Buzzer, sounder, siren, horn — what the terms actually mean
Industrial catalogues use these terms fairly consistently by loudness and application, even though they're all audible alarm devices. Buzzers are the quietest — typically 75–85dB — and suit local panel or equipment status alerts where someone is standing nearby. Electronic sounders sit in the middle, often 80–105dB, and frequently offer several selectable tones so one device can signal more than one condition. Sirens and horns are the loudest category, 105dB and up, used for site-wide or emergency alerts that need to carry over a noisy factory floor or outdoors.
Sizing the decibel rating to the environment
The rating that matters is decibels at 1 metre, and the goal is for the alarm to read clearly above ambient background noise at the point people actually need to hear it — most workplace alarm guidance points to the alarm being comfortably audible over background noise at the listener's position, not just louder in absolute terms. On a loud production floor with 85dB+ ambient noise, that generally rules out a standard panel buzzer and points to a 100dB+ sounder or horn. Always check the specific safety standard or site requirement that applies to your facility rather than relying on a rule of thumb alone.
Tones, IP rating and supply — the rest of the spec sheet
A single-tone sounder is the simplest and usually cheapest option for one dedicated alarm condition. A multi-tone unit — some ranges offer dozens of selectable tones — lets a single sounder cover several distinct states (warning, fault, evacuate) without installing separate devices. Match the IP rating to the mounting location: IP20 is typical for indoor panel-mount units, IP65 for general outdoor or wet-area use, and IP66/IP69K for washdown environments. And confirm current type and voltage against your control circuit — DC units (commonly 12–24V) and AC units (commonly 115V/230V) aren't interchangeable.