Emergency sound glossary: PAVA, VACIE, EVCS, EAS and the rest

Terms are grouped by subject. Where a standard defines a term, the standard is named.

Systems

PAVA: Public Address Voice Alarm. One system that does two jobs on the same amplifiers, loudspeakers and cables: everyday public address announcements and background music, and emergency voice alarm broadcasts, which take priority. “Public Address and Voice Alarm” with an “and” suggests two separate systems, which is not what PAVA means. Covered by BS 5839-8 for its fire function.

VAPA: Voice Alarm Public Address. The same idea as PAVA with the words reversed, used by some manufacturers and specifiers.

VAS: Voice Alarm System. A system that broadcasts speech messages, and an attention-drawing signal, when the fire alarm operates, to tell people what to do. The term BS 5839-8 uses.

VA: Voice Alarm. Short for voice alarm generally.

PA: Public Address. A sound system for non-emergency announcements, paging and music. On its own, a PA system has no fire function. Covered by BS 6259.

ESS: Emergency Sound System. A sound system used to broadcast information for the protection of life in an emergency. The broad term used in BS EN 50849 and BS 7827; a voice alarm is one kind.

EVAS: Emergency Voice Alarm System. Another name for a voice alarm system, more common in some specifications and outside the UK.

PAGA: Public Address General Alarm. The emergency sound system on ships, offshore platforms and similar installations, combining announcements with general alarm tones.

EVCS: Emergency Voice Communication System. A two-way speech system for emergencies: fire telephones used by firefighters and stewards, and intercoms in disabled refuges so that a person waiting for assisted evacuation can talk to a control point. Covered by BS 5839-9.

EAS: Evacuation Alert System. A system in a block of flats that lets the fire and rescue service sound alert devices in the flats on chosen floors, to change from “stay put” to evacuation. Not a fire alarm: it has no detectors or call points. Covered by BS 8629. See our guide to evacuation alert systems.

AFILS: Audio Frequency Induction Loop System. A hearing loop. It feeds sound as a magnetic field to hearing aids set to the hearing loop setting. Performance is measured to BS EN 60118-4.

FD&FA: Fire Detection and Fire Alarm system. The system of detectors, call points and sounders that detects a fire and raises the alarm. It triggers the voice alarm. Covered by BS 5839-1 in non-domestic premises.

Equipment

VACIE: Voice Alarm Control and Indicating Equipment. The control equipment of a voice alarm: it receives signals from the fire alarm, selects and plays messages, and monitors the system for faults. The product standard is BS EN 54-16.

CIE: Control and Indicating Equipment. The fire alarm control panel.

EACIE: Evacuation Alert Control and Indicating Equipment. The control panel of an evacuation alert system, in a locked cabinet for fire service use, with one switch per floor.

Loudspeaker circuit (loudspeaker line). The cable run from an amplifier that feeds a group of loudspeakers. Most voice alarms use 100 V line circuits, so that many loudspeakers can share one amplifier output.

End-of-line device. A component at the far end of a loudspeaker circuit that lets the control equipment detect a break or short in the cable.

Emergency microphone. A microphone that lets authorised staff or firefighters make live announcements with priority over recorded messages.

ANS: Ambient Noise Sensing. Automatic adjustment of announcement volume to suit background noise. BS 5839-8 recommends it fails safe, so that a fault does not leave announcements too quiet.

Standby battery. The batteries that keep the system running when the mains fails. For a voice alarm, BS 5839-8 recommends 24 hours of standby followed by 30 minutes of evacuation broadcast; for an evacuation alert system, BS 8629 recommends 72 hours followed by 30 minutes.

Messages and zones

Alert message. A message telling people that an incident is being investigated and to be ready to leave.

Evacuate message. A message telling people to leave now by the nearest exit.

Attention-drawing signal. The tone played before each message to make people listen.

Cause-and-effect. The agreed schedule of which fire alarm signals trigger which messages in which zones. The weekly voice alarm test checks part of it.

Loudspeaker zone. An area that receives the same message at the same time. Voice alarm zones should normally line up with fire detection zones.

Phased evacuation. Evacuating a building in stages, usually the fire floor and the floor above first, with alert messages elsewhere. Common in tall buildings and one of the main reasons a voice alarm is chosen over bells.

Invacuation (lockdown). Moving people inside, or keeping them inside, away from a threat outside. A non-fire use of emergency sound, covered by BS EN 50849.

Sound and intelligibility

dB(A), dBA. Sound level in decibels, A-weighted to match how the ear hears. BS 5839-8 recommends at least 60 dBA for voice alarm signals in general areas.

Intelligibility. Whether a listener can understand the words, which is different from whether the message is loud enough.

STI: Speech Transmission Index. A measured rating of intelligibility from 0 (unintelligible) to 1 (perfect), defined in BS EN IEC 60268-16. For a voice alarm, BS 5839-8 recommends an average of at least 0.50 across the measurement points.

STIPA: STI for Public Address systems. The practical method of measuring STI with a special test signal played through the system and a hand-held meter.

Reverberation time (RT). How long sound takes to die away in a space. Long reverberation, as in atria, stairwells and sports halls, blurs speech.

People and paperwork

Premises management. The people responsible for running the building day to day. Voice alarm and evacuation alert standards give them the weekly or monthly checks and the logbook.

Responsible person. In England and Wales, the person with legal duties for fire safety in a building under the Regulatory Reform (Fire Safety) Order 2005, usually the employer or the person in control of the premises.

Competent person. Someone with the training and experience to do a task properly. The standards recommend that design, commissioning and servicing are done by competent people.

Logbook. The on-site record of tests, faults, disablements and maintenance visits. Both BS 5839-8 and BS 8629 recommend one, and it should be available to enforcing authorities.

Variation. An agreed and recorded departure from a recommendation in a code of practice. A variation is not a fault, as long as it was agreed and written down.

Modification certificate. The certificate issued after significant changes to a system, such as adding loudspeakers, amplifiers or zones, or changing the cause-and-effect.

As-fitted drawings. Drawings showing the system as actually installed, including cable routes. Produced by the installer and kept by premises management.