For fans, the most heard on the court, in addition to the shouting of mountains and tsunami, must be the referee's whistle. Modern whistle is mostly made by plastic manufacturers.
People who have played the whistle should have the impression that there are many small balls in the whistle. The small balls will jump under the action of the air flow, the frequency of sound will also change, and the whistle will change.
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Last Update : Apr 24, 2020
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|Item Owner : chen|
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