Designing for Intelligibility & Energy Efficiency Eaton, All Rights Reserved.

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Arnold Flynn
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1 Designing for Intelligibility & Energy Efficiency

3 Audibility & Intelligibility NOT the same! Think of the sayings: I hear you LOUD & CLEAR I have you 5 by 5 Military/radio jargon for subjective loudness & clarity measurements. 5x1 is loud, but not clear, 1x5 is not loud but crystal clear 3

Audibility Defined Measured in decibels (db, dba) The state or quality of being perceptible by the human ear Normal Calculations for Fire Alarm professionals fairly

4 Audibility Defined Measured in decibels (db, dba) The state or quality of being perceptible by the human ear Normal Calculations for Fire Alarm professionals fairly straight-forward 15 dba over ambient Double the distance from the source & lose 6 db examples: 100 db at 10, 94 db at 20, 88 db at 40 Measurable with Type II Sound Level Meter Goldline, etc. 4

Intelligibility Defined is a measureable aspect of electronic voice transmission systems that indicates the degree that human listeners will be able to understand the voice messages transmitted

5 Intelligibility Defined is a measureable aspect of electronic voice transmission systems that indicates the degree that human listeners will be able to understand the voice messages transmitted through them. Fire Protection Research Foundation (FPRF) Measurement is usually expressed as a percentage of a message that is understood correctly A variety of test methods are available to measure intelligibility 5

Latest Intelligibility Standard Overview Mandatory for DoD MNS UFC New UFC requires exterior testing Computer designs EASE Evac NFPA 72 2013 Clarified intelligibility testing requirements Up to

6 Latest Intelligibility Standard Overview Mandatory for DoD MNS UFC New UFC requires exterior testing Computer designs EASE Evac NFPA Clarified intelligibility testing requirements Up to governing laws, AHJ, or codes to specify where voice signaling must be intelligible In absence of codes, the system designer must designate which ADS will have intelligible voice Where required by AHJ or codes, ADS/intelligibility plans must be submitted for approval UNIFIED FACILITIES CRITERIA (UFC) EASE Evac -Speech Transmission Index (STI) 6

7 Introduction to Intelligibility Whole new animal Requires knowledge of sound Design usually done with computer modeling Renkus-Heinz Bose Others Very dependent on area acoustics 7

Room Finish Affects Intelligibility Changing room finish from carpet to ceramic tile will usually make intelligibility WORSE, but may make audibility better.

8 Room Finish Affects Intelligibility Changing room finish from carpet to ceramic tile will usually make intelligibility WORSE, but may make audibility better. Changing room finish from tile to shag carpeting will usually make intelligibility BETTER, but will make audibility worse. Have to keep up with room finish changes on projects. 8

Speech Intelligibility Test Methods Subject-based ANSI S3.2 Phonetically Balanced Word Scores (PB) = (256 words or 1000 words) Modified Rhyme Test (MRT) Instrument-based ANSI S3.

9 Speech Intelligibility Test Methods Subject-based ANSI S3.2 Phonetically Balanced Word Scores (PB) = (256 words or 1000 words) Modified Rhyme Test (MRT) Instrument-based ANSI S3.5 Articulation Index (AI), now referred to as Speech Intelligibility Index (SII) Calculated from acoustical measurements of speech and noise Speech Transmission Index (STI) Predicts how the characteristics of the transmission channel affect speech intelligibility Speech Transmission Index for Public Address (STIPA) Modified method of STI Common Intelligibility Scale (CIS) Developed to show the relationship between the different test methods 9

10 Intelligibility Measurement Standards Designing for intelligibility takes practice Design for COMPLETED & OCCUPIED spaces unless specifically directed to do otherwise Measured in Common Intelligibility Scale (CIS) NPFA or higher usually passing Trend is to measure in Sound Transmission Index Public Address (STIPA) NFPA or higher usually passing DoD facilities are required to test voice intelligibility using CIS or STI Army & Air Force Minimum CIS 0.8 (0.75 can be rounded to 0.8) Navy & Marines Minimum CIS 0.7 MAKE SURE TO KNOW WHAT YOU ARE MEASURING! 0 STI Bad Poor Fair Good Excellent 0 CIS

11 Design General Rules Of Thumb LOTS of speakers at lower wattage taps Can be as high as 8 times the speakers used to achieve audibility alone Example - Airports Increasing the wattage of speaker often distorts the message Ideal point-source (speaker to listener) is 20 or less Make sure all speakers in aural range are IN PHASE Ceiling height is speaker spacing Refer to NFPA documents for guidance Important: Speaker placement, type of speaker, spacing and power 11

Frequency Response Range Humans hear by frequency response Most energy of normal speech is 500 Hz to 4 KHz Fire Alarm/MNS systems generally produce frequency responses of 400 Hz to 4 KHz Commercial

12 Frequency Response Range Humans hear by frequency response Most energy of normal speech is 500 Hz to 4 KHz Fire Alarm/MNS systems generally produce frequency responses of 400 Hz to 4 KHz Commercial sound systems generally produce frequency responses of 125 Hz to 12.5 KHz. Pro sound system generally produce frequency responses of 20 Hz to 20 KHz. Humans can hear from around 50Hz up to 22kHz and most past 50 cannot hear above 10 KHz 12

Frequency Response The wider the frequency response of a speaker, the better it reproduces the frequencies in the

of the information in what was originally said.

critical elements of speech, the consonants, lie above it 3 khz.

13 Frequency Response The wider the frequency response of a speaker, the better it reproduces the frequencies in the original signal If the loudspeaker reproducing speech can t handle certain frequencies in that speech, you ll lose some of the information in what was originally said. Wider frequency response means that the speaker makes the speech easier to understand to whomever is listening The most critical elements of speech, the consonants, lie above it 3 khz. Frequency that distinguishes the "s" in "sailing" from the "f" in "failing" occurs between 4 khz and 14 khz. Emergency Reduce the chances of Stair B being misinterpreted as Stair D, Stair C or Stair E Wider frequency response = Higher intelligibility 13

14 STIPA & MNEC/FA STIPA uses frequencies of 125 Hz to 8 KHz (Typical MNS/FA systems produce 400 Hz to 4KHz) Best case testing of many MNS/FA systems with no appreciable wiring and near perfect acoustics in the aural field is 0.75 STIPA (0.5 passing) or 0.85 CIS (0.7 passing). This means that acoustics and speaker performance must be evaluated carefully before installing a system. 14

Cautions For Intelligible Design Not all areas can achieve intelligibility Think of historic building, polished marble floors & walls, hard plaster ceiling, no carpeting, no baffling Machinery &

15 Cautions For Intelligible Design Not all areas can achieve intelligibility Think of historic building, polished marble floors & walls, hard plaster ceiling, no carpeting, no baffling Machinery & high-ambient SPL areas may not be able to achieve good intelligibility Reasonable approach for such areas may be rally points where intelligibility can be obtained (people hear audible signal & have to go to a place to comprehend an intelligible signal) 15

Wide-Area MNS in the middle of winter when trees are bare without considering trees in full

16 Designing for Outdoors Additional parameters Wind Temperature Humidity Changing of the environment due to seasons, age, and time Vegetation growth affects sound Designing a Wide-Area MNS in the middle of winter when trees are bare without considering trees in full bloom can greatly affect the intelligibility of the system Same principals for indoors apply to outdoor areas 16

17 Intelligibility Testing Before testing, make sure: Audibility is achieved Audio system is balanced Amps are calibrated Control room is QUIET Radios, talking, door slams, etc. will mess up testing Construction is done 17

19 History of Intelligibility NFPA Edition 1 st edition having mandatory requirements for notification appliances Textual audible appliances (speakers) required to reproduce normal voice frequencies 1999 Edition Included definition of Voice Intelligibility Audible voice information that is distinguishable and understandable Emergency systems have messages with voice intelligibility - most information was placed in the annex. There was a proposal to add a requirement to the body of the code that systems provide.7 CIS. This was rejected by membership References to IEC standards for quantitative measurement approaches 2002 Edition Added Guidance to designers 2007 Edition Intelligibility referenced in more locations Incorporated Annex E on MNS, which generated renewed focus on intelligibility 19

History of Intelligibility NFPA 72 Task Group formed at end of 2007 Code cycle to develop an approach for mandating quantifiable measurement of voice intelligibility Task recommended adoption of ISO

20 History of Intelligibility NFPA 72 Task Group formed at end of 2007 Code cycle to develop an approach for mandating quantifiable measurement of voice intelligibility Task recommended adoption of ISO , Design, installation, commissioning and service of sound systems for emergency purposes FPRF project formed after ROP New Definition for Intelligible New Definition for Intelligibility New Definition for Acoustically Distinguishable Space Expanded Annex to provide guidance on design for intelligibility and methods for quantitative measurement 20

21 For Intelligible Design Will need to know: All room dimensions Room use Room occupancy Room finishes & treatments Speaker polar plots Intelligibility of Fire Alarm and Emergency Communication Systems Fire Protection Research Foundation November

22 Intelligibility & ADS Defined Chapter 3 NFPA & 2013: New/Revised Definitions Intelligibility The quality or condition of being intelligible Intelligible Capable of being understood; comprehensible; clear Voice communications used in emergency communication systems (ECS) Change from 2007 Audible voice information that is distinguishable and understandable Acoustically Distinguishable Space (ADS) Emergency Communication System notification zone, subdivision or physically defined space Distinguished from other spaces because of different acoustical, environmental or use characteristics (reverberation time, ambient sound pressure) All parts of a building intended to have occupant notification are subdivided into ADSs 22

23 Documentation - Chapter 7 NEW to NFPA Minimum protocol for documentation; May or may not be required by AHJ Some information was dispersed among a number of chapters. NEW - Written narrative must be included as part of the submittal drawings Forms completely revised so they are easier to use with a basic form for straight forward systems and supplemental forms for more complex systems Directives to provide Ambient noise and audible design sound pressure levels Extensive emergency communication systems design document requirements 1. Emergency Communication System Supplementary Record of Completion 2. Mass Notification System Supplementary Record of Inspection and Testing Includes Sound pressure levels and System intelligibility CSI or STI with locations, values and weather conditions. 23

24 Voice Intelligibility & ADS - Chapter 18 NFPA & 2013: New/Revised Definitions Voice Intelligibility within the ADS Where voice intelligibility is required, voice communications systems shall reproduce pre-recorded, synthesized or live messages with voice intelligibility ADS determined by system designer during planning and design of all ECS Each ADS shall be identified as requiring or not requiring voice intelligibility Update in 2013 Requirement to document which locations will have audible notification & which areas will not Statement that coverage area for audible occupant notification shall be as required by other governing laws, codes, or standards such as local building or fire codes. Requirement to document sound pressure levels of the notification appliances for the various coverage areas for use during acceptance testing. If required by AHJ, documentation may need to be submitted for review and approval. Intelligibility shall not be required to be determined through quantitative measurements Quantitative measurements as described in Annex D shall be permitted but not required 24

25 Steps to Identifying ADS Each ADS shall be identified as requiring or not requiring voice intelligibility 25

Indoor Voice NOT Required Moved from Chapter 24 to Chapter 18 Unless specifically required by other governing laws, codes or standards, or by other parts of this Code, intelligibility shall not be

26 Indoor Voice NOT Required Moved from Chapter 24 to Chapter 18 Unless specifically required by other governing laws, codes or standards, or by other parts of this Code, intelligibility shall not be required in all ADS. For example: Private bathrooms, showers rooms, saunas etc. Mechanical/electrical/elevator equipment rooms Elevator cars Individual offices Kitchens Storage rooms Closets Rooms/areas where intelligibility cannot reasonably be predicted 26

27 ECS/MNS Chapter 24 NFPA Numerous changes to correct minor errors and references Improvements on ECS operations, intelligibility and documentation Sound and communications issues continue to evolve NEW Microphone Use Users shall be provided with posted instructions for microphone use Characteristics of the system microphone are important ergonomic factors that affect Voice Intelligibility Message Templates Introduced into the Code, which requires that messages be developed for each scenario in the emergency response plan For all evacuation messages, a tone in accordance with Chapter 18 must be used with 2 cycles before and after the message as a minimum All test messages must clearly state: This is a Test Message. 27

28 Voice Evacuation in Sleeping Rooms Chapters && NFPA Low Frequency Sounders (18) Effective Jan 1, 2014, audible appliances provided for sleeping areas to awaken occupants shall produce a low frequency alarm signal that complies with Alarm signal shall be a square wave or provide equivalent awakening ability Wave shall have a fundamental frequency of 520 Hz + 10 percent Low frequency audible signal required in areas intended for sleeping and in areas that might reasonably be used for sleeping i.e. Apartment bedroom and the living room area of an apartment as it might have sleeping occupants Hotel guest rooms Voice Evacuation (24) In occupancies were sleeping accommodations are provided and the voice message is intended to communicate information to those who could be asleep, a low-frequency tone that complies with shall be used for the 2 cycles before and after the message 28

29 Speech Intelligibility Annex D NFPA & 2013 Guidance on planning, design and testing of voice communication systems Acoustic performance parameters of chosen loudspeakers and placement are key to determining how many appliances are necessary for adequate intelligibility Numerical count of appliances for a given design and protected space can NOT by itself be used to determine the adequacy of the design Acoustical problems of certain placement constraints can be overcome through careful selection of loudspeakers with requisite performance characteristics, rather than increasing their number Environmental Factors Ambient noise level in ADS Physical room characteristics Frequency and level of ambient sound pressure level might require components that have a wider frequency range Fire alarm speakers designed in accordance with UL 1480 are only tested for and required to produce frequencies of 400 to 4000 Hz (average range for human ears) Speech includes a wider range of frequencies STI and STIPA range from 125 Hz to 8000 Hz Under certain acoustic conditions, systems that do not produce the highs and lows, can produce speech intelligibility that is less than desired Wider frequency response sounds better and is more intelligible to listeners 29

30 Voice Intelligibility for ECS Supplement 2 NFPA & 2013 A well-spoken intelligent message in the listener s native language can be misunderstood if it is: 1. NOT audible to the listener 2. Distorted by the delivery system 3. Distorted by the acoustic environment Factors affecting intelligibility Signal to noise ratio Audibility is relative to the background noise Frequency response Harmonic Distortion Reduction of clarity by distortion can be caused by: 1. Amplitude distortion caused by electronics/hardware 2. Frequency distortion caused by electronics/hardware or the acoustic environment 3. Time domain distortion due to reflection and reverberation in the acoustic environment Noise, Frequency Response, Distortion & Physical Characteristics Affect Intelligibility 30

31 Voice Signal Path Voice Signal Path Talker Microphone Mixer Amplifier Speaker Rooms/Space Listener + Language Speed Articulation Bandwidth Distortion Noise, Reverberation Language Hearing Assumed Normal Intelligibility Measures Assumed Normal 31

33 Message Content & Delivery NIST Technical Note 1779 Feb NIST workshop identified a need for further research on messaging and communications strategies Guidance on how to create and disseminate emergency information (audible and visual) Understanding of human response to emergency communications Ways to improve response via more effective messages, message formatting and message dissemination Guidance on both alert signals and warning messages Latest Technical Note Draft Nov Message templates provided/guidance on creating messages Based on building emergency type and technology used to disseminate the message Audible, text & even twitter examples Guidance on Emergency Message Testing The effectiveness of the emergency message Usability, Paraphrase, Readability 33

Barriers to Effective Emergency Response Perception Occupants need to perceive the warning before they take action Factors that inhibit this process: Attention Hearing impairments Visual impairments

34 Barriers to Effective Emergency Response Perception Occupants need to perceive the warning before they take action Factors that inhibit this process: Attention Hearing impairments Visual impairments Situational conditions (sleeping, drug/alcohol impaired) Building may be equipped with audible and visual distractions Comprehension Understanding the information provided by the Emergency communications system Belief in Information Personalization of Information Protective Action 34

Emergency Communication Strategies Alerts Imperative to disseminate an alert to let building occupants know that a warning message will follow Audible Sounds or series of sounds or words or series of

35 Emergency Communication Strategies Alerts Imperative to disseminate an alert to let building occupants know that a warning message will follow Audible Sounds or series of sounds or words or series of words Warning Meant to provide information to building occupants on the state of the emergency and what they are supposed to do in response to that emergency Message Content should be specific, consistent, certain, clear and accurate 5 Important topics to cover in the message 1. Who is providing the message? 2. What should people do? 3. When do people need to act? 4. Where is the emergency taking place? 5. Why do people need to act? 35

EASE Evac Voice evacuation design software from AFMG Intuitive tool for designing acoustic mass notification concepts in a room, hall or building complex 3D simulation software

installers to meet new intelligibility code requirements with pre-planning Saves time and money by reducing costly post-installation changes and limits over-design Powered by AFMG's

37 EASE Evac Voice evacuation design software from AFMG Intuitive tool for designing acoustic mass notification concepts in a room, hall or building complex 3D simulation software calculates the distribution of direct sound levels as well as total sound levels Signal-to-noise ratio (SNR) Speech intelligibility (STI, ALCons, CIS) Benefits Enables designers and installers to meet new intelligibility code requirements with pre-planning Saves time and money by reducing costly post-installation changes and limits over-design Powered by AFMG's proven EASE professional sound design technology, EASE Evac is scaled specifically for life safety professionals. Wheelock speaker data files are available for download at

38 EASE Evac Files Software Tools Quick Link on Home Page Cooper Industries > Cooper Safety > Cooper Notification > Resources > Design Center/Tools > Software Tools 38

39 Intelligibility Solutions Page Resources Tab White Paper and Links to Wheelock Exceder LED High Fidelity Speaker line and HPSA Documentation 39

40 Intelligibility References NFPA Chapter 3 Definitions Chapter 7 Documentation Chapter 14 Inspection, Test & Maintenance Chapter 18 Notification Appliances Chapter 24 Emergency Communication Systems Annex D Speech Intelligibility Supplements 2 Voice Intelligibility for Emergency Voice/Alarm Communication Systems Other Documents B. Crandall, The Composition of Speech, Phys. Rev. 10 ser. 2 (1917): 75. Schifiliti, R.P., Speech Intelligibility, NEMA Supplement, Fire Protection Engineering, Society of Fire Protection Engineers, Issue No. 16, Fall Geoffroy, N.A., Measuring Speech Intelligibility in Voice Alarm Communication Systems, Master s Thesis, Worcester Polytechnic Institute, 5 May Jacob, K.D. & Tyson, T., Computer-Based Prediction of Speech Intelligibility for Mass Notification Systems, SUPDET 2008, Fire Protection Research Foundation, Mar Jacob, K.D., Understanding Speech Intelligibility and the Fire Alarm Code, presentation at NFPA WSCE, Anaheim CA, 14 May Casey Grant, Intelligibility of Fire Alarm and Emergency Communication Systems Fire Protection Research Foundation, Nov Erica D. Kuligowski, NIST Technical Note 1779, General Guidance on Emergency Communication Strategies for Buildings, Fire Research Division, Engineering Laboratory, February

LED Technology LED Strobes Closely controls and manages the light source and output Maximizes human response to a light pulse Optimizes light based on parameters of area and perception of human eye

42 LED Technology LED Strobes Closely controls and manages the light source and output Maximizes human response to a light pulse Optimizes light based on parameters of area and perception of human eye Ideal to have light on for longer period of time vs. intensity of light Perception of brightness to the eye depends on how long the light is on Light source life*: 50,000 to 100,000 hours Xenon Strobes Light can t be controlled Flash only Light source life*: 1000 to 5000 hours * Assuming Steady Operation 42

43 Recent Studies on Strobe Lighting Performance Objectives for Light Sources Used in Emergency Notification Appliances Fire Protection Research Foundation - May 2012 Background: LED and other energy saving technology entering the marketplace Existing requirements are based on relatively short duration, high peak intensity flashing lights NFPA 72 and other standards define a method for calculating the equivalent or effective intensity of a flashing light source Current calculation method is subjective, does not produce an exact comparison and only approximates the perceived brightness for direct viewing of the light source Objective: Develop methods and criteria to evaluate performance of light sources used in emergency notification appliances for inclusion in NFPA 72 Recommend specifications for both direct and indirect signaling as well as identify gaps in the available information 43

44 FPRF Light Sources Study Preliminary Findings Present requirements for visual signals may not be sufficient for waking individuals Maximum luminous intensity from a flashing signal may be a more predictive measure of detection performance under indirect viewing conditions When ambient light levels are high, indirect viewing becomes much more difficult. This might affect placement Requirements for white/clear light color in sleeping areas may restrict the amount of light transmitted by the eyelid compared to amber light Ambient light levels can affect the conspicuity of visual signal appliances, especially for outdoor applications Research Recommendations Awakening Sleeping Persons Direct Detection Indirect and Peripheral Detection Performance-based Alternative ( fc) 44

45 Recent Studies on Strobe Lighting Parameters for Indirect Viewing of Visual Signals Used in Emergency Notification Fire Protection Research Foundation (FPRF) May 2013 Presented at NFPA Conference on June 10 Background: Research recommendation from the May 2012 Study Effective intensity may not be predictive of visual detection of signal lights when these are viewed indirectly or in the far peripheral field of view Observers see the change in illuminance on room surfaces rather than the flashing light itself when it is not in the central field of view Flashing light should increase the illuminance on the opposite wall by at least 7% in order for this increase to be detected reliably Objective: Conduct a human factors laboratory study to identify whether the 7% increase in light level can be reliably detected by observers with normal vision. 45

46 FPRF - Contour Plot: Detection LED LED s Higher Pulse creates greater opportunity to see the light. Xenon 46

47 FPRF - Contour Plot: Ease of Detection Ratings +2 Very Easy +1 Somewhat Easy 0 Neither Easy or Difficult -1 Somewhat difficult -2 Very difficult -3 Not detected Human response to the 100 ms pulse width was far superior 47

48 Questions Contact Information Ben Thomas District Manager South Central Region Cell:

Fire Alarm Intelligibility. Chris Nolan

Fire Alarm Intelligibility. Chris Nolan Fire Alarm Intelligibility Chris Nolan chris.nolan@honeywell.com 416-525-9898 Fire Alarm Intelligibility Agenda Definition Codes Factors Design Test 2 What is Voice Intelligibility Definition: A measure