Fire Alarm System Intelligibility

Transcription

1 Fire Alarm System Intelligibility Design Strategies For Compliance The Degree To Which The Occupants Understand The Spoken Language Fire Alarm System Intelligibility STORED MESSAGES 1

2 QUESTIONS REGARDING LIFE SAFETY SYSTEM COMPLIANCE WHEN THIS HAPPENS 1 Determining Intelligibility In Retrofit Applications 2 Analyzing The Audibility SPL Data and the Intelligibility CIS Data 2

3 3 Design for Audibility & Intelligibility Step 4 The Installation Step 4 The Installation 4 Speaker Installation for Intelligible Voice Step 5 Intelligibility Commissioning Step 5 Intelligibility Commissioning 5 Did We Get It Right Tweaking the Solution 3

4 THE MESSAGE KNOWLEDGE IS POWER LEVERAGE NEW TECHNOLOGY TO PROVIDE INTELLIGABLE EMERGENCY VOICE PAGING To further protect society from the ravages of fire REVIEW-ANALYIZE-DESIGN-INSTALL-COMMISSION 1 Determining Intelligibility In Retrofit Applications 4

5 The First Indicator Hey it works? Can he hear intelligible voice Documents 5

6 OBJECTIVES Emergency Voice/Alarm Communications System Emergency voice/alarm communications systems are used in applications where it is necessary to communicate more detailed information to occupants of a building than the simple evacuation signal provided by horns or bells. For example, in a high-rise building, evacuation of all of the occupants at one time could create an unsafe situation in which the routes to evacuation could be blocked by the sheer number of people trying to exit at once. 12 Voice Communication System Initial Review Of Existing System STORED MESSAGES Determine Audibility A measure of loudness of a sound. When used with respect to fire alarm systems, audibility is regarded as the evacuation signal level above background noise 6

7 Audibility Requirements SIGNAL LEVELS SHALL BE A MINIMUM OF 15 dba ABOVE AMBIENT BUT NOT LESS THAN 65 dba (Ref: National Building Code) Minimum Audibility Level DECIBELS Library Audibility Requirements SIGNAL LEVELS SHALL BE A MAXIMUM OF 100 dba IN A NORMALLY OCCUPIED AREA (Ref: Ontario Building Code) DECIBELS TOO LOUD Busy Factory Noisy Crowd Library Audibility Inverse Square Law 90 db 78 db 84 db 3 m 6 m SOUND DEVICE 72 db 12 m 24 m DISTANCE X 2 = -6dB DISTANCE = +6 db 2 7

8 GIS Audibility Review Mapping on the Drawing Ambient and Alarm SPL Ambient SPL equal to or over 60 dba Evacuation SPL Readings Areas requiring more analysis Geospatial Information System Mapping the SPL Common Intelligibility Scale The capability of being understood or comprehended. 8

9 Geospatial Mapping of CIS Maintaining occupant fire safety in and around buildings Intelligibility Testing 2 Analyzing The Audibility SPL Data and the Intelligibility CIS DATA 9

10 Analyzing Audibility The Analysis Evacuation SPL Reading THE OCCUPANTS CANNOT HEAR THE EVACUATION ALARM SIGNALS Ambient SPL Reading Issue: Evacuation Alarm Signal is 33dBA lower than the ambient noise level Ambient SPL equal to or over 60 dba Evacuation SPL Readings Areas requiring more analysis dba Analyzing Acoustics Room Acoustics Reverberation is produced when sound is reflected off walls and other surfaces Reverberation contains the original sound jumbled into something not distinctly identifiable Analyzing Acoustics Room Acoustics Reverberation should not be confused with echoes Echo is a delayed but distinct reproduction of an original sound Echoes are generally not a problem, but reverberation can have a major impact on ambient noise and intelligibility 10

11 Data Mining For Intelligibility Analyzing Intelligibility Metrics.63 CIS versus Signal to Noise Ratio.63 11

12 Equal Loudness Curves The Minimum Audible Field Curve SPL IN dba Frequency in Hz Analyzing Intelligibility Metrics Analysis Defined Language CIS RASTI STI %ALcons COMMON INTELLIGIBILITY SCALE Rapid Acoustic Speech Transmission Index Speech Transmission Index Articulation Loss Of Consonants Speech Range 125 Hz to 8KHz Maintaining occupant fire safety in and around buildings The creation of phonemes, or the sounds that make up words is created by amplitude modulation of voice frequencies 12

13 Speech Pattern Modulations Amplitude modulations of speech patterns are seen as the peaks and valleys of the waveform. These modulations range from 0.63 Hz to 12.5 Hz. 3 Design for Audibility & Intelligibility Intelligible Design Starts with the Building Code 13

14 2005 NBC (b) Voice Communication Systems 1(b) loudspeakers operated from the central alarm and control facility that are designed and located so as to be audible and the messages intelligible in all parts of the building, except that this requirement does not apply to elevator cars. Clause (b) prescribes that the emergency voice page messages be both audible (we can hear it) and intelligible, (we can understand it) in all parts of the building; (except inside the elevator). Intelligible Speech and the Designer How do we design emergency voice systems so that they provide intelligible speech? Do we need more loudspeakers at lower output or do we need fewer loudspeakers with higher output? Ceiling Mount Speaker Layout Patterns 2 x Edge-to-Edge Does not provide intelligible voice but is acceptable for tone only Signalling 14

15 Ceiling Mount Speaker Layout Patterns 1.4 x Edge-to-Edge Good for rooms with low background noise and little reverberation Ceiling Mount Speaker Layout Patterns Edge-to-Edge Preferred layout for typical applications Ceiling Mount Speaker Layout Patterns Minimum Overlap Preferred layout for high reverberation and/or high ceilings 15

16 Ceiling Mount Speaker Layout Patterns Full Overlap For the worst areas, full overlap provides excellent intelligibility however acoustic modeling is recommended to determine speaker interaction SPL Variation by Layout Pattern Sound Pressure Level by Layout Pattern SPEAKER LAYOUT PATTERN 2X Edge to Edge 1.4X Edge to Edge Edge to Edge Minimum Overlap Full Overlap INCREASE IN SPL OVER A SINGLE SPEAKER 0.2 db 0.4 db 0.7 db 2.0 db 5.2 db VARIATION IN COVERAGE db db db - 2.0dB - 1.4dB VARIATION IN COVERAGE db Wall Mount Speaker Coverage 16

17 Wall Mount Speaker Coverage Coverage patterns for wall mount speakers are similar for distributed overhead systems Wall Mount Speaker Coverage Edge to Edge Minimum Overlap Full Overlap Intelligibility Modeling 17

18 Intelligibility Modeling Automation SPL Distribution Modeling Step 4 The Installation Step 4 The Installation 4 Speaker Installation for Intelligible Voice 18

19 Class A & Class B Wiring Step 4 The Installation e e e Voice Paging Zone Delineation Step 4 The Installation Step 5 Intelligibility Commissioning Step 5 Intelligibility Commissioning 5 Did We Get It Right Tweaking the Solution 19

20 C6.3 Signaling Device Sound Level Measurement Step 5 Intelligibility Commissioning (Reference: CAN/ULC-S Clause C) Building Name: ZONE LOCATION AMBIENT ALARM SIGNAL REMARKS Floor 1 East Wing 65 dba 83 dba +18 db Floor 2 North Wing 73 dba 40 dba -33 db FLOOR 1 East Wing EOL Step 5 Intelligibility Commissioning Fire Alarm System Intelligibility Design Strategies For Compliance 20