Sound Pressure level returning -inf

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Farid
Farid 2022-9-1
回答： Jimmy Lapierre 2022-9-7
Hello Community;
when I use the function [Lt,Leq,Lpeak,Lmax] = SPL(recording_vector) it returns vectors containing (partially or completely) -inf values. Surprisingly when I re-Run the same line I get usual numeric values. how is this possible? how to avoid it?
Thanks
  2 个评论
Chunru
Chunru 2022-9-2
Can you show your data (a portion) or your code?
It is likely due to the signal amplitude to be 0 so log of it becomes -inf.
Farid
Farid 2022-9-3
Thanks a Lot Chunru, I am attaching the file to this comment.
calib=importdata('calib.mat')
IRS=importdata('IRS.mat')
spl = splMeter("CalibrationFactor",calib, ...
"FrequencyWeighting","Z-weighting", ...
"TimeWeighting","Fast", ...
"TimeInterval",0.125, ...
"SampleRate",FS,...
"Bandwidth","1 octave");
[Lt,Leq,Lpeak,Lmax] = spl(IRS)

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采纳的回答

Jimmy Lapierre
Jimmy Lapierre 2022-9-7
Leq, Lpeak and Lmax are only computed every TimeInterval, so they correspond to the SPL of zero for the first 0.125 seconds. And as chunru said, that corresponds to -Inf. When you call spl a second time, you are already pass the first 0.125 seconds of pure silence.
To avoid it, either discard the fist 0.125 seconds, or set a minimum value you prefer.
For example set any value below -100 dB (including -Inf) to -100:
Leq(Leq<-100)=-100;

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