摘要:

These experiments investigated whether perceptual cueing plays a role in the ‘‘unmasking’’ effects which have been observed in forward masking for narrow‐band noise maskers and brief signals. The forward masking produced by a 100‐Hz‐wide noise masker at a level of 60 dB SPL was measured for a 1‐kHz sinusoidal signal with a raised‐cosine envelope and a duration of 10 ms at the 6‐dB‐down points, both for the masker alone, and with various components added to the masker (and gated synchronously with the masker). Unmasking was found to occur even for components which were extremely unlikely to produce a significant supression of the masker: these included a 75‐dB SPL 4‐kHz sinusoid, a 50‐dB SPL 1.4‐kHz sinusoid, a noise low‐pass filtered at 4 kHz with a spectrum level of 0 dB, and a noise low‐pass filtered at 4 kHz with a spectrum level of 20 dB presented in the opposite ear to the masker‐plus‐signal. It is concluded that perceptual cueing can play a significant role in producing unmasking for brief signals following narrow‐band noise maskers, and that it is unwise to interpret the unmasking solely in terms of suppression.

ISSN:0001-4966    

DOI:10.1121/1.391738

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

A series of experiments was conducted to examine the influence of contrastive stress on intonational patterns of duration and fundamental voice frequency (F0). In a preliminary study, intonational patterns in spontaneous speech were compared with the patterns in oral reading of the transcribed spontaneous material. In both circumstances, a general declination ofF0peaks throughout the course of a sentence was not regularly observed, contrary to earlier findings with oral reading of isolated sentences. Two experiments were then conducted to examine the possibility that the general absence of declination observed here might be due to the influence of sentence focus, following previous results from Swedish showing that declination was not observed consistently in isolated sentences until after the site of focus. In experiment 1, we found no evidence of this restriction on declination in the oral reading of English declaratives. Declination was observed both before and after the focused item in a sentence. Furthermore, our analyses revealed that focus (as manifested by contrastive stress) is generally accompanied by an increase in duration on the focused word and by a sharp drop inF0following the focused item. In experiment 2, these effects were replicated and extended using longer sentences. In both experiments, the influence of focus was strictly localized to the site of focus in the case of duration, but notF0. The results for both duration andF0indicate that the influence of focus assignment on these attributes varies systematically as a function of the focus location in the sentence. Finally, the combined elongation effects for focus and utterance‐final lengthening were less than would be predicted by an additive model, suggesting the operation of an expandability constraint on segmental lengthening in speech production.

ISSN:0001-4966    

DOI:10.1121/1.392372

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

Two algorithms, termed schematic and naturalistic, for generating intonation contours in an English text‐to‐speech system are compared by eliciting preference judgments from a total of 21 subjects. The major problem for both algorithms, but especially for the schematic algorithm, has to do with accent assignment and with the determination of the intonation phrase rather than with the phonetic realization of accent through manipulation ofF0. Due to parser errors, phrase boundaries are incorrectly identified in 30% of the sentences used in the three experiments. Moreover, the naturalistic algorithm uses a grammatical part‐of‐speech hierarchy which ranks nouns higher than verbs. Therefore, incorrect classification of verbs as nouns (the major classification error) results in an unintended accent. The results indicate that accent assignment and phrase determination are the primary areas requiring improvement in order to further increase the naturalness of synthetic speech intonation.

ISSN:0001-4966    

DOI:10.1121/1.391739

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

The purpose of this study was to investigate a numerical method for calculating impedances and standing wave patterns of flute structures. To this end, the physical dimensions of flute joints and tone holes were used to compute impedance and standing waves as a function of frequency for several different fingerings. Numerically computed resonance frequencies for head joint, middle and foot joints, and complete flute are compared to experimentally measured values. Computed pressure standing wave patterns for two fingerings of A6are compared to experimental values. Reasons for the observed discrepancies between the predicted and experimental frequencies are discussed.

ISSN:0001-4966    

DOI:10.1121/1.391740

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

A new method of measuring the acoustic parameters of porous materials is described. The method is based on the measurement of radiation impedance at the end of an open flanged pipe placed against a sample. Five samples of polystyrene foam of differing porosities have been used to assess the usefulness of the method. The acoustic characteristics of the samples were first determined using a conventional acoustic impedance tube with rigid end cap. Estimates of the acoustic parameters of the samples—sound speed and attenuation constant—were then obtained by applying various acoustic models to match the measured characteristics. Open tube measurements were then made on the samples and these impedance characteristics compared with those predicted by application of acoustic models. Moderately good agreement was obtained between measured and predicted impedance although the values of acoustic parameters derived deviated from those obtained from the closed tube measurements. The results confirm the potential of the method to be developed into an alternative method of measurement of acoustic absorptivity.

ISSN:0001-4966    

DOI:10.1121/1.391741

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

Reported herein is the derivation of an expression for sound pressure in the field of a point source of sound located on the surface of an otherwise rigid, immobile sphere. The derivation parallels those presented in several contemporary acoustics textbooks, but with the final equation given in terms of sound pressure: a useful quantity if one wishes to use such an equation to verify theory with actual sound‐pressure measurements. Unfortunately, the authors of these textbooks have not seen fit to present the results of their work in this form. Proof of the validity of the equation derived herein is given by first reducing the expression to its farfield and low‐frequency forms. These are then compared with similar forms of the equation which are, in fact, given in the referenced textbooks.

ISSN:0001-4966    

DOI:10.1121/1.391742

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

The absorption coefficient of ultrasound and shear viscosity in binary solutions of polyacrylamide with water were studied as a function of concentration and temperature. In addition, the absorption coefficient was measured as a function of frequency. The value of α/f2increased by twofold, at 3% concentration and 20 °C, from the water value while the shear viscosity increased by four orders of magnitude. The temperature dependence of α/f2for the polymer solutions is similar to that of pure water.

ISSN:0001-4966    

DOI:10.1121/1.391743

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

Large amplitude axisymmetric vibrations of uniform and tapered orthotropic annular plates with a rigid central mass are studied. A time‐mode solution of the von Kármán‐type‐governing equations is obtained using the Kantorovich averaging method. The orthogonal point collocation method is used for spatial discretization. The effect of various parameters is studied.

ISSN:0001-4966    

DOI:10.1121/1.391744

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

For rapidly adapting mechanoreceptor afferents, entrainment is defined as a response of one spike per stimulus cycle. For Pacinian corpuscles, the entrainment threshold and psychophysical detection threshold are similar. The psychophysical threshold, however, exhibits temporal summation, which proves that the psychophysical threshold and the physiological entrainment threshold cannot be identical.

ISSN:0001-4966    

DOI:10.1121/1.391745

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.392396

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP