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.