|
[33]
|
Time
|
Electret condenser microphone
|
2
|
LMS-ANC
|
External noises are reduced by 12.92–16.11 dB
|
|
[34]
|
Time
|
Electronic stethoscope
|
1
|
Single input ANC
|
Most of breath sounds and noises are suppressed, performance robust to heart beat rate
|
|
[35]
|
Time
|
Microphone
|
1
|
LMS-ALE, RLS-ALE
|
HS recovery and noise reduction are 91–93% and 89–92%, respectively, for LMS-ALE; for RLS-ALE, they are 95–97% and 90–92%
|
|
[36]
|
Time
|
NA
|
NA
|
Variable step size Griffith LMS-ALE
|
The SNR gain is 7.85 dB
|
|
[37]
|
Frequency
|
Audicor system [38]
|
2
|
SS, FFT
|
Better noise removal; improved ability to detect S3 and S4 sounds
|
|
[39]
|
Frequency
|
Electronic stethoscope with electret microphone
|
1
|
DWT, Hilbert transform
|
Recommendations on optimal parameters selection are given
|
|
[40]
|
Frequency
|
Microphone
|
1
|
DWT, LMS-ALE, RLS-ALE
|
RLS-ALE and DWT with SURE shrinkage give best results
|
|
[41]
|
Frequency
|
NM
|
NM
|
EMD
|
EEMD seems to be a good solution for HS denoising
|
|
[42]
|
Frequency
|
NM
|
NM
|
EMD
|
S1 and S2 can be extracted with high accuracy
|
