How to blow into a Referee Whistle

We offer tips on how to blow into a Referee Whistle loudly and sharply.Here is the sounds of Sports Specific Whistles.www.molten.co.jp/sports/en/equ...
審判用ホイッスルの吹きかた。大きく、キレのある音の鳴らしたかのコツを紹介します。競技別吹き分けはこちら　www.molten.co.jp/sports/jp/equ...