bluuebunny/crossref_metadata_2025 huggingface dataset:
Attenuation characteristics of hearing aid earmolds
Authors: Englehart J. M. , Frank T.
Published: October 2005

When a hearing aid is worn but not turned on, the earmold used in conjuction with the hearing aid, may act as a personal ear protective device against traumatizing noise. The purpose of this research was to evaluate the amount of attenuation provided by several commonly used earmolds and an E-A-R® plug experimental earmold. The amount of attenuation was determined for ten experienced normal hearing listeners employing the ANSI S3.19, 1974 method. The listener's nontest was occluded by an E-A-R plug and covered by an earmuff to eliminate it from participation. The test ear, in the occluded conditions, contained the earmold under test connected via tubing to an ear level hearing aid (turned off). The attenuation provided by the commonly used earmolds was similar averaging approximately 10–15 dB from 125 to 1000 Hz and 22–35 dB from 2000 to 8000 Hz. The attenuation provided by the E-A-R plug earmold was significantly greater averaging approximately 25–30 dB from 125 to 1000 Hz and 40–45 dB from 2000 to 8000 Hz. The implications of these findings in reference to the OSHA allowable noise levels will be discussed. [E-A-R used with permission of E-A-R Corporation, Indianapolis, IN.]
Tone generation due to laminar air flow over a cavity mounted in a flat plate
Authors: Elder S. A. , De Metz F. C.
Published: October 2005

Two distinct regimes of tone generation have been isolated for a cavity mounted in a laminar boundary layer in air. The first is a cavity resonance phenomenon similar to that excited by turbulent flow (F. C. De Metz and T. M. Farabee, Paper No. 77-1293, AIAA 4th Aeroacoustics Conference, 1977; S. A. Elder, J. Acoust. Soc. Am. 64, 877 (1978)]. The second is a species of edgetone oscillation which occurs when sufficient damping material is inserted into the cavity to prevent normal mode excitation. By extension of the methods used in earlier studies of turbulent air flow tones, it is possible to model the feedback coupling mechanism for each regime. For the edgetone case, Strouhal number is found to occur close to the value corresponding to maximum instability of the separated shear layer. In the case of resonant cavity oscillation. Strouhal number is somewhat dependent on aspect ratio of the cavity mouth opening. For narrow slot profiles, the resonant oscillation condition is dominated by ξ1 interface waves, resulting in a simple Strouhal number formula. [Work partially supported by a GHR contract with the Naval Ship Systems Command, administered by the David W. Taylor Naval Ship Research and Development Center, Carderock, Maryland.]
Summating potential (SP) tuning curves
Authors: Cheatham Mary Ann , Dallos Peter
Published: October 2005

Tone-on-tone masking and differential electrode techniques have been employed to investigate the tuning properties of the DIF summating potential (SP). In these experiments the SP is elicited by tone bursts of set frequency and intensity while a second tone of variable frequency and level is used to reduce SP magnitude to a desired degree. The SP tuning curve is generated by frequency—intensity pairs formed by the masker that yield a preset decrease. Results reveal that DIF and whole nerve action potential (WNAP) tuning curves are quite similar while tuning properties of the DIF+ are more analagous to CM interference functions. The dependence of various features of these SP tuning curves upon stimulus frequency and level are detailed in the present work. [Work supported by NINCDS.]
The costs of noise
Authors: Lent Linda K. , Peppin Richard J. , Rodman Charles W. , Mirabelli Richard E.
Published: October 2005

The justification for, or arguments against, noise control is often based on the economic costs of abatement, the dollar costs of incurred illnesses or compensation to workers, or the dollar degradation of property caused by industrial or community noise. But there are other costs that are difficult to quantify in any terms, much less in dollar amounts. This paper provides a brief discussion of the problems of trying to quantify concepts that essentially cannot be quantified.
Prediction of noise attenuation from shielding effects of plant structures
Authors: Wang John S.
Published: October 2005

A technique has been developed for estimating the noise attenuation resulting from the shielding effects of plant structures and equipment between the noise source and the community. The study was aimed at improving the prediction accuracy in community noise estimates. The shielding noise attenuation has been determined with an acoustical modeling technique which involved using physical scale models with a 32 to 1 ratio in a simulation of the full-scale noise propagation. The technique has been successfully validated by comparing the full-scale field data to the model data. The recommended charts for estimating the shielding attenuation of noise have been developed based on the generalized results obtained from various combinations of plant models. The parameters that are needed to determine the shielding noise attenuation include equipment density, shielding unit dimension, and noise source height. Their effects on the shielding noise attenuation have been assessed on a frequency basis. Typical noise attenuation is approximately 6 dBA for a shielding unit with a dimension of 100 (328 ft).
Vibration damper for power saws
Authors: Allen Clayton H.
Published: October 2005

A noncontacting means for reducing vibration in, and noise radiation from a saw blade was first described at the San Diego Meeting of the Acoustical Society in November 1976. Some 15-dBAnoise reduction was demonstrated for a 10-inch radial-arm saw ripping a 1-in. thick maple board. The damper resembled a disk brake by its use of a caliper action to force damping elements toward opposite sides of the blade, but these elements are held out of contact by a thin film of pressurized air acting as a static air bearing, thus a negligible drag force acts on the moving saw blade. Improvements have been made and the application expanded to include metal and plastic cutting. The latest model is wholly contained within the saw guard so that it is substantially unnoticeable to the operator except that the operation is quieter. Arrangements are being considered for licensing agreements to manufacture and distribute commercial versions of this noise control device for various industrial sawing operations. Potentials and limitations for application of this damper to larger saw configurations will be discussed.
Prediction of velocity-gradients in seafloor sediments
Authors: Ogushwitz P. R. , Stoll R. D.
Published: October 2005

An acoustic model for unconsolidated sediments [R. D. Stoll and G. M. Bryan, J. Acoust. Soc. Am. 47, 1440–1447 (1970)] was used to predict velocity gradients of dilatational and shear waves in two representative seafloor materials (quartz sand and calcareous clay). Sediment porosity and permeability were treated as functions of depth. Porosity profiles were based on Deep Sea Drilling Project data. Permeability was calculated from porosity using empirical formulae. The complex bulk and shear rapdull of the skeletal frame were treated as functions of overburden pressure, using empirical relations obtained from experiments in soil mechanics. Predicted velocity gradients for compressional waves in clays and sands range from 0.3–2.2 s−1; these results agree closely with values published in the geophysical literature. Predicted gradients for shear waves in clays range from 2.4 s−1 near the sediment-water interface to 1.0 s−1 at a depth of 500 m; these results fall within a range of shear-wave gradients predicted from in-situ measurements of saturated terrestrial materials [E. L. Hamilton, Geophysics 41, 985–996 (1976)].
Propagation of the fourth order coherence function in an anisotropic random medium
Authors: Beran Mark J. , Toor Moshe
Published: October 2005

The low frequency propagation of the fourth order coherence function through an anisotropic medium is investigated by employing the parabolic approximation and perturbation techniques. Theoretical expressions are derived for the intensity fluctuations and correlations of an initial plane wave signal that has propagated a distance z into the medium. The expressions are valid for anisotropic media in which klH ≫ and klv2/IH ≪ 1, where k is the radiation parallel and perpendicular to the propagation direction z. Numerically, we also calculate the intensity fluctuations of a plane wave, whose propagation direction forms an arbitrary angle with the principle axes defined by IH, and lv. We find that the magnitudes of the fluctuations are very sensitive to the propagation angle. Two examples are discussed: an exponential correlation function which approximates the ocean temperature microstructure, and a Gaussian correlation function. [Work supported by NSF Contract ENG76-11812.]
A quantitative definition of depth excess—How much is enough?
Authors: Walkinshaw H. M.
Published: October 2005

The amount of depth excess available below the sound channel is a vintage working concept used to acoustically characterize an area: yet the minimal amount considered “sufficient” has eluded precise definition for many years. An ongoing study of convergence zones has exposed certain general properties of their structure and dimension which suggest a simple but exact definition for depth excess which meets a sufficiency criterion. In any ocean with a deep sound channel where water depth permits the full development of convergence zones, such zones are bounded at a maximum in range by the θ = 0° surface-grazing RSR ray and at a minimum in range by an RSR path for which dR/dθ = O. The presence of this path, which has been named the “simple” caustic ray, indicates the formation of strong caustics which migrate only slightly with depth and range. Depth excess is defined as the difference between the vertex depth of the surface-grazing RSR ray (the bottom of the sound channel) and the vertex depth of the “simple” caustic ray. Conditions for the existence of this unique path are given. Transmission measurements and models are used to demonstrate the efficacy of the new depth excess definition.
Low frequency underwater sound propagation measurements west of the NOSC oceanographic tower
Authors: Northrop J. , Stixrud T. E.
Published: October 2005

Acoustic signals from 50 SUS charges detonated at ranges from 1 to 50 mi west of the NOSC tower were recorded in December, 1978 on both hydrophones and three-component geophones buried about 1 ft in the sediment and cable connected to the tower. An additional hydrophone was placed on the bottom. Both ground and water arrivals were observed for shots within the 400 fa curve (at ranges up to 10 miles) with only water arrivals noted for shots in deeper water of the San Diego trough. Propagation paths in the water were SR/BR (Surface Reflected/Bottom Reflected) throughout, with pronounced up-slope propagation near the receivers. Spectrum analysis of the various arrivals shows that the S/N ratios of the ground and water arrivals are similar below 20 Hz for shots within the 400 fa curve. The ground arrivals, however, have a longer duration (several seconds) than the water arrival (<1 s) because recordings were obtained of both compressional and shear waves refracted in the sediment and rock layers below the sea floor. [Work supported by ONR.]
Acoustic propagation in shallow water over a low velocity bottom
Authors: Rubano L. A.
Published: October 2005

Acoustic measurements were performed off the coast of Corpus Christi, Texas in 30 m of water. Explosive charges, weighing 14 oz each, were detonated at specified depths to selectively excite and temporally separate the first and second acoustic normal modes. An array of eight hydrophones with an element spacing of 3.7 m was vertically deployed to measure the spatial amplitude distribution of the modes in the water column. Vertical amplitude distributions of the first and second modes, transmission loss in one-third octave bands, and dispersion analyses are presented and compared with computations from a three-layer normal-mode program. Estimates of sound speed in the bottom were obtained from seismic refraction analysis and cores taken from the water-sediment interface. A low velocity layer was responsible for the high attenuation of frequencies above 350 Hz and for the shape of the water-wave portion of the group velocity dispersion curve.
Mode attenuation measurements in shallow water off the coast of Panama City, Florida
Authors: Caswell W. R.
Published: October 2005

A technique that uses both the spatial and temporal properties of sound propagation in shallow water is applied to resolve and measure the attenuation of individual acoustic normal modes. This method has permitted the first three normal modes to be isolated over a broad frequency range for short range experimental data obtained using small explosive charges as a source. The measured mode attenuation is used to deduce the frequency dependence of acoustic attenuation in surficial sediments. The results obtained are compared with previous measurements at this site. [This research was performed under contract to The Applied Research Laboratory of The Pennsylvania State University. This research was sponsored by the Naval Sea Systems Command.]
Generation of ultrasonic leaky waves at liquid-solid interfaces
Authors: Adler Laszlo
Published: October 2005

Recent experimental investigations by M. A. Breazeale, L. Adler, and G. W. Scott [J. Appl. Phys. 48, 530–537 1977)] have verified the theory of Bertoni and Tamir [Appl. Phys. 2, 157–172 (1973)]. Excitation of leaky Rayleigh waves takes place at the liquid-solid interface when a Gaussian ultrasonic beam is incident at or near the Rayleigh angle to the interface. Now we should like to report two additional examples of leaky wave generation: (1) When a thin (less than a wavelength) ceramic layer is added to a metal surface, leaky waves are generated. The velocity and amplitude distribution of these waves will be discussed. (2) For interfaces such as water-Plexiglas no real solution of the leaky Rayleigh velocity exists since the sound velocity in the water is larger than the shear velocity in Plexiglas. By studying the reflection of an incident Gaussian beam from water-Plexiglas interfaces we have observed leaky waves near the longitudinal critical angle. Similar observations were made at water-sediment interfaces. [M. A. Breazeale and L. Bjørnø, Proc. Ultrasonics Int., 1977, pp. 440–444]. [Research supported in part by the Office of Naval Research.]
Minimum reflectance of inhomogeneous layers; normally incident, monochromatic sound waves
Authors: Scharnhorst K. P.
Published: October 2005

We discuss the problem of determining the minimum reflectance achievable with a given inhomogeneous layer thickness, substrate input impedance and range of allowed material parameters for normally incident, monochromatic sound waves. The density and dilitation modulus are permitted to vary independently. Real and complex moduli are considered. In the case of real parameters, analytic solutions for the switching curves and sublayer thicknesses of the multilayer system are presented. The resulting sublayer sequences will be discussed. The sequences are periodic and we show that for certain combinations of parameters the reduced unit cell thickness is approximately equal to 2π radians. General results concerning the parametrization of sublayers in the case of complex moduli will be discussed. Examples of particular solutions will be presented.
Automatic alignment of a phonetic transcription with articulatory events from x-ray data of continuous speech utterances
Authors: Nelson W. L.
Published: October 2005

To facilitate the access to, and analysis of, the large body of speech articulation data being accumulated with an x-ray microbeam system [Fujimura, Miller, and Kiritani, J. Acoust. Soc. Am. 60, S64 (1976)], pattern-matching procedures have been developed to link these data bases with phonetic transcriptions of the speech material. A method previously used for isolated-word data [Nelson, Miller, and Macchi, J. Acoust. Soc. Am. 63, S32 (1978)] is now extended to process the continuous speech data. The sequence of stressed vowels and nonvoiced consonants in the phonetic transcription are matched with occurrences of mandible-height minima and nonvoiced segments in the articulatory and acoustic data. The minimum-cost solution for matching these two types of events is found by a dynamic programming procedure, using a cost function based on the overall error in predicting the duration of these events and the intervals between them, plus a cost for the nonoccurrence of predicted articulation events in these intervals.
Inferences of airway geometry from acoustic reflections measured at the mouth
Authors: Fredberg J. J. , Wohl M. E. B. , Dorkin H. L. , Glass G. M.
Published: October 2005

To test the hypothesis that upper and central airway geometry can be inferred from acoustic reflection data recorded at the mouth, we have computed the inferred values and compared them with estimates of tracheal cross-sectional area obtained from chest radiographs in five subjects. Reflection data were transformed into an inference of cross-sectional area as a function of distance from the lips [Sidell and Fredberg, J. Biomech. Eng. 100, 131 (1978)]. With the subjects breathing air, the inferred tracheal areas were markedly overestimated. With the subjects breathing 80% helium and 20% oxygen, there was good intrasubject agreement between acoustic and radiologic estimates of tracheal dimensions, in spite of marked inter-subject variability. These studies confirm that features of airway geometry between the lips and carina can be determined quickly and noninvasively in individual subjects. [Supported by NHLB1 contract ♯N01-6-2901 and a P.B. Frances Fellowship (HLD).]
Mechanisms for the control of vocal frequency
Authors: Hollien H. , Hicks J. W.
Published: October 2005

It is well known that control of vocal frequency is determined primarily by variation in the mass and stiffness of the vocal folds and by subglottic pressure. In turn, variation in vocal fold mass and stiffness results (in part, at least) from changes in vocal fold length. But how is vocal fold lengthening accomplished physiologically? There is no question but that the major control for this action results from contraction of the cricothyroid muscle—which reduces the CT space and, hence, stretches the vocal folds. However, we are challenging the notion that cricothyroid m. action is the only (major) factor in that regard. In order to do so, the following steps were taken. (1) Mean and maximum variations in vocal fold length were calculated. (2) Estimates were obtained of laryngeal cartilage size. (3) A variety of potential laryngeal cartilage dimensions were calculated. (4) Based on these values, appropriate computer software was developed. (5) By this means, the effect of the CT mechanism on vocal fold length was tested. It was found that CT activity alone could not account for all of the lengthening observed. A complimentary mechanism then was sought. From examination of lateral radiographs, we observed that the shadows of the arytenoid cartilages appear to move posteriorly as a function of increases in f0. This apparent movement was measured on the x rays of a number of subjects. The values obtained appear to account for the balance of vocal fold elongation. The results of some EMG studies support this explanation; others do not. The relationships in question will be discussed.
Articulatory properties of /s/ in selected consonant clusters
Authors: Hasegawa Akira , Christensen John M. , McCutcheon Martin J. , Fletcher Samuel G.
Published: October 2005

The objective of the study was to delineate articulatory characteristics of /s/ production in selected consonant clusters. The /s/ consonant was embedded in meaningful /s/C1/æ/C2 words (C1 = /p, m, t, n, 1/, C2 = /t, k/) in a sentence. They were presented randomly. Information on linguapalatal contact, lip and mandible positions, and speech spectra was obtained simultaneously every 10 ms from three normal adult speakers of English. Analysis of these data revealed (1) unique medial /s/ grooves were formed in most instances, (2) for all the clusters, the minimum /s/ groove was first established near the onset of stable /s/ frication noise, (3) the groove width in the consonant was similar to that for the prestressed, prevocalic /s/ despite substantially reduced /s/ frication duration for the consonant cluster, (4) tongue occlusions for the alveolar consonants /t, n, l/ appeared anterior to the minimum /s/ groove. The results indicate precise medial groove formation during /s/ production with some interesting kinematic properties. [Work supported by NIH grant NS-11852-04.]
The effects of antagonistic gestures on temporal and amplitude parameters of anticipatory labial coarticulation
Authors: Sussman H. M. , Westbury J. R.
Published: October 2005

An attribute of the speech production system is the ability to anticipate articulatory targets. This study investigated how the presence and proximity of prior antagonistic versus neutral phonetic gestures affected anticipatory coarticulation for lip rounding. EMG activity was recorded from orbicularis oris superior (OOS)—the agonist for lip rounding; and risoris (RIS) the antagonist, for three subjects repeating the tokens /kikstu/, /kakstu/, /tiku/, and tuki/. Comparing a three-member cluster to a single consonant enabled us to test the notion of time-locked anticipatory coarticulation. Temporal onset values of OOS with respect to /u/ onset and in relation to cluster duration revealed earlier relative OOS onset for the neutral /kakstu/ environment versus the antagonistic lip spread environment in /kikstu/. All subjects revealed greater OOS amplitude as measured by averaged integrated EMG for /kikstu/ versus/kakstu/. Anticipatory coarticulation was found to be nontime locked and a function of number of intervening segments. Lip movement was measured and onset of lip protrusion preceded OOS onset illustrating the operation of elastic recoil of the lip in moving from a prior spread position to a protrusion.
Manifestations of rhythm and stress in physiological measurements of jaw activity in speech
Authors: Stone M.
Published: October 2005

This study examined the effects of stress level on jaw movement. Jaw displacement was measured by a strain gauge transducer during the production of normal, whispered and fast repetitions of five nonsense syllable phrases. Jaw velocity was extracted by an analog differentiator. Jaw velocity was compared to the perceived levels of stress of the nonsense syllables at the two rates of speech and while whispering. Jaw velocity was found to be significantly related to stress level. Three levels of stress—unstressed, stressed, and prominently stressed or beat syllables—were distinguished on the basis of differences in opening vowel velocity. [Work supported by NIH Grant DE-03631.]
Mandible position and stress
Authors: Condax I. D.
Published: October 2005

In English, a stress-timed language, each stressed vowel is associated with a downward excursion of the jaw, whereas unstressed vowels are not [O. Fujimura, ASA paper (June, 1977)]. Fijian has been assumed to be syllable-timed [C. Hockett, Manual of Phonology, 59 (19551] and described as stress-timed [A. J. Schutz, Hawaii Working Papers in Linguistics, 8.2.86 (1976)]. Meaningful Fijian sentences where segmental influences on vowel duration were minimized were studied. All low vowels showed a downward excursion of the jaw, large for stressed [a] in lexical words, moderate or small for unstressed [a] in lexical words, and small for unstressed [a] in particles. The durations between the onsets of the vowels measured acoustically were proportional to the magnitude of the downward excursion of the jaw. Thus the necessity for making a separate jaw movement for nearly every syllable may contribute to keeping the syllable durations more uniform than in English, but substantially less than identical for similar syllables with different stress. This finding may account for the differences in descriptions of Fijian regarding its status as stress- or syllable-timed.
Cues for interpreting early child speech
Authors: Landahl K. L.
Published: October 2005

A word spoken in isolation often shows more precision in its production than that same word spoken in a longer utterance. Articulatory imprecision in speech probably occurs because speech interpretation involves contextual cues This situation suggests the following questions with regard to child speech: (1) Are the child's words phonetically stable whether produced in isolation or in a longer utterance? (2) To what extent do adults use context versus acoustic cues in listening to child speech? Data were derived by presenting a taped conversation with adults and an 86-week-old child to six subjects: the child's parents, two linguists, and two non-linguists. These subjects each heard four different versions of this material: the child's words only, excised by use of a computer editing system; the child's utterances only; the entire tape; and the entire tape with written notes of the non-linguistic context. Subjects were asked to identify forms which they considered to correspond to words in the adult language.
A physioacoustic model of the infant cry and its use for medical diagnosis and prognosis
Authors: Golub Howard L.
Published: October 2005

A total of 98 infant pain cries were recorded during the three-day blood test (P.K.U. heel stick) in order to test some of the important aspects of a cry production model. The infants ranged in age from 2–4 days; 20 were judged to be medically abnormal, 23 were questionable, and 55 were normal. The model was developed by utilizing the adult acoustic theory of speech production modified by physiological and anatomical hypotheses for neonates. The most important hypothesis concerns the control strategies of muscles involved in cry production. It is postulated that neonates control their muscles, especially the smaller muscles of the larynx, in a quantal fashion. Based on this model, a number of acoustic parameters were selected, and were extracted from the recorded cries using digital techniques. The parameters included formants and F0 vs time, timing and intensity information, determination of laryngeal mode, and nasalization. Relevant statistical analysis was performed to determine class ranges for each parameter of the model and to compare data from different medical classes. It is hoped that this model and the corresponding computer analysis will help to facilitate the use of the infant cry for medical purposes. [Work supported by NIH.]
Oral sensory and temporal articulatory changes as a result of lateral auditory interruptions during speech
Authors: Crary M. A. , Fucci D. , Petrosino L. , Bond Z. S.
Published: October 2005

Lingual vibrotactile thresholds were obtained for 10 normal subjects under four different conditions: (1) bilateral auditory masking during reading, (2) right ear auditory masking during reading, (3) left ear auditory masking during reading, (4) no auditory masking during reading. Baseline thresholds were obtained prior to any exposure to masking. To investigate changes in the articulatory patterns of the subjects under masking conditions, four acoustic measurements were obtained from a test word embedded in a stimulus sentence: (1) stop closure duration, (2) voice onset time, (3) vowel duration, (4) duration of final stop closure. The different types of auditory disruptions during speech production resulted in a decrease in lingual sensitivity as well as temporal reorganization of articulatory speech patterns. Although fluctuations were observed in speech segment measurements during masking conditions, laterality of masking appears to have no effect on temporal articulatory speech patterns.
Long-term compensation for upper-lip immobility
Authors: Hanson R. J. , D'Antonio L. L.
Published: October 2005

Previous studies of short-term articulatory dynamics have demonstrated that the lips, jaw and tongue act together in a coordinated, synergistic manner and that restraints on one articulator require compensation by others to preserve acoustic contrasts [B. Lindblom and J. Sundberg, J. Acoust. Soc. Am. 50, 1166–1179 (1971); C. Riordan, J. Acoust. Soc. Am. 62, 998–1002 (1977)]. It has also been shown that the lower lip may move independently of the jaw when required by competing articulatory demands [H. Sussman, P. MacNeilage, and R. Hanson, J. Speech Hear. Res. 16, 397–420 (1973)]. The present study explores the possibility that lip and jaw independence may be used to preserve acoustic contrasts in long-term articulatory compensation for anatomical abnormalities. The lip and jaw movements of two subjects with surgically repaired cleft lip and palate were studied using frame-by-frame, pellet-tracking analysis of a 60 frame/s x-ray film and acoustic analysis of a simultaneous audio recording. Subjects repeated /əCVCə/ utterances (where C = /p, m/ and V = /i, u, a, æ/) and the data were analyzed from the point of maximal closure for the first consonant, through the vowel to the same point in the second consonant. Results indicate that while the subjects did approximate normal acoustic targets: (1) the upper lip remains immobile; (2) the lower-lip moves with greater velocity and to a greater extent than expected; and (3) jaw movement was relatively unaffected. These results can presumably be attributed to the anatomical abnormalities and surgical history of the subjects which rendered the upper-lip an ineffective articulator and caused the lower lip to compensate with faster and larger movements.
Supraglottal air pressure during a valsalva maneuver
Authors: Brown W. S. , McGlone R. E.
Published: October 2005

Supraglottal air pressure (P10) is defined as the build-up of air pressure within the oral cavity as a result of articulatory resistance to pulmonic air flow. Two major assumptions are inherent in this definition; (1) a column of air moves through the vocal tract supplied by a pulmonic source; (2) P10 results directly from a partial/complete resistance to this air column. The present study was a test of these two assumptions. Subjects repeated VCV syllables containing the cognate pairs /p,b/, /t,d/, and /s,z/ during a valsalva maneuver (absence of pulmonic air flow). Peak measures of P10 were obtained from the consonant productions. Results indicated that even in the absence of pulmonic air flow, the oral pressures generated were similar to those recorded for normal speech. Moreover, the voice-voiceless distinction typical of normal speech was observed for the valsalva productions. These results indicate that we may need to re-evaluate present descriptions of P10, especially in terms of the role of the pulmonic air source. Also, it may be that P10 is not merely a result of laryngeal/articulatory resistance, but is phoneme specific.
Cochlear models: Two-tone suppression and the second filter
Authors: Hall J. L.
Published: October 2005

With advances in our understanding of the auditory periphery, models of cochlear mechanics have evolved from descriptions of existing data to the point that they can suggest meaningful observations that should be made and predict expected outcomes. As an example, we discuss relationships among mechanical nonlinearities in the inner ear, two-tone suppression, and the auditory “second filter.” Electrophysiological two-tone suppression data indicate that excitatory tuning curves (stimulus intensity required to elicit a specified amount of activity in a primary fiber, as a function of frequency) are more sharply tuned than suppressive tuning curves (stimulus intensity required to suppress the response to a continuous tone at the fiber's characteristic frequency by a specified amount, as a function of frequency). Model simulations which attempt to account for the above difference suggest that there must be a stage of sharpening between the physical variable governing two-tone suppression (tentatively identified as velocity of the basilar membrane) and the physical variable governing neural excitation. An experiment that would unequivocally demonstrate the simultaneous existence of two representations of the stimulus with significantly different tuning properties in the cochlea is described. The future evolution of cochlear modelling, incorporating nonlinear two-dimensional models, is discussed.
Finite element analysis of a barrel-stave underwater sound projector
Authors: Armstrong B. A. , McMahon G. W.
Published: October 2005

The barrel-stave projector comprises several concave metal staves joining two cylindrical head pieces which are driven axially by a stack of piezoelectric ceramic. This radiating system has been analyzed using an axially symmetric finite element model. The metal staves are modelled as an anisotropic material having normal axial and radial stiffness but low hoop stiffness. The performance of an experimental unit, 12 cm long and 7.6 cm in diameter, which resonates near 1500 Hz, is compared with predictions of the finite element model. Additional computer modelling has been carried out with an anisotropic carbon fiber composite replacing the metal staves.
Response of a linear-network ear model to impulsive stimuli
Authors: Kalb Joel T.
Published: October 2005

An argument has been made that the upper limit of stapes displacement during impulsive stimulation can possibly influence hearing loss [G. R. Price, J. Acoust. Soc. Am. 56, 195–197 (1974)]. Calculations of stapes motion were made based on a linear-network model of the middle and external ear and Fourier analysis of idealized and actual transient waveforms typical of industrial and military sources. The acoustical attenuation of a circumaural ear protector was included in the analysis by an idealized, single cavity, lumped-element acoustic impedance network.
Human response to impulse noise
Authors: Schomer Paul D.
Published: October 2005

This paper reviews almost 50 studies dealing with human response to impulse noise and includes virtually every paper in the open literature dealing with either annoyance or community response. Most of the papers come from the mid 1960's through the mid 1970's and deal with sonic boom sonic boom noise. However, several recent papers deal with impulse resulting from military blasts (artillery, armor, bombs, etc.) and open pit mining blasts. Based upon these sources, this paper attempts to answer such questions as “What type of noise measure is best for predicting the human response to noise?” and “When people respond indoors to a blast or boom stimulus do they respond to the noise, the noise induced vibration or both?”. Finally an indication is also given as to results of the recent community attitudinal survey administered by the Construction Engineering Research Laboratory which deals specifically with the impulse noise from artillery and the noise from helicopters.
The duration of stop consonants
Authors: Stathopoulos E. T. , Weismer G.
Published: October 2005

It is well known that the duration of a stop consonant in the intervocalic, poststressed position may serve as a cue to that stop's voicing characteristic [L. Lisker, Lang. 33, 42–49 (1957)]. More recent research has suggested that when stop-closure durations are examined in a variety of positions, the voiceless stops have greater duration than the voiced stops only in the intervocalic, poststressed position [L. Lisker in A. Valdman [Ed.], Papers in Linguistics and Phonetics to the Memory of Pierre Delattre, 339–343 (1972)]. The present research was designed to provide additional data on stop-closure durations as a function of (1) voicing, (2) stress, (3) vowel context, and (4) place of articulation. Six subjects produced a series of nonsense disyllables of the form CVCVC in a carrier phrase; for each disyllable, one consonant was a “test consonant” and the other two were controls. The test consonant was systematically varied with respect to voicing, stress and position-in-disyllable. Vowels in the disyllable were also varied systematically within the stressed syllable, and included /i/, /l/, u/, and /æ/. Preliminary analyses show that for some subjects, the dorsal stops are affected by stress and position differently than are the apicals and bilabials.
Vowel durations in the conversational speech of children
Authors: Weismer G. , Ellis S. M. , Chicouris C.
Published: October 2005

Previous data on segment durations produced by children have been based on imitated speech samples or repeated nonsense syllables [e.g., F. G. DiSimoni, J. Acoust. Soc. Am. 55, 362–363 (1974); B. L. Smith, J. Phon. 6, 37–68 (1978)]. One result of this research seems to be that children in the three-to-six-year old range have vowel durations which are substantially longer than corresponding vowel durations in adult speech. We considered the possibility that the vowel durations observed in previous studies of child speech are conditioned in part by task variables. For example, if children imitate a live-voice model [Smith, op. cit.], that model may contain vowel durations which are appropriate to adult-child speech and therefore longer than the kinds of vowel durations reported in the literature for adults. The present study reports vowel durations from the spontaneous speech of one three-year old female and one five-year old male. Results include observations concerning vowel duration variability and context effects.
Perception of frequency modulation at low modulation frequencies-the effects of phase angle in a complex modulation
Authors: Klein M. A. , Hartmann W. M.
Published: October 2005

Experiment I estimated the point of subjective equality (PSE) for the perceived width of a complex waveform FM compared to a standard 4-Hz sine waveform FM with excursions, Δfs = ±2.5, ±5, and ±10 Hz. The complex FM was the sum of a 4-Hz fundamental and its third harmonic with 13 the fundamental amplitude. The phase φ between the two components varied from 0 to 7π/4 in steps of π/4. A 2IFC up-down staircase procedure was used. Experiment II was a 2IFC identification task in which subjects distinguished sine FM from complex FM at PSE, with Δfs and φ from experiment I. Results of experiments I and II show similar dependences on Δfs and φ. The complex wave excursion at PSE relative to the sine excursion (I) and the identification error rate (II) both decrease with increasing Δfs and with increasing |φ − π|. The dependences on Δfs support an independent channels model for FM perception, but the dependences on φ argue against this model and favor a model based upon the perception of FM waveform features. [Work supported by the NSF.]
Pitch shifts induced by trailing tones
Authors: Robinette L. N.
Published: October 2005

The pitch of short tone pulses is determined primarily by the frequency of the pulses when they are presented in isolation. Short tone pulses presented with leading tones, however, have been reported to change in pitch [W. M. Hartmann and B. J. Blumenstock, J. Acoust. Soc. Am. 60, S40 (1976) and A. Rakowski and I. J. Hirsh, J. Acoust. Soc. Am. 63, S51(A) (1978)]. In the present study it was determined that a short tone pulse may also change in pitch when presented with a trailing tone. This phenomenon was investigated by having normally hearing subjects match the pitch of short tone pulses which were followed by other tones after silent intervals of from 10 to 1000 ms. Pitch shifts were observed to occur in some cases for pulse-trailer intervals greater than 200 ms. Magnitudes and directions of pitch shifts were also determined as functions of the duration, frequency, and intensity of the trailing tones. Maximal pitch shifts were obtained for shorter pulse durations, smaller values of pulse-trailer interval and longer trailer durations. The results of this experiment suggest that potential influences of pitch shifts must be considered in experiments involving pitch of short tone pulses that are followed by other tones. [Work supported by NIH.]
Temporal versus spectral cues in pitch perception of AM noise
Authors: Houtsma A. J. M. , Wicke R. W.
Published: October 2005

The phenomenon that periodically interrupted white noise exhibits a weak pitch corresponding to the interruption rate has traditionally been regarded as evidence for time-domain pitch processing by the auditory system. Recently, however, it has been pointed out [Pierce, Lipes, and Cheetham, J. Acoust. Soc. Am. 61, 1609–1621 (1977)] that the short-term spectrum of such a stimulus contains several kinds of potential pitch cues. Melodic interval identification experiments were performed with sounds consisting of low-pass filtered noise. modulated by a periodic signal. The modulation signal was either a sine wave, square wave, or pulse train. Melodic intervals were generated by varying the frequency fm of the modulation signal. Modulation frequencies were in the 100–400 Hz range. The low-pass cutoff frequency of the noise, fco, was used as an experiment variable. Identification performance shows a particular dependence on the ratio fco/fm for each type of modulation signal. The form of this dependence is shown to be consistent with both a modified energy detector model (time domain) and a short-term power spectrum correlation model (frequency domain). [Work supported by NIH.]
Infrapitch echo
Authors: Warren Richard M. , Bashford James A. , Wrightson John M.
Published: October 2005

A noise mixed with its repetition after a delay of τ s can produce a pitch corresponding to 1/τ. The accepted range of this classical echo pitch is about 50 through 2000 Hz (τ from 0.02 through 5 × 10−4 s). We have found that echo iterance can be matched with an adjustable click train or synchronous fingertapping down to 2 Hz (although pitch is lost at about 50 Hz). Dichotic echo iterance (initial noise in one ear, echo in the other) can be matched down to at least 1 Hz, but it is not possible to detect which ear leads at infrapitch iterances. Phase shift of monaural or diotic echo by 180° alters apparent iterance at pitch frequencies, but not at infrapitch frequencies. Pitch-range echo involves both a neural place analysis of the rippled power spectrum and a concurrent neural periodicity analysis: Infrapitch echo permits periodicity analysis to be studied in isolation. It is suggested that neural periodicity analysis follows consistent rules from about 1 Hz well into the pitch range of acoustic iterance.
Pure-tone and FM paradigms in the measurement of frequency discrimination
Authors: Nuetzel J. M. , Bilger R. C. , Rabinowitz W. M. , Trahiotis C.
Published: October 2005

Previous research has shown that the choice of test method can dramatically effect obtained frequency difference limens (Δf). We measured Δf at several frequencies from 125 to 6000 Hz, using both 300-ms pure-tone bursts and tones which were frequency-modulated at 8 Hz. Stimulus levels were approximately 40 dB SL, and 58 experimentally naive subjects were tested with a 4IFC adaptive procedure. The results confirm and extend some of the findings of Moore [Br. J. Audiol. 10, 17 (1976)]. Compared to the pure-tone results, the FM tests revealed less variability, fewer learning effects, and lower Δf's. Discriminability measures across the two conditions were significantly correlated only at and above 2 kHz. Both paradigms revealed significant individual differences and subject-by-frequency interactions. For either paradigm, log Δf can be well described as a linear or a power function of log f, or as a linear function of f½. The results suggest (contrary to some earlier findings) that the FM paradigm may be a superior way to measure the frequency DL, particularly in clinical settings. [Research supported by NIH.]
Comparison of pure-tone with two-tone discrimination
Authors: Feth L. L. , Stover L. J.
Published: October 2005

Previous work from this laboratory has suggested that the discriminability of complementary two-tone complexes is based upon differences in envelope-weighted averages of instantaneous frequency. It seems plausible that pure-tone frequency discrimination and two-tone discrimination may be mediated by a common underlying process. The study was designed to investigate this possibility by comparing the discriminability of complementary two-tone complexes with pure-tone frequency discrimination as signal duration or signal level were varied. Preliminary results indicate either that a common discrimination mechanism is unlikely, or that the envelope-weighted average of instantaneous frequency model should be modified. [Work supported by NIH.]
Rate effects in the detection of short-duration tone glides
Authors: Cullen J. K. , Collins M. J.
Published: October 2005

Previous studies of the detection of short-duration tone glides embedded in broadband noise have shown that glides increasing in frequency are detected at lower thresholds than are counter-part glides which decrease in frequency [Collins and Cullen, J. Acoust. Soc. Am. 63, 469–473 (1978); Nabelek, J. Acoust. Soc. Am. 64, 751–763 (1978)]. We have suggested that this difference in detectability is based, at least in part, in temporal coding initiated by the response characteristics of the cochlear partition. This hypothesis predicts detection differences would vary as a function of rate of frequency change when duration is held constant. In this study, the detection of 5, 10, 20, and 40 ms duration tone glides centered on 2 kHz was investigated as a function of rate. Results show a relatively constant detection threshold for 5 ms rising tone glides across rates. Thresholds for falling tone glides increase exponentially as a function of increasing rate at all durations, while thresholds for rising glides approximate those of falling glides as duration increases. [Work supported by NIH.]
The frequency “pecking order” within musical chords
Authors: Gilliom J. D. , Cline C.
Published: October 2005

Continuing the search for organizational principles important to the perception of part tones within musical chords, the present study explores the effect of intrachordal frequency location. Our paradigm requires an observer to perform a monaural yes-no detection task of a tonal signal within Gaussian noise whose frequency is randomly chosen on each trial from a fixed set of frequencies. A contralateral frequency cue is provided prior to the detection interval on each trial with which the observer can reduce the deleterious effects of this signal frequency uncertainty. In successive experimental conditions of this study, the cue was assigned to each of the possible frequency locations of a three-element musical chord, while monitoring the cue's effectiveness in enhancing detection performance. Shifts in detection performance suggest that specific frequency information derived from part-tones of a musical chord becomes increasingly more accessible the higher the relative frequency location of the part-tone within the chord. This pattern persists even if the relative frequency location of the cue within the chord is randomly varied from trial to trial, preventing any fixed processing strategy on the part of the observer.
Monaural discrimination of phase change as a function of initial phase in two-tone octave complexes
Authors: Müller Carl , Schubert Earl D.
Published: October 2005

A multidimensional scaling study by Hall and Schroeder (1972) suggested that the percept caused by a change in the phase relationship between the two components of an octave complex is dependent only on the amount of change and not on the initial phase within the complex itself. The current study examines that suggestion of uniform perception of phase change. We utilized the paradigm of Nixon, Raiford, and Schubert (1970) to determine the ability of six subjects to detect 30°, 45°, 60°, or 75° changes in the relative phase of the second harmonic of a 250 Hz tone when the initial phase relationship of the octave complex was one of eight standards spaced at 45° intervals. The results showed little support for uniform phase change perception. Analyses based upon theories of aural harmonics, zero-crossing timing, and peak-to-peak timing showed that no one of these theories is sufficient to explain the results. This confirms and extends the early conclusions of Craig and Jeffress (1962) and points to the complex nature of phase processing. [Partially supported by the Knowles, Research Foundation and the Ear Research Institute.]