intervals of greater than three semitones. Clearly, the presence of the first, second, or first and second greatly facilitated the subjects performance. This is probably not due to the timbral distinctiveness of the notes in the target, however, because the presence or absence of the fundamental in the target had virtually no effect. This allows the interpretation that subjects ignore the critical band containing the fundamental and attend only to the upper partials. This is consistent with Dowling's finding that the perception of interleaved melodies is greatly enhanced if their pitch separations are approximately a critical band or more [W.J. Dowling, Cognitive Psych. 5, 322–337 (1973)]. [This work was supported by the National Research Council of Canada.]
Study of subglottal air pressure in Hindi stop consonants
Authors: Dixit R. Prakash , Shipp Thomas
Published: October 2005

This study examines Ps variations in Hindi bilabial stops. These stops were produced in prestressed and poststressed positions in CVCV, VCV, VC, and CV utterances, where V was either /a/ or /i/. The results show: (1) At closure Ps values are appreciably higher for poststressed than prestressed stops in comparable environments; at release, values are only slightly higher for poststressed than prestressed stops in all cases in the aspirated category and in 50% of the cases in the unaspirated category. (2) In poststressed position, Ps values, at release, are usually appreciably higher for aspirated than for unaspirated stops; in prestressed position, at release, such variations in Ps values are unsystematic. (3) The pattern of Ps values for aspirated versus unaspirated stops at closure, is also unsystematic in both prestressed and poststressed environments. (4) No systematic patterns of Ps values, emerge for voiced versus unvoiced stops in prestressed or poststressed positions at closure or release. (5) For aspirated stops, a drop in Ps (of the degree of 1 cm H2O for unvoiced and 0.5 cm H2O for voiced aspirates) occurs after consonantal release during the aspiratory period. The results of this study are discussed in relation to results of other studies.
Noise control design guide for the food-processing industry
Authors: Kugler B. Andrew , Klick David C.
Published: October 2005

Noise problems in food-processing plants have evolved naturally, chiefly due to progressive mechanization and automation in the industry. As a result, plant operators have, for a long time, been concerned with excessive personnel noise exposure and individually have attempted to introduce noise control wherever possible. However, no industry-wide effort to the solution of common noise problems was attempted in the past. The control of equipment noise in this industry is made especially difficult due to the strict standards of sanitation that must be preserved throughout each plant. This paper presents a brief overview of an industry-wide program, sponsored by the Northwest Food Processors Association, which resulted in the development of controls for six major noise sources in the industry. The results are contained in a design guide which takes the process engineer through the basic steps necessary to measure, evaluate and incorporate the proper noise control measures that will provide compliance with the OSHA regulations. The solutions presented include the following equipment or processes: (1) vibrating conveyors, (2) blanchers, (3) positive and negative air systems, (4) high pressure air and steam, (5) can handling systems, and (6) seamers. Typical solutions are presented and described.
Aerodynamic pressures on vortex-shedding struts
Authors: Blake W. K.
Published: October 2005

New measurements will be presented of the aerodynamic pressures induced at trailing edges of rigid struts. These pressures are generated with a sinuous time dependence when the wake of the strut is characterized by a von Karman vortex street. The variation of the surface pressure with upstream distance from the trailing edge is given for a series of edge configurations. These include varying ratios of trailing edge thickness to the thickness of the boundary layer which separates at the edge, as well as variations in the edge geometry. The mean-square pressures are found to depend on x−1, where x is the upstream distance from the edge, within ten edge-thicknesses of the edge. Spatial surveys of the disturbances in the wake provide intensity and length scales which reflect the shed vortex strength and structure and they therefore relate to the magnitudes of the pressures. A dimensional analyses is presented which specifies this relationship. The resulting dimensionless chordwise distribution of fluctuating pressure is shown to be given by an empirical function which is similar for all edges examined.
Installation and airspeed effects on jet shock-associated noise
Authors: von Glahn U. , Goodykoontz J.
Published: October 2005

Experimental acoustic data are presented to illustrate, at model scale, the effect of varying the nozzle-wing installation on jet shock associated noise, statically and with airspeed. The variation in installations included nozzle only, nozzle under the wing (with and without flaps deflected), and nozzle over the wing (unattached flow). The nozzles used were a conical and a six-tube mixer nozzle with a cold-flow nozzle pressure ratio of 2.1. A 33-cm diameter free jet was used to simulate airspeed. With the nozzle only, shock-wave noise dominated the spectra in the forward quadrant, while jet-mixing noise dominated in the rearward quadrant. Similar trends were observed when a wing (flaps retracted) was included. Shock noise was attenuated with an over-the-wing configuration and increased with an under-the-wing configuration (due to reflection from the wing surface). With increasing flap deflection (under-the-wing) configuration, the jet-flap interaction noise exceeded the shock noise and became dominant in both quadrants. The free-jet results showed that airspeed had no effect on shock noise. The free-jet noise data were corrected for convective amplification to approximate flight and comparisons between the various configurations are made.
Guidelines for the preparation of short illustrated technical talks
Authors: Hubbard H. H.
Published: October 2005

Practical suggestions are given for preparing short technical talks that are designed for maximum information exchange. The coordinated use of figures to complement the text is discussed, and rules for numbers and types of figures are proposed. The needs of the listener are stressed and examples are given of preferred combinations of text and figures, particularly from the listener's point of view. The problem of timing is emphasized and rules are proposed for estimating the presentation time of a given amount of material or conversely for fitting material into a given time slot. Suggestions for improving clarity and efficiency of effort are briefly reviewed.
Discharge patterns accompanying sustained activation of motor units in speech musculature
Authors: MacNeilage P. F. , Sussman H. M. , Powers Randall K.
Published: October 2005

Data is presented from speech and nonspeech muscles partially confirming the hypothesis that steadily firing motor units show two different discharge patterns depending on firing rate. The transition zone, characterized by rates intermediate between those showing the two patterns, represents a basic property of motor units which may allow inferences about other neurophysiological properties, and mechanical properties of the unit. Transition zones of speech muscles innervated by cranial nerves (Anterior belly of Digastric Genioglossus, Orbicularis Oris, Depressor Labii Inferioris) were relatively similar and occurred at mean interspike intervals ranging mostly from 40–65 msec. These zones were similar to that of a “nonspeech” cranial muscle (masseter) but at smaller intervals than in limb muscles, innervated by spinal nerve (Biceps 80 msec, Rectus Femoris 85–95 msec). When two units fired together, the “gain” of the unit recruited second (i.e., the relative change of firing rate with input change) was virtually always greater. This difference was at least partly due to the relative responsiveness of the controlling motoneurons themselves, rather than to differences in amount of input to them. [Work supported by NSF.]
Variations in the normal male glottal wave
Authors: Fisher W. M. , Monsen R. B. , Engebretson A. M.
Published: October 2005

Observations of glottal sound waves were made with a reflectionless tube, improved in design from our previous report [J. Acoust. Soc. Am. 56, S61 (A) 1974]. Six adult male subjects phonated into the tube and recordings were made directly onto a digital-computer magnetic disk. The subjects phonated in a variety of modes: normal, loud, and soft voices; rising and falling intonation; stressed and unstressed syllables; and falsetto and creaky voice. A computer system calculated rms intensity, F0, and Fourier spectra of selected glottal periods and fitted polynomials in log(f) to the intensity spectra. Analysis of the data shows (1) a typical intensity spectrum fall-off steeper than −12 dB/octave, although a constant decibel/octave curve is not a particularly good approximation; (2) a typical phase angle difference between the first and second harmonics of about 180° (3) systematic variation of waveshape, intensity and phase spectra with F0 and rms intensity. Data presented in this paper can be used as a benchmark for study of abnormal phonation in addition to suggesting types of variation of the giottal source whose medeling could make synthetic speech more natural. [Supported by NINDS Grant NS 03856.]
Physics of vibrators
Authors: Skudrzyk E. J.
Published: October 2005

A vibrator can be represented by an infinite number of series resonance circuits in parallel. Circuit theory is an aid to the understanding of the behavior of complex vibrators and to the simplification of existing theories. If the mode density is constant, then the geometric mean between the resonance peaks and the antiresonance minima is determined (with an accuracy of 8%) by contributions of only the two modes whose frequencies are closest to the frequency of the force. This fact also makes it possible to generalize the theory for situations where the mode density varies discontinuously. The basic variable is a characteristic velocity that propagates through the vibrator and is reflected at its boundaries. This velocity—a simple function of the mode density and the mode masses—represents the geometric mean line through the frequency curve of the vibration velocity. The complex fluctuations in the frequency response of vibrators for points not coincident with the driven point, and the effect of ribs, attachment, and structural discontinuities can be easily understood on the basis of the characteristic velocity. [Work supported by ONR.]
Natural frequencies of elastically supported orthotropic rectangular plates
Authors: Magrab Edward B.
Published: October 2005

An expression is obtained from which the natural frequencies of a rectangular orthotropic plate, under any combination of boundary conditions of simply supported, elastically supported, or clamped. The Mindlin-Timoshenko theory, which includes the effects of transverse shear and rotary inertia, is used to describe the plate motion. The solution is obtained with an extension of the Galerkin procedure previously developed, in part, by the author. Comparison of results with the limited results of previous investigations is excellent. Numerous data are presented for the lowest natural frequencies of rectangular and square plates for boundary conditions on all four edges that vary continuously from simply supported to clamped, and for various combinations of length-to-thickness ratios.
Modification of panel response by a rib
Authors: Tucker A. J. , Vogel W. H. , Maidanik G.
Published: October 2005

The response of a fluid loaded, single ribbed panel simulated by a membrane is developed. The response is determined for two extreme types of excitation; namely, a localized excitation generated by a line force and an extended excitation generated by a single wave. For each of these cases the response of the ribbed panel is proportional to that of the unribbed panel, where the factor of proportionality consists of two terms. The first term is unity, and therefore the second term completely describes the modification of the response caused by the rib. The second term, in turn, consists of two factors. The first of which describes the modification of the response caused by the finite impedance of the rib; this factor becomes unity when the rib is assumed to be hard (i.e., fixed). The remaining factor describes the modification of the response when the rib is hard. The deviation of the first factor from unity when the rib is not bard (i.e., the extent to which the assumption is valid) is discussed.
Acoustic link reduction by digital processing
Authors: Gibson John R. , Arndt Horst
Published: October 2005

The work described in this paper is concerned with the digital simulation at Bell-Northern Research, Ottawa, of the various acoustic transmission paths between a loudspeaker and a microphone in a room. There are a number of possible applications for this work in the telecommunications industry relating to speaker phones and teleconferencing. A reasonably accurate simulation has been found to produce a reduction in signal level following the microphone of the order of 20 dB for signals which originate from the loudspeaker. Other signals originating in the room pass through the system with no effect. The voice switch has been a necessary but undesirable part of the majority of speaker phones and teleconferencing systems. Its function is to permit adequate audio gains while preventing the oscillations which would normally occur in a two-way conversation using loudspeakers and microphones. The voice switch effectively allows only one-way transmission at any time. It is generally found that the voice switch wfil respond to background noise and other spurious sound souroes as well as to speech and in some applications this action is quite undesirable. The simulation system, on the other hand, can allow in excess of 20 dB of additional gain before oscillations would occur and in a suitably benign acoustic environment, this could be sufficient to dispense with the voice switch altogether. Further applications of this work in telecommunications include the reduction of ambient noise for the benefit of the far-end user in either bandset of hands-free operation. This would be a useful facility for persons wishing to communicate in high ambient noise conditions, such as in or around large pieces of equipment, or aircraft, etc.
High-power acoustic transmitter arrays
Authors: Priestley Tant , Hunter Del
Published: October 2005

A high-power acoustic transmitter with design goals of producing a narrow bean (≈5° half angle to 3-dB points), minimum side lobes (40 to 50 dB down) and high acoustic power (≈500 acoustic watts) was producted by NOAA's Wave Propagation Laboratories for use in the FAA sponsored wind shear measuring system. The antenna was required to operate under all weather conditions and to produce a 1250-Hz pure tone for a duration of 0.1 to 0.5 sec with repetition rates of 6 to 8 sec. The transmitter design consists of an amplitude-shaded array made up of 144 omnidirectional elements mounted in a 12×12 configuration on a fiat reflecting plane. Results of acoustical impedance measurements performed on a set of apertures which simulated the element openings and measurements aimed at compensating for element-to-element interaction are presented along with beam patterns from a full-scale antenna.
Community response to structure-shaking impulsive-type noises
Authors: Johnson Daniel L. , Schomer Paul D.
Published: October 2005

There is a large class of impulsive-type noises such as quarry blasts, artillery fire, sonic booms, etc., that are not only directly perceived by individuals, but can also result in noticeable vibration of structures and buildings. This vibration in combination with the acoustic stimulus can cause a community response that would not necessarily correlate with the descriptor used for acoustic responses such as NEF or Ldn. Thus a modified environmental descriptor appears to be required for this class of impulses. Various governmental agencies need this descriptor for prediction of individual and community response, land use planning, and preparation of environmental impact statements. Different methodologies for assessing this class of noise will be discussed and a unified criterion using a common descriptor is proposed. In this unified criterion, community response data, predominantely from sonic boom studies, form the basis of the cause and effect relationships. The “no health effects”level with respect to public health and welfare is chosen to correspond in community response to an Ldn of 55 dB.
Impact noise test method using a modified hammer machine
Authors: Schultz Theodore J.
Published: October 2005

The current national (ASTM E-492) and international (ISO-R140/R717) impact method involves the use of a standard hammer machine for evaluating the impact noise isolation of floor/ceiling structure. The method has been severely criticized on the ground that ratings based on the test data correlate poorly with the subjective judgments of people listening to real-life impacts on the same floors. An alternative test method is proposed that uses a modified hammer machine whose internal impedance, intensity of impact and striking frequency simulate those of real footfalls; the new method involves reading the "peak" (i.e., short-term rms) impact sound pressure levels in the receiving room, replacing the current practice of reading long-term rms levels. No normalization for the sound absorption of the receiving room is required. Since the peak impact levels, particularly for floors with good impact isolation, are much higher than the long-term rms levels usually measured, the interference of background noise is much less for the new method. These proposed changes, based on recent studies, are expected to lead to better correlation between the test data and subjective judgments of floors. On an experimental basis, it is proposed that the range of measurement be extended down to 40 Hz, because of the certainty that low-frequency components are significant in the subjective evaluation of wood joist floors and the probability that peak levels are less susceptible to the problems of standing waves and lack of diffuseness than rms levels.
Multipath expansion for computing acoustic propagation loss in horizontally stratified media
Authors: Weinberg H.
Published: October 2005

The multipath expansion for horizontally stratified media is a generalization of acoustic ray tracing that is, in theory, exact and, in practice, accurate at the sonar frequencies. A variation of the expansion includes normal modelike terms along with the multipaths. Computed propagation loss for a shadow zone to the right of a caustic shows the well-known exponential decay. However, the acoustic pressure appears to increase when the shadow zone is at the left of the caustic, at least in the example studied. Finally, computed propagation loss in the Pacific Ocean is compared with a wave model at 50, 500, and 2000 Hz. The multipath expansion is as accurate as the wave model, but far more practical.
Considerations in the incorporation of stochastic input in a ray-tracing model
Authors: Barnes A. E. , Solomon L. P.
Published: October 2005

Although the wave equation has been considered in a random media, ray tracing in a stochastic environment has been essentially neglected. This presentation examines the factors involved in the development of such a ray trace model. This includes the structure and properties of the random fields (and the consequent theoretical problems), the choice of a stochastic model and, most importantly, the determination of the parameters of the stochastic mede1. It is shown that optimal values of the process parameters may be determined using a relatively simple algorithm.
Signal travel time in long-range propagation
Authors: Mitchell Stephen K. , Hampton Loyd D.
Published: October 2005

The times from detonation of a large number of explosive sources to the detection of their acoustic signals at long distances in the Northeast Pacific and North Atlantic oceans have been measured. The sound velocity structure at the former location shows a single, well-defined minimum at approximately 800 m, while at the latter there are minima at approximately 200 and 1200 m. Ray-tracing computations show that the signal travel time as a function of range will have periodic fluctuations about a linear function. The magnitude of the fluctuations is approximately the spacing between the first two multipath arrivals, which is 1 sec for the Pacific and 0.5 sec for the Atlantic. The measurements exhibit the phenomena predicted by the timing computations.
Ocean turbulence with application to acoustic coherence
Authors: Del Balzo D. R. , Moseley W. B.
Published: October 2005

The coherence of long range underwater acoustic signals is strongly influenced by the complex transmission medium, in particular, by the power in the fluctuating temperature field. A statistical description of horizontal thermal microstructure in anisotropic turbulence is developed for application with an existing acoustic propagation theory. A two-term power law representation for buoyancy and convective forces is applicable for wavenumbers greater than those of the internal-wavefield, but less than those in the dissipation range. The model predicts a temperature power density spectrum which decays as −53 and −3 with wavenumber in the convective and buoyancy ranges, respectively. The power in the two ranges (i.e., the strength of the turbulence) is a function of depth and depends on the total rate of energy dissipation, the total rate of dissipation of temperature variance, and the Brunt-Väisälä frequency. Companion experimental data from 54 long horizontal tows at depths between 97.5 and 1454 m at two widely separated stations in the Bermuda area of the North Atlantic verify the theoretical predictions. The environmental effects on the theoretical acoustic correlation length are examined for limiting values of measured strengths of turbulence.
Propagation through an anisotropic random medium: An integro-differential formulation
Authors: Beran M. J. , McCoy J. J.
Published: October 2005

In a previous paper [J. Math. Phys. 15, 1901 (1975)], we derived an equation governing the mutual coherence function {Γ̂} of an initial plane-wave signal propagating in an anisotropic random medium. In Eq. (49) of that paper we made a strong narrow-angle approximation which allowed us to derive an ordinary differential equation for {Γ̂}. Here we derive an integro-differential equation for {Γ̂} in which this approximation is not made. We show that for the horizontal scattering cases considered in the previous paper the approximation is valid. Finally, we derive the equation governing the field coherence function {Γ̂I}={p(τ1)p(ψ2)} and discuss the implications of the assumption of Gaussian statistics for intensity fluctuations.
Photophone performance
Authors: Nelson D. F. , Wecht K. W. , Kleinman D. A.
Published: October 2005

A photophone consisting of a light guiding fiber, an absorption cell containing charred cotton suspended in air, an exponentially tapered tube, and a standard earpiece volume has been made and tested. The pressure in the earpiece versus the frequency in the 300 to 3300 Hz telephone band for a given optical power input agrees well with the theory of the preceding paper. We conclude that the charred-cotton-suspended-in-air can be treated simply as light-absorbing air. Measurements were also made on a photophone which included an air column equalizer to resonate with the absorption cell in order to flatten the frequency response. The high-frequency (1500 to 3300 Hz) response was enhanced as expected though not quite as much as predicted.
Measurements of the precedence effect
Authors: Zurek P. M. , Leshowitz B.
Published: October 2005

Interaural time and amplitude discrimination tasks were employed to assess the relative influence of direct and echoed sound in determining localization. Using headphones, a brief noise burst was presented binaurally, followed after a time, ISI, by a second binaural noise burst, an echo of the primary sound. Subjects were asked to detect interaural time or intensity differences on either the primary or the echo bursts in a forced-choice task. In general, time, and amplitude jnds are consistent with previous descriptions of the precedence effect. With primary and echo noise bursts at equal levels, interaural time and amplitude jnds for the second burst are considerably greater than those for the primary burst and reach a maximum with an ISI of about 1 msec. Attempts are made to relate the precedence effect to temporal masking phenomena and results from other discrimination tasks employing similar temporal paradigms.
What we listen for
Authors: Goldstein Louis
Published: October 2005

Most previous studies of the confusability of speech sounds have presented nonsense syllables in isolation, and have been limited to the confusability of consonants with other consonants or vowels with other vowels. In this experiment, the relative perceptual salience of the phonetic properties of longer speech segments was investigated. One-, two-, and three-syllable English words and phrases were excised from recordings of complete sentences. Words and phrases were chosen to include a large number of different stress patterns. All English (except [ɔι]) appeared in both stressed and unstressed syllables, and all English consonants (except [ŋ] and (ȝ]) occurred syllable-initially in stressed, unstressed, and reduced syllables. Word frequency was also controlled. Subjects listened to the excised segments and were asked to identify each one. Transcriptions of subjects' recorded responses were analyzed to determine subjects' errors. Errors were systematic and a hierarchy of relative perceptual salience of phonetic properties (eg. consonant vs vowel, stressed vs unstressed syllable) was determined. This hierarchy is more relevant to understanding how we extract acoustic information in normal speech perception than confusabllity studies using isolated syllables.
Vibration and shock limits for occupants in buildings
Authors: von Gierke H. E.
Published: October 2005

Many guidelines and limit curves with respect to acceptability and comfort of building vibration for occupants of various types of buildings have been proposed over the past 50 years but so far no national or international standard exists on this subject. The ISO Standard 2631–1974 “Guide for the evaluation of human exposure to whole body vibration” recommends limits generally applicable to whole-body vibration but makes no specific recommendations with respect to application and modification of these general guidelines to satisfy the occupants of various types of buildings. A proposed amendment to the ISO standard is discussed which recommends measurement procedures, frequency weighting curves and limit values for continuous or intermittent vibration for residential spaces, offices, workshops, and critical spaces such as hospital operating rooms or research laboratories.
Acoustical environment in open plan office—the state of the art
Authors: Harris D. A.
Published: October 2005

ASTM E-33.04C Subcommittee on Environmental Acoustics, Applications Subcommittee Task Force on Open Office Acoustics has prepared a publication titled, “Acoustical Environment in Open Plan Office—The State of the Art.” The purpose is to “assemble and explain responsible references to the state of the art.” Principles gathered to prepare this paper will be used to develop “applicable ASTM Standards and Recommended Practices.” The paper deals with the “acoustics of an open plane office in a manner that will clarify the basic acoustical principles and help designers and architects to achieve an acceptable and flexible environment.” Items covered include the nature of the sound field, speech communication versus privacy, attainment of privacy, ceiling screen and masking sound effectiveness, testing, and design parameters. A summary of the paper will be presented.
Concorde noise and historic structures
Authors: Hershey Robert L. , Kevala Russ J. , Burns Sharon L.
Published: October 2005

The probability of failure of structural elements from vibration induced by noise from subsonic Concorde overflights was calculated for five historic sites near Dulles and Kennedy Airports. The structural elements investigated included windows, brick chimmeys, stone bridges, and plaster ceilings. Breakage probabilities were calculated using the response probability density function technique, which had been used in previous structural response studies for sonic boom and subsonic aircraft noise. The calculated breakage probabilities were generally less than 0.001 per year of Concorde operations. The only exceptions were some cracked windows at Sully Plantation, which were slated to be replaced anyway; these had a predicted breakage rate of once every five years. The failure rates of all elements were found to be considerably below those that would be expected just from exposure to the weather. [Work supported by Federal Aviation Administration.]
Effects of attention on single-unit activity in monkey auditory cortex
Authors: Benson D. A. , Goldstein M. H. , Hienz R. , Hocherman S.
Published: October 2005

Single-unit responses were recorded from the auditory cortex of rhesus monkeys while they responded to light or sound stimuli. The animals were rewarded with water for pressing a lever to the left for a noise burst or a left light and to the right for a tone burst or a right light. A light and sound stimulus was then presented simultaneously in four different combinations and in random order. Animals were conditioned to respond correctly (i.e., “attend”) to either the light or sound part of the combined stimulus. Responses of single units to sound stimuli were compared when the animal was not performing, attending the sound stimuli, and attending the light stimuli. Approximately 50% of the units showed behaviorally related increases or decreases in acoustically evoked activity. The number of units that showed a stronger response to acoustic stimuli when the light stimulus was attended equaled the number with stronger responses when the sound stimulus was attended. Regardless of the stimulus attended, most units responded more strongly when the light and sound stimuli both indicated the same direction of lever press. When contrasted to human performance in the same task, the monkeys' behavioral data suggest that the animals did not necessarily selectively attend one of the two stimulus modalities in performing the task. Preliminary results of this study were presented at the April 1974 meeting of the Acoustical Society [J. Acoust. Soc. Am. 55, S86(A) (1974)]. [Supported in part by NIH Grant No. NS-05143.]
Effect of auditory cortex ablation on sound localization in the monkey
Authors: Heffner H. , Masterton B.
Published: October 2005

Rhesus monkeys with and without primary auditory cortex were tested for their ability to localize the source of a single brief click by two different techniques. The first technique required the monkeys to indicate the direction of the source of a sound by pressing a lever on either its right or left side in response to a click emanating from loudspeakers on either its right or left side. The second technique required the monkey to locate the sound source by walking to one of two loudspeakers which had emitted a click. It was found that monkeys deprived of primary auditory cortex can indicate the direction of a sound source, but can not locate the source itself. This dissociation of abilitias implies that the profound sound localization deficits resulting from auditory cortex damage discovered in past are not the consequence of a sensory or perceptual loss, but instead are probably the consequence of an auditomotor or associative loss. [Supported by grants NDS-7726, NDS-7468, MH-11218 to Florida State University, and grant HD 02528 to the Bureau of Child Research, University of Kansas.]
Variability in the day-to-day noise environment near airports
Authors: Bishop Dwight E.
Published: October 2005

The 24-h noise data now being acquired at a number of airports are providing information on the day-to-day variations in noise environment. Community noise equivalent level (CNEL) data acquired at four airports (three civil and one military), based on measurements at 16 positions and for periods ranging from 13 to 193 days, show trends that may be useful for planning purposes. Plots of the standard deviation for the daily values (weekdays only for the military airport) versus the logarithm of a typical distance from the aircraft to the monitoring position show that the variability increases slowly with distance from the aircraft. The standard deviations at positions under the landing path (distances of approximately 400 ft) are of the order of 2 dB. The standard deviations increase to the order of 3 dB at a distance of 3000 feet. The weekday and weekend noise environment near the military airport shows distinct differences reflecting the large reduction of operations on weekends. Correlation of daily noise data (weekday and weekend) with the gross number of operations for the military airport confirm the expected increase in CNEL values with the logarithm of the number of operations.
Predicting ambient sound levels
Authors: Kessler F. M. , Gottlieb P.
Published: October 2005

Predicting community noise levels requires the addition of background ambient sound levels and the source's contribution to ambient sound levels. Baseline data are obtained, from community sound surveys, in the form of histograms and cumulative distributions. Source (for example, a construction site) sound level data are also obtained as histograms and cumulative distributions. The problem of combining the two distributions is made somewhat difficult by the logarithmic nature of the physical variable. The prediction is accomplished by the mathematical convolution of the variables representing baseline and the source. Since the data are provided as histograms rather than continuous probability density functions, it is convenient to decompose the density functions into a sequence of dirac delta functions. The result, h(z) = Σαβδ{z − 10log[antilog(i/10) + antilog(j/10)]}, can be programmed for a rapid and efficient computation. Results are provided for the combination of various construction site sound level distributions (e.g., single valued, normal, biomodal) with community background ambient sound. Data are shown of the effect on community noise of a source contribution which is attenuated by distance.
Community noise study of a pet hospital
Authors: Salter C. M. , Rodkin R. B.
Published: October 2005

The proposed conversion of an existing commercial building into a veterinary hospital was met by stiff opposition from the adjacent homeowners. They feared that offensive noises and odors would emanate from the building. In this paper, the roles of the hospital owners, their lawyers, and acoustical consultants; the residents, their lawyers, and their acoustical consultants; and the planning commission and their representatives are discussed. Criteria used to evaluate the severity of the potential nuisance, measured ambient noise levels, and predicted interior noise levels are presented. The architectural modifications incorporated into the building to control noise are evaluated. Costs incurred by the owners and the residents are discussed.
Effects of contralateral stimulation on threshold adaptation
Authors: Hopkinson N. T.
Published: October 2005

The effects of sustained contralateral broadband stimulation on threshold adaptation were studied in normal and pathological ears. Three levels of noise were presented contrallaterally while each of three pure tones was used as the test signal. Signals were continuous for a maximum of sixty seconds, to compare adaptation in pathologicals with that in normal ears. Masked thresholds and threshold adaptation differentiated between pathological ears and normals. In the pathological group, those with sensory dysfunction showed different effects from those with neural pathology. The “sorting” stimulus is the continuous broadband high-level noise which elicits the stapedial reflex. An indirect measure of adaptation of the reflex occurs at different rates than normal among the ears selected for pathology and contrary to direct measures, may avoid areas of overlap between sensory and neural pathologies. The relevance of the reflex are to normal and abnormal function will be discussed as it relates to experiments that involve high level or bilateral stimuli. [Work supported by NINCDS.]
Ultrasonic shear relaxation of polystyrene-cyclohexane mixtures in the critical region
Authors: Miyake Yasuhiro , Izumi Yoshinobu , Kono Ryusuke , Yoshizaki Haruyo
Published: October 2005

Although there have been many studies on longitudinal relaxation in liquid mixtures near the critical point, there has been no previous report on shear relaxation in polymer solutions. A coupling between the longitudinal and shear deformations apparently causes a critical slowing down in shear. The measurement is conducted on the critical concentration at the fundamental frequency of 51.2 KHz and the third harmonics, using the crystal torsional method. The velocity and absorption at the normal state generally agree with the Rouse theory. The cusp in absorption is remarkable in the vicinity of the critical temperature Tc=27.105°C. Below Tc the Landau-Khalatonikov mechanism contributes significantly to the excess absorption, coupled with a resonance. The behavior is attributable to the typical second-order transition phenomena based on the hindered rotation of back-bone chains.
Magnetostrictive properties of terbium-holmium-iron compounds
Authors: Timme R. W. , Koon N. C.
Published: October 2005

For application in sonic transduction, a large strain of the active element is desirable; however, the advantage of the huge room-temperature magnetostriction (≃0.2%) of certain rare earth-iron alloys such as TbFe2 is tempered by its large anisotropy energy. Ternary alloys can be produced with the addition of holmium or dysprosium and the result is a compound with a respectable magnetostriction and a much lower anisotropy. This is a report of the magnetostriction properties of the terbium-holmium-iron system in the vicinity of minimum anisotropy. Room-temperature data on the static and reversible magnetic permeability, static and dynamic magnetostrains, magnetostrictive constant d33, elastic constant s33B, and magnetomechanical coupling constant k33 are presented as a function of magnetic field and alloying composition. A comparison of these properties to those of nickel is made and the implications to engineering application are discussed.
Properties of metastable liquids using acoustic levitation
Authors: Apfel R. E.
Published: October 2005

A recently described technique for measuring a known function of adiabatic compressibility and density (coined the “compressadensity”) of very small droplet samples of liquids [J. Acoust. Soc. Am. 57, S56 (1975)] has been applied to the measurement of the properties of greatly superheated liquids. This technique involves comparing the conditions required for the acoustic levitation of a small droplet of the test liquid in a nearly immiscible host liquid with the conditions required for the levitation of a reference liquid of known properties. This information and the results of the theory of Yosioka and Kawasima for the “Acoustic Radiation Pressure on a Compressible Sphere” [Acustica 5, 167 (1955)] allow one to predict the “compressadensity” of the test liquid. Results for some superheated liquids will be presented and the limits on the accuracy of the levitation technique will be discussed. [Work supported by the U.S. Office of Naval Research.]
Liquid monopropellant ignition by acoustic cavitation
Authors: Campagna M. S. , Crum L. A.
Published: October 2005

It is known that acoustic cavitation can provide an effective means of concentrating mechanical energy; the pressure inside a collapsing cavity may reach thousands of bars and the temperature thousands of degrees. Liquid propellants have been considered for use in large military guns for several years but lack of internal ballistics control has prevented their implementation. An acoustic technique, utilizing cavitation, is being examined for possible use in one specific problem area, propellant ignition. It has been determined that an acoustic horn, developing an intensity of approximately 20 W at its tip, can initiate in the propellant free oxygen release, metal oxidation, and, in certain instances, ignition. It is suggested that this technique has possible use as an ignitor in a liquid propellant gun or as a sensitivity-test mechanism for various propellant lots. [Work supported by the Naval Ordnance Station, Indian Head, Maryland.]
Auditory threshold shift in nonhuman primates chronically exposed to low-level noise
Authors: Schenib B. T. , Stebbins W. C. , Moody D. B. , Johnsson L.-G. , Muraski A. A.
Published: October 2005

Four Old World monkeys were exposed 24 h a day for 90 days to a 90 dB SPL octave band of noise centered at 2 kHz. Monaural pure-tone thresholds were determined prior to, during, and after exposure by means of the tracking method, using operant conditioning with positive reinforcement. Maximum TTS was observed at 2.8 kHz. For three animals, the TTS function showed an initial plateau of 19 to 21 dB after 7 to 12 h of exposure; the TTS function in the fourth animal reached an initial plateau of approximately 60 dB by the fourth day of exposure. Further shifts from this plateau were observed in the TTS functions for three of the animals. Following the period of exposure, threshold in two of the animals recovered to within 5 dB of baseline after 72 h. The remaining two animals showed PTSs of 15 and 25 dB. Microscopic examination of the organ of Corti indicated some scattered hair cell loss in the ears of all animals. Details of the histopathology and hair cell counts are presented. Implications of these results to noise-induced threshold shift in humans and chinchillas are discussed. [Work supported by grants from NINDS and NIOSH.]