matlab - Resample and anti-alias FIRLS filter order -

i have audio files recorded in 48khz sampling frequency. have examine audio characteristics , need lower sampling frequencies see when start fail. going test downsampled audio files @ 24khz, 16khz, 12khz, , 8khz.

i found matlab function resample(x,p,q,n). it's easy understand there's 1 thing i'd ask. in description says applies anti-alias firls filter during re-sampling process. understandable. don't know should apply n because accuracy depends on n parameter. values should use obtain decent results in downsampling. help.

also, says if downsample high low sampling frequency should in intermediate stages. suggest on this. cheers! :)

you can use easier command y = decimate(x,r)

the documentation mentions "for better results when r greater 13, divide r smaller factors , call decimate several times.", highest factor of 6 times decimating don't have worry.

the default 8th order iir , 30th order fir seem sufficient me, if doubt them can plot decimated signal on original , increase order see effects.