摘要:

The fast field program (FFP) is a powerful tool for solving outdoor sound propagation problems in stratified atmospheres. It is shown here to be equally powerful for solving for the propagation of sound over curved surfaces of finite impedance. Results from scale model experiments are in excellent agreement with the FFP calculation in the deep shadow, penumbra, and bright zone behind the surface. The results are also compared with Berry and Daigle’s creeping wave series [J. Acoust. Soc. Am.83, 2047–2058 (1988)]. The FFP calculation and creeping wave series yield identical results in the deep shadow. In the penumbra and bright zone behind the curved surface the FFP is in slightly better agreement with the data than the creeping wave series, although the differences are typically 1 dB or less which is comparable to the experimental error. The improvement is due to the more accurate sound speed profile and coordinate mapping used rather than to any differences in the computational method.

ISSN:0001-4966    

DOI:10.1121/1.419739

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

Based on nitrogen sound speeds measured by Younglove and McCarty in 1980 [J. Chem. Thermodynam.12, 1121–1128 (1980)], a multicolumn coefficient fitting method is used to derive an empirical equation for the computation of sound speed at temperatures from 150 to 330 K and pressures from 0.028 75 to 1.506 85 MPa. The maximum deviation between the measured sound speeds and those computed with the empirical equation is less than 380 ppm.

ISSN:0001-4966    

DOI:10.1121/1.419710

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

In order to investigate whether nonlinear methods of signal analysis provide a measure of phonatory irregularities in neurogenic voice disorders, the present study computed the fractal dimension(D)both of the electroglottographic (EGG) and the acoustic signal of sustained vowel productions obtained from patients with Parkinson’s disease (PD) and cerebellar atrophy (CA). Compared with normal speakers, the female PD group as well as the male and female CA patients showed an increased dimension(D)of the EGG. The dimensional complexity of the acoustic signal largely depended on vowel type. Furthermore, the dimension of the acoustic signal was reduced in male PD patients as compared to the respective controls.

ISSN:0001-4966    

DOI:10.1121/1.419711

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

Vowel production data collected from 15 southern Californian English-speaking monolinguals is compared with data reported by Hillenbrand et al. [J. Acoust. Soc. Am.97, 3099–3111 (1995)] and Peterson and Barney [J. Acoust. Soc. Am.24, 175–184 (1952)]. Recordings were made of nine women and six men producing multiple repetitions of [i, ɪ, e, ɛ, æ, u, ʊ, o, ɑ, ʌ, ɹˌ]in three consonant contexts. The frequencies of the first three formants were measured by simultaneous comparison of wideband spectrograms, narrow-band FFT spectral slices, and LPC spectra taken at vowel center, or steady state where available. The Southern Californian data are seen to differ greatly from that described by Peterson and Barney (1952) and Hillenbrand et al. (1995).

ISSN:0001-4966    

DOI:10.1121/1.419712

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

摘要:

Additional partials can occur in the radiated tone of pianos at frequencies other than those predicted by classical string equations.

ISSN:0001-4966    

DOI:10.1121/1.419713

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.421016

出版商:Acoustical Society of America    

年代:1997

数据来源: AIP