1. The Importance of In-Mask Communications
Harvey David Chambers, Motorola Solutions
This is not a technical review of BT technology
This is about understanding the fire ground environment and its impact on communications and the available technology and BPs to address communications issues

2. Agenda Radio Audio Quality Overview IAFC Best Practices
SCBA Audio Performance
Technology Solutions for Fire Ground

3. Preface Be Proactive Information is the Key
Towards Radio Audio Quality
Anticipate Possible Audio Issues
Vs. being REACTIVE when audio “issues” arise
It’s an Investment
Information is the Key

4. Radio Audio Quality Overview
Audio Quality vs. Intelligibility
Audio Quality
Very, VERY subjective
What sounds good to one person is different for another
Preference, Hearing loss, Operational needs
Intelligibility
Main Goal in Extreme Environments
Can you understand the radio message?
Humans can fill the “blanks”

5. Radio Audio Quality Overview
The Challenge:
Creating intelligible radio communications in variable, sometimes high noise and extreme environments while accommodating customer preferences and references

6. Radio Audio Quality Overview
Main Issues Affecting Audio Quality & Intelligibility
Background Noise
Acoustical Feedback
Radio Usage
RF Radio Coverage

7. Background Noise Fire Ground Noise
Alarms
Smoke, Low Air Alert, PASS
Mechanical
Pump Panel, Saws, Fans
Reduction of transmitted speech intelligibility
when operating in a high noise environment
SNR
Signal to Noise Ratio
≤ 0dB SNR (more Noise than Speech) is BAD for a radio vocoder!
Sometimes Difficult and Extreme Situations

8. ↑ Sound Loop Gain, ↑ Feedback
Acoustical Feedback is a Natural Phenomenon
Occurs when a sound loop exists between an audio input (a microphone) and an audio output (a speaker)
↑ Sound Loop Gain, ↑ Feedback
1. The Sound Loop
Exists when a signal received by the transmitting microphone is amplified and passed out of the receiving speaker
2. Further Audio Amplification
Sound from the speaker is then received by the transmitting microphone again, amplified further, and passed out through the speaker again…
MIC
SPKR
3. Acoustical Feedback Results
Radio users hear a more pronounced Echo and “Crickets” (Digital) or Howling (Analog) noise from the received audio

9. Radio Usage Radio Best Practices Accessory & SCBA Design User Voice
Speaking in a loud, clear voice
Annunciation
Radio / Microphone Position
Distance from mouth to microphone port
Angle between mouth and microphone port
Accessory & SCBA Design
Technology
Intended Use Position (IUT)
Microphone Location and Porting

10. Radio Audio Quality Overview
Combination of all these Factors!
Main Issues Affecting Audio Quality & Intelligibility
Background Noise
Acoustical Feedback
Radio Usage
RF Radio Coverage

11. Developing and Maintaining Good Habits for Radio Communications
IAFC Best Practices
In an effort to deliver optimal intelligible audio in the presence of high background noise, the use of “Best Practices” as defined by the International Association of Fire Chiefs (IAFC) along with optimal Customer Programming Software (CPS) audio settings in the radio, have shown to be very beneficial in delivering improved communications.
Using the “IAFC Best Practices”, transmit audio quality and intelligibility can be improved significantly.
Developing and Maintaining Good Habits for Radio Communications
Show of hands for who operates with Scott, MSA, Draeger, Survivair

12. IAFC Best Practices – Section 1
Use the radio for the initial distress call before manual activation of the PASS in a Mayday situation when practical
Ensure that the microphone is placed 1 to 2 inches from the mouth or SCBA voice port with the microphone positioned directly in front of the audio source
Speak in a loud, clear, and controlled voice to maximize audio intelligibility
Shield the microphone from noise sources to improve the intelligibility of the audio in high noise environments
When practical consider using a free hand to muffle a mask-mounted SCBA low air alarm when trying to transmit on a radio
Consideration should be given to the location of radios and microphones in relation to PASS devices and other noise generating user equipment

13. Inverse Square Law
In a free field the intensity of sound drops by 6 dB for each doubling of distance from the source.

14. Noise Level
Distance from mouth to device
Quiet
(office)
Noisy
(Pump Panel)
Loud noise
(Fans, Saws)
5” or less
Confidential talking
Clear normal talking
Loud firm
talking 8”
Loud firm talking
Extra loud
12”
Extra loud talking
Move closer!

15. SCBA Audio Performance
Voice Emitters
Mask Characterization
Level attenuation
Distortion of voice
Show of hands for who operates with Scott, MSA, Draeger, Survivair

16. Voice Emitters
Typically where the best audio quality is produced for radio communications
Scott
MSA
Drager

17. SCBA Mask Characterization

18. Level Attenuation

19. Noise Level
Distance from mouth to device
Quiet
(office)
Noisy
(Pump Panel)
Loud noise
(Fans, Saws)
5” or less
Clear normal talking
Loud firm talking
Extra loud talking 8”
Move closer!
12”

20. Level Attenuation

21. Distortion of Voice

22. Distortion of Voice

23. Technology Solutions Best Practices Noise Suppression
Retractable Microphone Attachment
Noise Suppression
In-Mask Solutions
Bluetooth

24. Technology Solutions Bluetooth Not all solutions are the same Pros
Voice isolation
Acoustical feedback
Best practices
Cons
Battery
Connecting
Audio Features

25. Summary Audio Quality vs. Intelligibility SCBA Best Practices
SCBA Mask Characteristics
Bluetooth Pros & Cons