摘要:

When pulse‐echo methods are used to measure sound velocity and attenuation, a lack of parallelism between the sound generator and the reflector causes an interference envelope to be superimposed upon the echo train if the attenuation is low. This envelope is calculated for nonzero attenuation and several transducer‐reflector configurations: (a) a tilted reflector with pistonlike sound generation, (b) a tilted reflector with an initial nonuniform amplitude distribution on the transducer, and (c) a spherically curved reflector and a nonzero beam deviation. In each case expressions are obtained for the echo envelope, for the positions of the maxima and minima and for corrections to measurements of sound velocity and attenuation. The results are applied to data taken with samples of solid helium.

ISSN:0001-4966    

DOI:10.1121/1.381777

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

摘要:

The effects of steady‐state acoustic stimulation on resistance to fatigue as shown by reduction of swimming time was studied on three sublines of mice, one of which is genetically deaf. High frequencies (500–10 000 Hz) reduce swimming time from 25% to 50% in mice with normal hearing at a 60–80‐dB threshold, but have no effect on deaf mice. Low frequencies and infrasounds (6–50 Hz) reduce swimming time in all mice similarly, even deaf animals, but the threshold is higher (160–115 dB). The use of genetically deaf animals therefore permits elimination of the auditory component; differentiation of the effects of air‐born sound from those of mechanical vibrations are thus possible.

ISSN:0001-4966    

DOI:10.1121/1.381778

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP

ISSN:0001-4966    

DOI:10.1121/1.381934

出版商:Acoustical Society of America    

年代:1978

数据来源: AIP