Public address systems are a set of techniques whose primary purpose is to amplify and transmit sound, ensuring its intelligibility. Other equipment, such as professional sound systems or home HIFI systems, is generally intended to reproduce the original sound with maximum fidelity. In the case of public address systems, intelligibility prevails, and in many cases, for example, it is necessary to sacrifice bandwidth to avoid masking caused by ambient noise in a train station or airport lobby. Therefore, this articles will focus more on sound pressure, signal-to-noise ratio, coverage, and intelligibility than on fidelity, frequency response, or power.
Sound, whether defined as a mechanical vibration capable of producing an additive sensation (from a physical perspective) or as the auditory sensation produced by a mechanical vibration (from an acoustic perspective), is the subject of study in several disciplines. Physical acoustics, physiological and psychoacoustic acoustics, electroacoustics, architectural acoustics, musical acoustics, linguistics and phonetics…
To address the study of everything related to public address systems, it is necessary to review some basic knowledge of physical acoustics and electroacoustics, as a preliminary step to describing the methodology of acoustic studies and implementing public address systems projects.
Matter is made up of molecules, and molecules are made up of atoms. Each atom contains a nucleus, with neutrons and protons (+ charge), and electrons (- charge) orbiting it.
Electroacoustics encompasses the set of techniques that transform sound energy (music and speech) into electrical signals and restore them to their original state.
In both PA and any other audio application (home, studio, live, etc.), sound goes through three phases: capture and conversion into an electrical signal, signal processing and amplification, and conversion back into acoustic pressure through the speakers.
The equipment that makes up a sound system has a limited capacity to handle the audible frequency range (20–20,000 Hz). Frequency response is the behavior of the equipment at each frequency and is ultimately indicative of the fidelity of the electroacoustic system to the original signal.
Directionality or directivity is the microphone's sensitivity or speaker behavior depending on the angle at which the sound is incident or emitted. It is not the same for all frequencies and is represented by the polar diagram.
The microphone is the transducer that converts acoustic energy into electrical energy. Pressure variations act on a membrane, causing it to vibrate, ultimately producing electrical voltage.
The loudspeaker is the transducer that converts electrical energy into acoustic energy. The electrical energy causes the membrane to vibrate, which sets the surrounding air in motion, creating a pressure wave.
Ceiling speakers distribute sound directly above the listener, unobstructed, from relatively low ceilings over large areas. When installed with adequate spacing and sufficient power, the best-quality models provide even sound coverage and adequate frequency response for both speech and music.
We're here to help with whatever you need. Whether it's a one-off inquiry or more extensive advice, we'll be happy to help. Write to us without obligation and we'll respond as soon as possible. You can also contact us directly, either by phone or email. You'll find everything you need on our OFFICES and DISTRIBUTION pages.