Public Safety Audio Quality
Modified Rhyme Test
SAMPLE AUDIO FROM TEST
Four types of radio systems were tested: two analog — 25 kHz and 12.5 kHz — and two digital — Baseline IMBE vocoder and Enhanced IMBE vocoder (both used by P25). Following are just a few samples from the test.
No mask with no additional noise
P25 with Baseline Vocoder |
P25 with Enhanced Vocoder |
12.5 kHz Analog FM |
|
No mask with firetruck pump panel
P25 with Baseline Vocoder |
P25 with Enhanced Vocoder |
12.5 kHz Analog FM |
|
(4 dB S/N) |
(4 dB S/N) |
(4 dB S/N) |
Not Tested. |
SCBA mask with no additional noise
P25 with Baseline Vocoder |
P25 with Enhanced Vocoder |
12.5 kHz Analog FM |
|
SCBA mask with two PASS alarms sounding
P25 with Baseline Vocoder |
P25 with Enhanced Vocoder |
12.5 kHz Analog FM |
|
(-2 dB S/N) |
(-2 dB S/N) |
(-2 dB S/N) |
Not Tested. |
SCBA mask with in-mask low-air alarm sounding
P25 with Baseline Vocoder |
P25 with Enhanced Vocoder |
12.5 kHz Analog FM |
|
(15 dB S/N) |
(15 dB S/N) |
(15 dB S/N) |
Not Tested. |
SCBA mask with 2.5-inch fog nozzle
P25 with Baseline Vocoder |
P25 with Enhanced Vocoder |
12.5 kHz Analog FM |
|
(9 dB S/N) |
(9 dB S/N) |
(9 dB S/N) |
Not Tested. |
SCBA mask with rotary saw cutting metal door
P25 with Baseline Vocoder |
P25 with Enhanced Vocoder |
12.5 kHz Analog FM |
|
(4 dB S/N) |
(4 dB S/N) |
(4 dB S/N) |
(4 dB S/N) |
Amplified SCBA mask with rotary saw cutting metal door
P25 with Baseline Vocoder |
P25 with Enhanced Vocoder |
12.5 kHz Analog FM |
|
(4 dB S/N) |
(4 dB S/N) |
(4 dB S/N) |
Not Tested. |
SCBA mask with chainsaw cutting wood
P25 with Baseline Vocoder |
P25 with Enhanced Vocoder |
12.5 kHz Analog FM |
|
(5 dB S/N) |
(5 dB S/N) |
(5 dB S/N) |
Not Tested. |
