bluuebunny/crossref_metadata_2025 huggingface dataset:
Vertebral position alters paraspinal muscle spindle responsiveness in the feline spine: effect of positioning duration
Authors: Ge Weiqing , Long Cynthia R. , Pickar Joel G.
Published: October 2005

Proprioceptive information from paraspinal tissues including muscle contributes to neuromuscular control of the vertebral column. We investigated whether the history of a vertebra's position can affect signalling from paraspinal muscle spindles. Single unit recordings were obtained from muscle spindle afferents in the L6 dorsal roots of 30 Nembutal‐anaesthetized cats. Each afferent's receptive field was in the intact muscles of the low back. The L6 vertebra was controlled using a displacement‐controlled feedback motor and was held in each of three different conditioning positions for durations of 0, 2, 4, 6 and 8 s. Conditioning positions (1.0–2.2 mm dorsal and ventral relative to an intermediate position) were based upon the displacement that loaded the L6 vertebra to 50–60% of the cat's body weight. Following conditioning positions that stretched (hold‐long) and shortened (hold‐short) the spindle, the vertebra was repositioned identically and muscle spindle discharge at rest and to movement was compared with conditioning at the intermediate position. Hold‐short conditioning augmented mean resting spindle discharge by +4.1 to +6.2 impulses s−1; however, the duration of hold‐short did not significantly affect this increase (F4,145= 0.49, P= 0.74). The increase was maintained at the beginning of vertebral movement but quickly returned to baseline. Conversely, hold‐long conditioning significantly diminished mean resting spindle discharge by −2.0 to −16.1 impulses s−1 (F4,145= 11.23, P < 0.001). The relationship between conditioning duration and the diminished resting discharge could be described by a quadratic (F1,145= 9.28, P= 0.003) revealing that the effects of positioning history were fully developed within 2 s of conditioning. In addition, 2 s or greater of hold‐long conditioning significantly diminished spindle discharge to vertebral movement by −5.7 to −10.0 impulses s−1 (F4,145= 11.0, P < 0.001). These effects of vertebral positioning history may be a mechanism whereby spinal biomechanics interacts with the spine's proprioceptive system to produce acute effects on neuromuscular control of the vertebral column.
Actions of brain‐derived neurotrophic factor on spinal nociceptive transmission during inflammation in the rat
Authors: Matayoshi Satoru , Jiang Nan , Katafuchi Toshihiko , Koga Kohei , Furue Hidemasa , Yasaka Toshiharu , Nakatsuka Terumasa , Zhou Xin‐Fu , Kawasaki Yasuhiko , Tanaka Nobuyuki , Yoshimura Megumu
Published: October 2005

The aim of the current study was to investigate whether, and if so how, brain‐derived neurotrophic factor (BDNF) acts to develop the spinal sensitization underlying inflammation‐induced hyperalgesia. In spinal cord slice preparations from rats with inflammation induced by complete Freund's adjuvant (CFA), BDNF, but not nerve growth factor (NGF) or neurotrophin‐3 (NT‐3), acted presynaptically to increase the frequency of excitatory miniature EPSCs in substantia gelatinosa (SG) neurones of the CFA‐treated, but not untreated rats, through activation of lidocaine (lignocaine)‐sensitive, TTX‐resistant Na+ channels. This effect was observed in the spinal cord slices of the CFA‐treated rat only 2–4 days after the CFA injection. On the other hand, the number of monosynaptic Aβ afferent inputs to the SG significantly increased 1 week after the onset of the inflammation, and this increase was significantly suppressed by treatment with anti‐BDNF antiserum administered 1 day before and just after the CFA injection. In addition, the treatment with anti‐BDNF antiserum significantly attenuated the CFA‐induced hyperalgesia and/or allodynia. These findings, taken together, suggest that BDNF, which is considered to be released from the sensitized primary afferents, increases the excitability of SG neurones through its action on the presynaptic terminals. BDNF may thereafter induce monosynaptic Aβ afferents to the SG, thereby developing hyperalgesia and/or allodynia during inflammation.
Effect of hydration on interstitial distribution of charged albumin in rat dermis in vitro
Authors: Wiig Helge , Tenstad Olav , Bert Joel L.
Published: October 2005

At physiological pH, negatively charged glycosaminoglycans in the extracellular matrix may influence distribution volume of macromolecular probes, a phenomenon of importance for hydration of the interstitium and therefore for body fluid balance. We hypothesized that such charge effect was dependent on hydration. Human serum albumin (HSA) (the pH value for the isoelectric point (pI) = 4.9) was made neutral by cationization (cHSA) (pI = 7.6). Rat dermis was studied in vitro in a specially designed equilibration cell allowing control of hydration. Using a buffer containing labelled native HSA and cHSA, the distribution volumes were calculated relative to that of 51Cr‐EDTA, an extracellular tracer. During changes in hydration (H), defined as (wet weight – dry weight) (dry weight)−1), the slope of the equation describing the relationship between extracellular fluid volume (Vx) (in g H2O (g dry weight)−1) and H (Vx= 0.925 H + 0.105) differed significantly from that for available volumes of cHSA (Va,cHSA= 0.624 H – 0.538) and HSA (Va,HSA= 0.518 H – 0.518). A gradual reduction in H led to a reduction in difference between available volumes for the two albumin species. Screening the fixed charges by 1 m NaCl resulted in similar available and excluded volumes of native HSA and neutral cHSA. We conclude that during gradual dehydration, there is a reduced effect of fixed negative charges on interstitial exclusion of charged macromolecules. This effect may be explained by a reduced hydration domain surrounding tissue and probe macromolecules in conditions of increased electrostatic interactions. Furthermore, screening of negative charges suggested that hyaluronan associated with collagen may influence intrafibrillar volume of collagen and thereby available and excluded volume fraction.
Differential targeting and functional specialization of sodium channels in cultured cerebellar granule cells
Authors: Osorio Nancy , Alcaraz Gisèle , Padilla Françoise , Couraud François , Delmas Patrick , Crest Marcel
Published: October 2005

The ion channel dynamics that underlie the complex firing patterns of cerebellar granule (CG) cells are still largely unknown. Here, we have characterized the subcellular localization and functional properties of Na+ channels that regulate the excitability of CG cells in culture. As evidenced by RT‐PCR and immunocytochemical analysis, morphologically differentiated CG cells expressed Nav1.2 and Nav1.6, though both subunits appeared to be differentially regulated. Nav1.2 was localized at most axon initial segments (AIS) of CG cells from 8 days in vitro DIV 8 to DIV 15. At DIV 8, Nav1.6 was found uniformly throughout somata, dendrites and axons with occasional clustering in a subset of AIS. Accumulation of Nav1.6 at most AIS was evident by DIV 13–14, suggesting it is developmentally regulated at AIS. The specific contribution of these differentially distributed Na+ channels has been assessed using a combination of methods that allowed discrimination between functionally compartmentalized Na+ currents. In agreement with immunolocalization, we found that fast activating–fully inactivating Na+ currents predominate at the AIS membrane and in the somatic plasma membrane.
Intensity DLs as a function of stimulus duration
Authors: Florentine Mary , Buus Søren
Published: October 2005

Intensity DLs (10*log[(I + ΔI)/I]) were measured as a function of stimulus duration for tones at 250, 1000, and 8000 Hz. At each frequency three levels were tested: 85, 65, and approximately 40 dB SPL. Ten or eleven stimulus durations ranging from 2 ms (4 ms at 250 Hz) to 2 s were tested. An adaptive two-alternative forced-choice procedure with feedback was used. The rise and fall times were 1 ms and the interstimulus interval was 250 ms. Results for three young normal listeners show that DLs decrease with increasing duration up to at least 2 s, except at 250 Hz. At 250 Hz, the maximum integration time is between 0.5 and 1.0 s. In a double logarithmic plot of DL (in dB) versus duration the data are well described by straight lines (r < − 0.97). The slope of these lines is approximately independent of level, but appears steeper at 1000 Hz (slope≈ −0.38) than at 250 Hz (slope≈ −0.29) and 8000 Hz (slope≈ − 0.26). At all three frequencies, the slopes are shallower than the slope of −0.5 predicted by an optimum detector. [Supported by NIH.]
Intensity discrimination of pure tones is not a monotonic function of sensation level for frequencies above 6 kHz
Authors: Long Glenis R. , Cullen John K.
Published: October 2005

Some recent studies of intensity discrimination at high frequencies have reported that measures of intensity discrimination are nonmonotonically related to sensation level (SL) for frequencies between 6 and 10 kHz [Carlyon and Moore, J. Acoust. Soc. Am. Suppl. 1 73, S93 (1983); Cullen and Long, Abstr. Seventh Midwinter Research Meeting of ARO, 5 (1984)]. At these frequencies, difference limens estimated from amplitude modulation detection and pulsed tone discrimination are largest for stimuli near 30 to 40 dB SL. We have extended our studies to 14 kHz and obtained a more detailed characterization of this nonmonotonicity by measuring amplitude modulation detection thresholds for stimuli in 5-dB steps between 10 and 65 dB SL. Our data indicate that the larger difference limens reported by Florentine [J. Acoust. Soc. Am. 74, 1375–1379 (1983)] for high-SL high-frequency signals are found when the frequencies tested are near the upper limit of a subject's hearing. [Supported, in part, by Kam's Fund and Eye, Ear, Nose, and Throat Foundation of New Orleans.]
Detection of tones in the absence of external masking noise. II. A reconsideration of the relation between d′ and the ISO standard
Authors: Wier Craig C. , Skalabrin Terri
Published: October 2005

Watson, Franks, and Hood [J. Acoust. Soc. Am. 52, 633–643 (1972)] investigated the detectability of tones in the absence of external masking noise in normally hearing listeners and compared their data with the ISO standard for audiometric zero. They concluded that the ISO standard represented thresholds roughly equivalent to d′ = 1.0 performance. Watson and his colleagues used stimuli 150 ms in duration. Pure-tone temporal-integration data show that longer signal durations yield lower threshold estimates up to a frequency-dependent limit. The ISO-standard data were collected with signals designed to exceed the limits of temporal integration. Psychometric functions for tone detection in quiet are steep; consequently, when longer duration signals are used, a small threshold change of the magnitude expected from temporal integration would alter the performance relation suggested by Watson et al. Re-evaluation suggests that the ISO standard probably represents a performance level greater than d′ = 2.0. [Work supported by NINCDS.]
The coupling of sub-audio amplitude and frequency modulafions and the perception of spectral envelope characteristics
Authors: McAdams Stephen , Rodel Xavier
Published: October 2005

One possible cue for the relative perceptual invariance of a resonant source with pitch change is the tracing of its spectral envelope by its modulating frequency components. This tracing would reduce the ambiguity concerning the resonant structure of the source at higher F0's where the formants are not filled by partials. This paper investigates the role that spectral tracing (FM-induced AM) plays in the perception and identification of vowels with high F0. Two five-formant vocal spectra were selected to give nearly identical spectra when not modulated. When modulated by vibrato, a single component differed in the sign of its amplitude-frequency slope while the behavior of the rest was identical in the two cases. At larger frequency modulation depths, a difference in vowel quality is perceived. The threshold depth at which the stimuli were distinguished and the threshold depth for identification were determined. Discrimination thresholds were lower than identification thresholds. The discrimination thresholds for sine tones with amp-freq slopes of opposite sign were also determined, and were found to be greater than the thresholds for the complex tones. The results will be discussed in terms of intensity discrimination results and of recent work in spectral profile analysis.
Neonatal development of frequency difference limens in chickens
Authors: Gray Lincoln , Rubel Edwin W.
Published: October 2005

Young chickens will suppress their regular peeping when they hear a change in the frequency of pulsing pure tones. The duration of this peep suppression grows with increasing amounts of frequency change. Various adaptive tracking procedures can thus use this response to estimate frequency difference limens in neonatal chickens. These estimates in chickens as young as 4 days of age are close to others available in the literature from mature subjects. Despite large variability in the results from these “staircases,” frequency difference limens generally decrease by approximately one percent over the first 4 days of post-natal life. As expected from human studies, variability in this discrimination task is greater than previously reported in a comparable detection task [L. Gray and E. W. Rubel, J. Acoust. Soc. Am. Suppl 1 71, S31 (1983)]. In conclusion, there is a significant increase in responsiveness to small changes in the frequency of pure tones as animals mature over the first few post-natal days. [Work supported by NIH.]
Frequency DL duration functions and estimated excitation-pattern slopes in normal and hearing-impaired listeners
Authors: Freyman Richard L. , Nelson David A.
Published: October 2005

When the frequency DL is plotted as a function of tonal duration, an abrupt change in the slope of the DL duration function is often observed [Liang and Chistovich, Soy. Phys. Acoust. 6, 75–80 (1961)]. Their explanation was that the DL is normally limited by the auditory filter bandwidth, but when the signal is shortened so that its bandwidth is broader than that of the auditory filter, the broader spectral bandwidth of the signal determines the size of the frequency DL. We tested a similar hypothesis using excitation-pattern slopes and spectral slopes rather than bandwidths, and extended the hypothesis to predict DLs from hearing-impaired listeners. DL duration functions and estimated excitation-pattern slopes were obtained from five normal-hearing and six hearing-impaired listeners. The break points in DL duration functions predicted by equating excitation-pattern and signal spectral slopes were in close agreement with the observed break points. As predicted by their more gradual excitation-pattern slopes, the break points occured at shorter durations, or not at all, in the hearing-impaired subjects. [Work supported by NINCDS Grants NS15451 and NS12125.]
Implications of level-dependent auditory filtering for the discriminations of complex stimuli
Authors: Turner Christopher , Cacace Anthony , Trees Debra
Published: October 2005

Many types of masking experiments have suggested that the auditory filter does not remain constant in shape as a function of input level. Performance on discrimination tasks using spectrally complex stimuli might be expected to be critically dependent upon changes in filter shape. Each stimulus in the present discrimination task consisted of a bandpass noise and a less intense pure tone at an adjacent frequency region. Discrimination pairs differed only in the amplitude of the tonal components. The subject's task was to indicate the stimulus containing the more intense tonal component. The intensity level of the noise band relative to the tonal component remained constant as the subject performed the discriminations over a 65-dB range. Data from normal-hearing subjects demonstrated that, for certain combinations of noise and tone, performance becomes considerably poorer at high overall stimulus levels. These results support the concept of a broadened filter at high input levels, and demonstrate that this level-dependent filter shape may have consequences for discrimination of complex stimuli. Implications for normal-hearing and hearing-impaired listeners will be discussed. [Work supported by Sigma Xi.]
Individual differences in pattern discrimination by naive Usteners
Authors: Leek M. R. , Colleran E.
Published: October 2005

Experimenters have frequently noted large individual differences in listeners' abilities to discriminate auditory patterns differing only in the frequency of one pattern component. Whereas some subjects require weeks of practice with large pattern differences, others can make fine discriminations almost immediately. To further characterize such subject-dependent differences in performance, we investigated pattern discrimination by listeners with only minimal paychoacoustic experience. Since most naive listeners can detect a frequency change if the target component is much longer than the other pattern components, we measured the target tone duration required for correct discrimination 71% of the time in a standard/2AFC procedure, for five levels of target frequency difference (Δ ∫) ranging from 18 to 92 Hz. Nine of the ten pattern components were 45 ms in duration, while the target tone duration varied according to an adaptive track. The target tone (920 Hz) was always the second pattern component. The nine other tones, with frequencies between 500 and 1500 Hz, were randomly ordered on every trial. Threshold durations were estimated from adaptive tracks for each Δ ∫. Generally longer target tone durations were required to discriminate small Δ ∫'s than for larger frequency differences, paralleling the effects of duration on frequency discrimination of brief tones in isolation. Each listener clearly fell into one of two nonoverlapping groups: those with high duration thresholds for all Δ ∫'s tested, and those who consistently required much shorter target tone durations.
Critical bands in the perception of speech signals
Authors: Celmer Robert D. , Bienvenue Gordon R.
Published: October 2005

Current auditory theory suggests a major role for the phenomenon of critical bands in hearing. The critical band is, essentially, a filtering process whereby sound is categorized according to its frequency content. While some empirical evidence suggests that the critical band may serve in the analysis of speech, this has never been directly demonstrated. In the present study, digital signal processing techniques have been developed for altering available recorded speech materials so that the frequency resolution available in the resultant stimuli may be controlled. Tapes have been produced wherein the frequency resolution is limited to narrower than, equal to, and wider than one critical band and these tapes have been used in intelligibility testing with normal listeners. The critical bandwidths of the subjects have been measured by an independent technique. By the use of the above recordings, it has been possible to test directly the hypothesis that the critical band is an essential element in auditory speech intelligibility. [Work supported in part by Naval Sea Systems Command.]
Fricative-vowel coarticulatory effects in Arabic
Authors: Bassich Celia J. , Yeni-Komshian Grace H. , Soli Sigfrid D.
Published: October 2005

Using LPC analysis, an investigation of anticipatory vowel coarticulation was made of 100-ms segments of Arabic voiceless fricatives (/h, x, ∫, and s/) spoken in isolation and in three prevocalic contexts (/ɑ, i, and u/) by three native speakers. The degree of coarticulation for each prevocalic fricative segment was determined by assessing both the amount of spectral change from the isolated production, and the relationship of prevocalic fricative peaks to vowel formats. Strong coarticulation was observed for all speakers in all three vowel contexts for the pharyngeal fricative /h/, while minimal coarticulatory effects were present for the dental fricative /s/. Vowel specific trends were evident for the palatal /∫/ and velar /x/ fricatives: strong coarticulation was seen for /xi/, /xu/, /∫i/ and/ ∫ɑ/ and not the remaining utterances. Individual differences were evident with respect to degree of coarticulation. The three speakers behaved similarly for only three of the 12 fricative-vowel utterances. Results are discussed in terms of the articulatory compatibility principle. Present address: Biosciences Lab., 3M Center, St. Paul, MN.
Variability characteristics of segment and ratio measures of timing in normal and neurogenically disordered speakers
Authors: Weismer Gary , Fennell Ann M.
Published: October 2005

The variance of speech timing measures has been used by a variety of investigators as in index of speech motor control. Children tend to have larger variances than adults for segment durations as do some adult dysarthrics compared to neurologically intact adults. The implication is that the larger variances reflect functional immaturity and deficits in the speech mechanisms of children and neurogenically involved adults, respectively. The present report deals with variance characteristics of segment and ratio measures of timing in normal and dysarthric speakers. Two interesting results are (1) fast speaking rate increases the variability of temporal ratios in all normal subjects, and in some dysarthric subjects, and (2) increased utterance length is associated with increased timing variability in spastic dysarthrics. These results are discussed relative to organizational and biomechanical differences between conversational and fast speaking rates, and as they may apply to models of dysarthria. [Work supported by NIH.]
When (if ever) does speaking rate become an essential variable in speech production
Authors: Fennell Ann M. , Weismer Gary
Published: October 2005

In a previous paper [G. Weismer, J. Acoust. Soc. Am. Suppl. 1 73, S65-S66 (1983)] we presented evidence that conversational and very fast speaking rates have virtually identical relative timing characteristics, thus supporting the notion of relative timing as a nonessential variable in speech production. In the present paper we replicate these findings and extend the analysis to the case of very slow speaking rates. In addition, measures of fundamental frequency contour and formant transition rate are studied to determine how their form may be altered by changes in speaking rate. Because slow speaking rates are often used as a strategy in rehabilitation of various speech disorders, it is important to know if the form of various vocal tract outputs is disrupted by unusually slow rates. Recent biomechanical studies indicate that slow rates may require unique control strategies, thus implying that a critical value of the nonessential variable speaking rate may be demonstrated experimentally by requiring normal speakers to produce speech at very slow rates. [Work supported by NIH.]
Some effects of speaking rate on spectral and temporal characteristics of American English vowels
Authors: Gopal H. S. , Syrdal A. K.
Published: October 2005

The effects of speaking rate on spectral and temporal characteristics of American English vowels were studied. Five women and five men, native American English speakers without strong regional dialects, produced the carrier phrase sentence “I said hVd again” at slow, conversational, and fast rates. Twelve vowels, /i, ɪ ey, ɛ, æ ɜ, ʌ ɑ, ɔ, ow, ʊ u/ were studied in /hVd/ context. Acoustic analyses were performed using the SPIRE speech analysis programs on a LISP machine. Recordings were digitized at a 16-kHz sampling rate and low-pass filtered. Spectral measurements included fundamental frequency and the first four formants. Temporal measurements made were vowel duration, syllable duration, and closure duration. Durations, duration differences, and rate related changes were quite systematic within and across vowel types. Results indicated that the durations of long vowels and diphthongs were compressed more than that of short vowels as speaking rate increased. Spectral differences were relatively small across speaking rates. The utility of duration as well as spectral information for vowel classification will be discussed. [Work supported by NIH and UTD research grants, and performed in part at the Research Lab. of Electronics, MIT.]
Fundamental frequency patterns in simple sentances of Canadian French
Authors: Eady Stephen J.
Published: October 2005

This study investigated patterns of voice fundamental frequency (F0) in the production of simple sentences of Canadian French, to determine how these patterns are influenced by a number of linguistic and nonlinguistic factors. Twenty phonetically balanced sentences were produced by 12 adult speakers (six males and six females) and were analyzed with respect to the peak values of F0 for preselected key words (i.e., the F0 topline). The results show that isolated sentences of Canadian French are characterized by a definite declination pattern, which is similar (but not identical) to that reported for comparable sentences of American English [W. E. Cooper and J. Sorensen, Fundamental Frequency in Sentence Production (1981)]. Contrary to previous findings, however, the topline pattern for simple French sentences is not significantly influenced by the phonetic composition of the measured syllables; nor does sentence length have a significant effect on the initial F0 peak of a French sentence. Moreover, speakers having different F0 ranges (i.e., males versus females) do not differ in the shape they give to the F0 topline of a French sentence. The implications of these findings for a model of fundamental frequency in speech production will be discussed. [Work supported by BRS Grant RR-05596 to Haskins Laboratories and by the Social Sciences and Humanities Research Council of Canada.]
Motor vehicle noise measurements, regulations, and standards: A European viewpoint
Authors: Martin Jacques
Published: October 2005

The “measurement of noise emitted by passenger cars under conditions representative of urban driving” is the subject of a draft international standard prepared by Working Group 8 of ISO/TCA3/SC1. Balloting on DIS 7188.2 has now been completed and further action can be expected soon. The author of this paper will present a European viewpoint on motor noise standardization from his perspective as Chairman of WG8. He will also report on the progress of discussions in Brussels for EEC and in Geneva for ECE from his perspective as a Technical Expert for the French Government.
Sound propagation phenomena and source motion effects in the measurement of motor vehicle noise
Authors: Daigle G. A.
Published: October 2005

At short ranges the phenomena relevant to the propagation of motor vehicle noise include inverse square law, interference between direct and ground reflected waves, the finite impedance of the ground, refraction, and turbulence. The interference between direct and reflected waves is a rapidly varying function of receiver distance and height from the source. If the ground has a detectable finite acoustic impedance a shadow region is produced which is penetrated at low frequencies by a ground wave. For ground having impedance discontinuities a diffracted wave originates at the interface. Strong wind and temperature gradients close to the ground produce a refractive shadow that is penetrated by a creeping wave. Wind and temperature fluctuations (turbulence) cause sound energy to be redirected by scattering and enhance sound pressure levels in the vicinity of acoustic shadow regions. In addition to the sound propagation phenomena, mechanisms associated with the moving vehicle cause variability in motor vehicle noise measurements. Experiments designed to separate the causes of this variability are discussed. The source of variability for moving vehicles can be either refraction in the turbulent wake of a moving vehicle or possibly the complicated diffraction pattern around a vehicle that changes rapidly with frequency.
Possible use of acoustic intensity measurement in standard tests of vehicle noise
Authors: Hickling Robert
Published: October 2005

Existing standard tests of motor vehicle noise, such as passby tests, are based on sound pressure measurements with single fixed-location microphones. Recent developments in two-microphone acoustic-intensity techniques, and in instrumentation, permit the practical measurement of the sound power of vehicles and of components, such as engines. This can be performed in a normal test environment; a special acoustical facility such as an anechoic chamber or a reverberation room is not required. Sound power, which is a single-number measure of the total output of a noise source, appears better suited to determining the overall effect of a vehicle on community noise. Also sound power is usually measured indoors, thereby avoiding scheduling delays due to bad weather and the inherent variability in the data associated with outdoor testing. Good repeatability (i.e., a standard deviation less than 5% or 0.2 dB) has been demonstrated in the measurement of the sound power of a medium-duty truck, using acoustic intensity methods in an indoor test. Similar repeatability has been demonstrated in the measurement of the sound power of an engine for a heavy-duty truck. These and other advantages and disadvantages of the use of acoustic intensity measurement methods for standard tests are discussed in the presentation.
Critical-band-weighted linear prediction of speech
Authors: Hermansky Hynek , Hanson Brian A. , Wakita Hisashi
Published: October 2005

Standard linear predictive (LP) analysis does not represent several important properties of the human auditory system, such as decreasing spectral resolution with frequency and nonlinear intensity-loudness characteristics. The proposed technique, perceptually based LP analysis, introduces nonlinear frequency and spectral amplitude weighting by approximating critical-band-weighted speech spectra using spectral transform LP modeling [H. Hermansky, H. Fujisaki, and Y. Sato, Proc. ICASSP 1983, pp. 777–780]. The critical-band spectral weighting simulates the nonlinearity of human auditory frequency resolution, the amplitude axis root spectral transform simulates Stevens' intensity-loudness power law, and the LP modeling emphasizes the perceptual importance of spectral envelope peaks. Experiments show that the proposed technique yields more consistent estimates of perceptually important spectral peaks and provides an efficient parametric representation of speech.
Elimination of an artifact from narrow-band digital speech spectrograms
Authors: Neuburg Edward P.
Published: October 2005

There is an unpleasant artifact in narrow-band spectrograms that is caused by filtering. If the filter straddles the trough between two pitch bars of equal amplitude, even if the bars lie out in the skirts of the filter, they beat together causing spots in the spectrogram (at the fundamental frequency). Where pitch bars have small slopes this sometimes gives rise to a look of “beads-on-a-chain” in the trough. At high slopes it can break up the pitch bars, producing apparent lines that may be orthogonal to the pitch bars. The artifact can be eliminated by smoothing in the direction of the pitch bars. This direction can be found during calculation of digital (e.g., FFT) spectrograms. Nearby spectra (sections) of voiced speech are essentially identical, except that one is a “stretch” of the other. The stretch that makes them the most similar specifies the direction of the pitch bars at every frequency. Local smoothing of the picture in this direction eliminates the artifact without loss or smearing of speech information. Spectrograms of speech with and without smoothing will be shown. Directional smoothing may also be useful in enhancing noisy speech.
Vocal tract area functions from autoregressive analysis of two-point acoustic data
Authors: Naimi Fariborz , Milenkovic Paul , Muller Eric M.
Published: October 2005

It is well known that the frequencies of the low-order driving point impedance poles and zeros of the vocal tract can be used to determine a smoothed representation of the vocal tract area function. The impedance poles are congruent with the vocal tract formants; the pole frequencies are specified by the location of peaks in the speech spectrogram. The impedance zero frequencies are indirectly related to formant bandwidths. The bandwidths, however, are difficult to accurately measure from speech. A method is presented for estimating vocal tract impedance zero frequencies directly as the peaks of the transfer function relating the acoustic speech signal to the acceleration signal from a transducer taped to the skin of the neck at the thyroid notch. This transfer function is estimated from pressure and acceleration signals using an autoregressive technique. Area function reconstructions derived from estimated pole and zero frequencies from human speech are presented. [Work supported by NIH.]
Influence of compliant layers on radiation from ribbed plates
Authors: Berkman E. F. , Smith P. W. , Haberman R.
Published: October 2005

It is understood that compliant layers having a relatively low impedance relative to the specific acoustic impedance of the fluid will reduce the radiation efficiency of vibrating structures. It is also understood (from power balance arguments) that the application of any compliant treatment onto a finite panel may be ineffective in reducing acoustic radiation unless the total damping of the panel is dominated by mechanisms other than radiation. The consequences of applying compliant, nominally radiation-reducing treatments to large, effectively infinite, ribbed structures has not been so clear. We examine this problem and compute the actual radiation reduction as a function of both (a) a measure of the nominal radiation-reduction effectiveness of the treatment and (b) dissipation in the structure. Changes in spatial characteristics of the radiated field are also examined.
Power flow in complex one-dimensional structures using Green's functions
Authors: Tucker A. J. , Clark J.
Published: October 2005

The measurement of power flow in one-dimensional structures using two-point intensity methods becomes difficult when the structures consist of finite components with different loss factors. If the loss factors are large, the power flow is more easily measured; however, for structural components with small loss factors, the nearfield effects of attachments and ends, high-energy densities, and measurement bias errors hamper the measurement and interpretation of the power flow. The existence of closed-form Green's functions for one-dimensional systems and the ability to construct closed-form Green's functions for systems with inhomogeneities and mutual coupling allow one to calculate closed-form exact solutions for the power flow. From these solutions one can interpret and gain physical insight into the parameters controlling the power flow. Also these solutions permit one to simulate experimental measurement techniques and to assess the aforementioned difficulties. Examples will be illustrated for complex coupled systems consisting of strings with localized and distributed damping. Extensions to other types of structures will be indicated.
Vibration response of building structures, including damage due to subsonic aircraft noise
Authors: Cuschieri J. M.
Published: October 2005

The damage assessment of windows and buildings in the vicinity of airports is presently related to the overpressure created by sonic booms due to supersonic aircraft. However, in some instances damage may also result due to overpressures created by low-flying subsonic commercial aircraft, in houses which are directly underneath the flight path. In the latter case the buildings and windows are exposed to a much longer pressure transient, lasting a few seconds, and the damage results from the repetitive maximum cyclic stresses rather than the impulsive loading as in the case of sonic booms. Thus the analysis for damage can best be performed by considering the response of the structural or window panel to a low-frequency broadband noise excitation. The level of the excitation is dependent on a number of parameters, including atmospheric conditions, types of aircraft, and direction, and course changes right after takeoff. Assuming the structures to behave linearly, the maximum level of stress induced, and an assessment of damage, can then be obtained from consideration of excitation pressure spectrum and response spectrum.
Experiments with a digital bow
Authors: Weinrich Gabriel , Caussé René
Published: October 2005

Relatively few direct experiments on the bow-string interaction have been done in the past because the exact velocity dependence of the bow force is very difficult to measure, let alone control. We are attacking this problem by constructing a computer-operated “equivalent bow.” The bowing point of a (metal) string is placed in a strong localized magnetic field, so that an electric current passing through the string gives rise to a force applied at that point. This current is, in turn, controlled in real time by a computer making its decisions on the basis of the instantaneous velocity of the string, as measured by the digitized output of an appropriate sensor. By programming the function that relates the current to the velocity of the string, we in effect control the equivalent frictional characteristic of the bow-string interaction. More complex dynamical models can also be realized. [Work supported in part by NSF.]
String inharmonicity and piano tuning
Authors: Heetveld Vincent , Rasch Rudolf A.
Published: October 2005

Inharmonicity is a well-known property of the stiff strings as used in the modern piano. Effects on piano tuning (e.g., the stretched octave) have been suggested but never fully investigated. We have measured the inharmonicities of the strings of a medium-sized grand piano. The measured inharmonicities were in excellent correspondence with the predictions by formula from the physical properties of the strings. Six models, differing in three pairs of assumptions, were developed for describing the effects of the inharmonicity on the tuning of the piano and on the beat frequencies used when tuning. The correspondence between the model predictions and the actually applied tuning could be used to test the validity of the assumptions. One of the surprising outcomes was that the fact that higher harmonics of lower strings beat with lower harmonics of higher strings (which have, as a rule, higher inharmonicity) cancels out a part of the effects of inharmonicity on beat frequency.
Mechanical response of guitars
Authors: Popp John , Rossing Thomas D.
Published: October 2005

The mechanical response of a guitar is characterized by a series of resonances and antiresonances which are related to the normal modes of vibration of the top plate, the back plate, and the enclosed air. The response depends on the manner in which the guitar is driven and especially the way in which it is supported. We compare the response of classical and folk guitars freely supported (with rubber bands) and with the ribs clamped as well as under other conditions. The resonances at low frequency compare favorably to the predictions of two-mass and three-mass models.
Influence of baffle conditions on transient radiation
Authors: Guyomar Daniel , Powers John
Published: October 2005

The influence of assumed baffle conditions (rigid, free-space, and soft) on the transient field radiated from a planar surface are investigated. The emitter is arbitrarily shaped and a common time excitation is assumed for all points on the emitter. The technique requires that only the normal derivative of the surface excitation be known. The three baffle conditions differ in the introduction of a specific directivity factor and a convolution term. The computation of the fields is done with a time extension of the angular spectrum approach to diffraction. The spatial spectra of the fields for the three baffle conditions can be interrelated. From this model, propagation is seen to be a time-varying low-pass spatial filter. The method is valid for arbitrary surface shapes, arbitrary time excitations, and arbitrary propagation distances. The techniques allows time-efficient computer solution that are rapidly convergent. Computer simulations including a circular piston, a rectangular source, and a truncated Gaussian are presented.
Application of high-resolution processing to range and depth estimation using ambiguity function methods
Authors: Fizell Richard G.
Published: October 2005

For many acoustic environments a target's acoustic field incident on a hydrophone array segment is not representable by a plane wave, but is a function, generally, of three coordinates: range, depth, and bearing. In these cases a conventional beamformer, which is designed to detect plane waves, cannot localize the target accurately. Techniques have been developed recently to exploit the complexity of the field to estimate the source location coordinates by correlating the received field on the array with accurate replicas of the acoustic field, derived from knowledge of the environment. The potential utility of such techniques has been demonstrated in determining range and depth for simulated high-SNR signals. In this paper, however, they are shown to exhibit excessive sidelobes for low SNR. To alleviate this problem, two high-resolution techniques, the Maximum Likelihood Method (MLM I and “Alternate Orthogonal Projection” (AOP), or linear predictor, are applied to the simulated case of one target in white noise in a Pekeris environment. MLM is seen to produce stable main peaks which localize targets precisely with low sidelobes, while AOP is shown to be unstable in the presence of random noise and to produce false peaks even when the noise fields are stable.
Nonlinenr and non-Gaussian ocean acoustic ambient noise processes
Authors: Wilson Gary R. , Brockett Patrick L.
Published: October 2005

The bispectrum of several measured ocean acoustic ambient noise processes was estimated and used to test for the linearity and Gaussianity of the processes. A linear process has a constant bispectrum, while a Gaussian process has a zero bispectrum. Both linearity and Gaussianity could be easily rejected for several common ambient noise processes, even though in some cases the processes tested to be univariate Gaussian. These results suggest that autoregressive models, since they are linear models, may not be the most appropriate models for ocean acoustic ambient noise. Some possible explanations for the causes of the observed nonlinear behavior will be suggested. [Work supported by the Office of Naval Research, Code 411.]
Trading relations in the perception of /r/-/l/ by Japanese learners of English
Authors: Underbakke Melva , Strange Winifred , Polka Linda
Published: October 2005

Native English speakers show a trading relation and perceptual integration of a temporal cue (F1 transition duration) and spectral cues (F3 and F2 onset and transitions) differentiating the liquids /r/-/l/ [L. Polka and W. Strange, J. Acoust. Soc. Am. Suppl. 1 73, S53 (1983)]. To investigate the effects of linguistic experience on these perceptual phenomena, native Japanese speakers learning English completed forced-choice identification and oddity discrimination tasks, using two synthetic /rak/-/lak/ series in which the temporal and spectral cues were varied orthogonally. Identification functions of Japanese who could consistently label the /r/-/l/ series showed a trading relation (a predictable shift in the identification category boundary) and perceptual integration of temporal and spectral cues. Discrimination of pairs differing on both cues was significantly better than spectral-cue-alone pairs only when the combination of cue values facilitated phonemic differentiation. Preliminary results with less advanced Japanese English learners showed no advantage in discrimination performance of two-cue pairs over one-cue pairs, suggesting that the perceptual integration of cues is a function of language-specific phonetic processing. [Work supported by NIMH.]
F1-cutback interactions in the perception of voicing contrasts
Authors: Pastore Richard E. , Wielgus Virginia G. , Szczesiul Rosemary
Published: October 2005

A number of investigators have identified both VOT and F1 cutback as major cues for voicing contrasts. At recent meetings we have presented evidence that sinusoidal analogs to isolated F1-cutback stimuli are perceived in a relatively discrete fashion with category boundaries corresponding to those found for synthetic speech continua. In contrast to nonspeech analogs to VOT continua (both tone-onset-time for stationary and nonstationary stimuli, and noise-onset-time for noise-buzz stimuli), the sinusoidal analogs to F1 cutback exhibit a dependency of the category boundary on spectral frequency. Furthermore, the category boundary locations for the F1-cutback analogs correspond to the voicing contrast boundary locations for speech stimuli. Our current research examines the perception of the F1-cutback analog presented in conjunction with various configurations of tone-onset-time and noise-onset-time continua. In all current conditions, the degree of F1-cutback analog and the relative onset asynchrony in the F2 frequency region are equivalent. The results will be discussed in terms of the similarities and difference in parameter dependencies for these nonspeech stimuli and voicing contrasts for speech stimuli.
Integral processing in phoneme perception
Authors: Mullennix John W. , Tomiak Gail R. , Sawusch James R.
Published: October 2005

To investigate the extent and locus of integral processing occurring in speech perception, a speeded classification task was utilized with a set of noise-tone analogs of the fricative-vowel combinations [fæ], [shæ], [fu], and [shu]. Subjects were instructed to either treat the stimuli as speech or nonspeech. Results showed that within a nonspeech mode, noise and tone identity were processed in a separable manner. However, in a speech mode, the same stimuli were asymmetrically integral. Utilizing the same task, two sets of naturally spoken fricative-vowel syllables were tested: one which contained coarticulatory information, and one which did not. Results for these stimuli showed that the noncoarticulated syllables also exhibited asymmetric integrality, while the coarticulated stimuli showed symmetric integrality. These results support an interpretation of phonetic coding where knowledge of coarticulation (or its acoustic consequences) is a basic element of speech mode perception. Furthermore, the use of this knowledge in speech coding is mandatory, even in situations where the stimuli contain no coarticulatory information. [Work supported by NINCDS.]