摘要:

Using a go/no go response paradigm, a tucuxi (Sotalia fluviatilis guianensis) was trained to respond to pure-tone signals for an underwater hearing test. Auditory thresholds were obtained from 4 to 135 kHz. The audiogram curve shows that thisSotaliahad an upper limit of hearing at 135 kHz; from 125 to 135 kHz sensitivity decreased by 475 dB/oct. This coincides with results from electrophysiological threshold measurements. The range of best hearing (defined as 10 dB from maximum sensitivity) was between 64 and 105 kHz. This range appears to be narrower and more restricted to higher frequencies inSotalia fluviatilis guianensisthan in other odontocete species that had been tested before. Peak frequencies of echolocation pulses reported from free-rangingSotaliacorrespond with the range of most sensitive hearing of this test subject.

ISSN:0001-4966    

DOI:10.1121/1.421228

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

摘要:

This Letter considers scattered sound from transiently oscillating gas bubbles in liquids. The full transient problem including the finite duration of the excitation is analyzed. As a result, the wave front of the radiated sound pulse involving information about the excitation is also studied. The model presented is used to simulate sound pulses from sea-surface bubbles which have been generated by, for example, spilling breakers, capillary-gravity waves, and rain drops. Although very simple in relation to the actual physical process of excitation, this model enables us to predict some of the essential properties of scattered pulses observed experimentally. It is suggested that the time scale of duration of the initial driving that enters into the present analysis might be of some use in a further physical understanding of bubble generation and excitation.

ISSN:0001-4966    

DOI:10.1121/1.421251

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

摘要:

Acoustic scattering from two junctions in a rectangular waveguide is studied. Fourier transform and mode matching are used to represent the scattered wave and the simultaneous equations for the modal coefficients are formulated. The residue calculus is utilized to obtain a solution to the simultaneous equations in fast-converging series. Numerical evaluation shows the behaviors of transmission and reflection in terms of the junction geometry and operating frequency.

ISSN:0001-4966    

DOI:10.1121/1.421252

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

摘要:

Most objective indices for speech intelligibility are essentially based on studies of Western languages and not tonal languages like Chinese. Consequently, if speech intelligibility in an enclosure is satisfactory for English, it is not necessarily satisfactory for Chinese, orvice versa. In this research, the differences in intelligibility between English and Mandarin (a spoken language of Chinese) have been investigated by carrying out a series of articulation tests in a long corridor and a regularly shaped (i.e., quasi-cubic) seminar room, using loudspeaker sources. The results suggest that in terms of speech intelligibility, Mandarin is slightly better than English under reverberant conditions, and English is considerably better than Mandarin under noisy conditions.

ISSN:0001-4966    

DOI:10.1121/1.421253

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

摘要:

Using an electronic system for pulsed TV holography with a double-pulsed ruby laser, transient wave propagation during intervals from 30 to 480 μs after impact is recorded. The first observable bending waves, having wavelengths of about 5 mm, propagate at about 1700 m/s, and reach the edge of the cymbal in about 60 μs. These are quickly followed by waves of longer wavelength which scatter at the outer edge of the cymbal and also the central dome and result in standing waves. A phase unwrapping procedure is used to obtain a three-dimensional map of the wave field. Holographic film recordings similarly show scattering of transient bending waves at the central dome.

ISSN:0001-4966    

DOI:10.1121/1.421254

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

摘要:

ISSN:0001-4966    

DOI:10.1121/1.421382

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.421171

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.421168

出版商:Acoustical Society of America    

年代:1998

数据来源: AIP