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Signal Quality Check: Part 1/3 - Measuring SNR
Steps to measure SNR:
1. Wear the TWS mockup. Make two recordings of the VA signal:
a) Silence Recording : 10 seconds of silence
b) Speech Recording : 10 seconds of speech (wearer is talking, e.g. reciting Harvard Sentences)
2. Bandpass both recordings with a bandpass filter (120Hz - 2kHz, 30dB/octave)
3. Compute the following:
a) Compute RMS of Silence Recording
b) Compute RMS of Speech Recording
c) Calculate Voice RMS from previous two results
)
d) Calculate SNR in dB
)
In a good TWS mockup with normal voice loudness, measured SNR should be >>6dB.
8
Noise, RMS
Total Noise + Speech, RMS
RMS
SNR
Vesper - Confidential
noise
2
= sqrt( RMS
– RMS
voice
total
= 20·log
( RMS
dB
10
voice
total
2
noise
/ RMS
noise
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