i'm trying to understand the fir1 filter but i still don't get it. For example here i got an audio signal that i consider noise, i'm passing it through a low pass filter.
n = 100000 fs = 11025 handles.noise = wavrecord(n, fs, 'double'); nfilt = fir1(11,0.4); fnoise = filter(nfilt,1,handles.noise);
Why did i need to pass the noise signal to a low pass filter in the first place? and why is the number of coefficients 11? also the 0.4 shouldn't it be a range of values?
I know these are a lot of questions but when i get to understand them, ill be grateful to everyones help.