Vehicle alarm systems and methods

A system for a motor vehicle, comprising:

• an alarm control unit;
• a sound emitting unit that emits a first sound and a second sound, wherein the first sound provides an audible warning to bystanders and wherein the second sound is a messaging sound for communicating information to at least one other vehicle;
• a sound detecting unit, the sound detecting unit configured to send a first triggering signal to the alarm control unit when the sound detecting unit detects sounds sufficiently similar to the second sound;
• a person detecting unit that receives information from a sensing device of the motor vehicle, and wherein the person detecting unit is configured to send a second triggering signal to the alarm control unit when the person detecting unit detects a person sufficiently close to the motor vehicle;
• and
• wherein when the alarm control unit receives the first triggering signal and the second triggering signal within a sufficiently close period of time, the alarm control unit signals the sound emitting unit to emit the first sound and the second sound.