| 摘要 |
<p>A dog whistle comprises a body formed in two parts (2,3) and provided with a mouthpiece (4) which communicates through an air passage (10) with a sound chamber (5) having a vent (6) provided with an air splitter (9), the air passage containing a ramp (8) which directs the airflow produced by blowing the whistle into the sound chamber and towards the air splitter which thereby produces a whistling sound. The chamber produces sound having a narrow frequency bandwidth lying in the range 400 to 800 Hertz, preferably about 400 Hertz. The diameter of the sound chamber is within about 10% of its length and the ramp is at an angle of less than 8 DEG , preferably 4 DEG 30', to the axis of the air passage. The angle of the surface of the air splitter is greater than 38 DEG preferably 55 DEG . <IMAGE></p> |
