#sound system
- Alarm — A predefined acoustic, visual, or electronic signal emitted by a specialized device to warn of an imminent danger, an unauthorized intrusion, or a major emergency; by extension, a state of alert, profound anxiety, fear, or collective agitation caused among the population by the emergence of a threat. This structural mechanism includes both automated warning systems (fire, burglar alarms) and the psychological or operational reaction of immediate mobilization of intervention resources.
- Stereo receiver — A complex high-fidelity electronic apparatus that structurally combines a radio receiver (tuner) and an audio power amplifier within a single chassis. This device allows selecting, receiving, and decoding radio stations broadcast over ultra-short or medium waves, while simultaneously ensuring signal amplification and its efficient distribution to a modular speaker system.