| 摘要 |
A stethoscope includes a pair of binaurals and a chest piece with a rubber tube extending and connected therebetween. The chest piece has a body defining therein a cavity for movably receiving a frequency switching member which is movable between a first position and a second position. A retainer ring having a bore is fixed to the body to retain the frequency switching member within the cavity. The frequency switching member has a reduced end with a circumferential rib formed thereon extending through the bore of the retainer ring. The retainer ring has a circumferential rib which surrounds the bore and is in tight contact engagement with a membrane fixed to the body so as to define a first confined zone on the membrane which provides a first, low frequency vibration mode of the membrane. The frequency switching member is biased by a spring toward the first position where a projection formed on the frequency switching member partially extends out of the body through a through hole to be accessible by the user. The projection is depressible to have the frequency switching member move toward the second position, bringing the circumferential rib of the frequency switching member into contact engagement with the membrane so as to define a smaller confined zone on the membrane which provides a second, high frequency vibration mode of the membrane.
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