Abstract: 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°, preferably 4° 30′, to the axis of the air passage. The angle of the surface of the air splitter is greater than 38° preferably 55°.

Abstract: A comprising a body (1) provided at each end with a mouthpiece (3',6) having an air passage which communicates with a sound chamber (4,5), the chambers each being provided with a vent (V.sub.1, V.sub.2) in which is located an air splitter arranged so that air blown into the chamber through the associated mouthpiece is directed to the air splitter. The two vents (V.sub.1, V.sub.2) open at opposite sides of the body (1) so that the whistle can be blown from either end with the associated air vent exhausting in an upward direction by rotating the whistle about a generally horizontal axis when changing ends. One of the sound chambers (5) contains a pea and is provided with a protuberance (3c) arranged to project into the associated vent (V.sub.2) to prevent the pea becoming stuck in the vent. This chamber is of conical shape at one end.