A flow controlled sound generation system is disclosed that includes one or more fluid pumps to control air flow through a sound channel. The air flow is modulated through one or more valves to produce audible frequency pressure waves.

A flow controlled sound generation system is disclosed that includes one or more fluid pumps to control air flow through a sound channel. The air flow is modulated through one or more valves to produce audible frequency pressure waves.

Examples provide a siren device having a plurality of lockable functions, such as amplifier strength and siren tone functions. At production, one or more of the available functions are placed in a locked state in which the locked function is inoperable. One or more of the functions may be initially unlocked at manufacture or purchase. The user can obtain an unlock code to unlock one or more of the functions, if desired, after purchase. Thus, if a user wants to increase the amplifier strength from one-hundred watts to two-hundred watts, the user can obtain one or more unlock codes to unlock that selected function for a licensed time-period. When unlocked, the selected function operates normally. A data storage device on the multifunction siren device stores an assigned UID, a set of available lockable functions, and a lock status of each function in the set of available functions.

A flow controlled sound generation system is disclosed that includes one or more fluid pumps to control air flow through a sound channel. The air flow is modulated through one or more valves to produce audible frequency pressure waves.

A flow controlled sound generation system is disclosed that includes one or more fluid pumps to control air flow through a sound channel. The air flow is modulated through one or more valves to produce audible frequency pressure waves.

A flow controlled sound generation system is disclosed that includes one or more fluid pumps to control air flow through a sound channel. The air flow is modulated through one or more valves to produce audible frequency pressure waves.

A flow controlled sound generation system is disclosed that includes one or more fluid pumps to control air flow through a sound channel. The air flow is modulated through one or more valves to produce audible frequency pressure waves.

A vehicle includes an alarm system for producing an alarm signal in response to reversing of the vehicle. The system includes a device including a memory for storing a plurality of selectable discrete digital data signals, each of which when applied to a sounder of the system operates the sounder to produce a sound pattern which is different to the sound patterns produced by the other selectable discrete digital data signals when applied to the sounder. A microprocessor controls the operation of the system. A pseudo-random number generator generates random numbers so that the discrete digital data signals stored in the memory can be randomly selected each time reverse gear is selected in the vehicle. A sensor mounted on the gearbox of the vehicle produces an activation signal on a reverse gear being selected which is read by the microprocessor.

A flow controlled sound generation system is disclosed that includes one or more fluid pumps to control air flow through a sound channel. The air flow is modulated through one or more valves to produce audible frequency pressure waves.

A flow controlled sound generation system is disclosed that includes one or more fluid pumps to control air flow through a sound channel. The air flow is modulated through one or more valves to produce audible frequency pressure waves.