Abstract: A whistle for producing resonant frequencies comprising a body which includes a mouth piece having an inlet, and at least two sound chambers to which inlet air is blown from the inlet. The whistle further includes air passageways for communicating inlet air from the inlet to the sound box and sound chambers. The body further includes at least two exhaust ports in communication with the sound chambers for discharging air and sound. The two sound chambers are dimensioned to create peak principal frequencies which interactively produce a pulsating sound having a periodic pulse frequency of less than 100 hertz. The whistle preferably includes air intake ports for communicating additional port air into the sound box.

Abstract: A basketball sports whistle having an integral basketball possession indicator at the eye level of the referee enables the referee to accurately determine which team is entitled to possession of the basketball without diverting his eyes from the basketball court. The referee switches the indicator to record a change of ball possession. A friction or detent lock in the integrally constructed indicator prevents the ball possession indicator from being accidentally switched to a different position. The possession indicator element is a friction lock slider, or a pop-up indicator in a see-saw like element with friction or a detent at the axis of the see-saw. It can alternatively be or a single pop-up element that carries either H for home team basketball possession or V for visitor team basketball possession.