Today Federal Signal 's Q2B siren is still in wide use The majority of users of the Q Siren are fire departments , although some ambulances and heavy rescue squads have employed the Q - siren because of its pitch recognizable sound .
Today Federal Signals Q2B siren is still in wide use The majority of of users of the Q Siren are fire departments . 
 Although the majority of users are fire departments some ambulances and heavy rescue squads have employed the Q siren because of its pitch recognizable sound .