What sound indicates activation of the lavatory smoke detector?

The sound that indicates activation of the lavatory smoke detector is a horn sound. This specific auditory alert is designed to be easily recognizable and to draw attention in an emergency situation. Its distinct nature ensures that crew members and passengers alike are immediately aware of a potential fire hazard in the lavatory, prompting prompt action in accordance with safety protocols. Additionally, the horn sound is crucial for indicating an emergency, as it breaks through background noise on the aircraft, ensuring it can be heard effectively. This understanding of emergency signals is vital for flight attendants, as it informs their response and safety measures in the event of a fire or smoke presence in the lavatory.