Using High Pass Filter with script

Do you have Unity Pro? Filters don't work in the indie version. If you have Pro, the effects can be turned on and off with audio.bypassEffects (although the docs aren't clear: bypass should turn the effects off when true, but it seems to do the opposite).
Anyway, I think these filters are useful only if you want to modify the cutoff frequency continuously at runtime. If you don't have Pro but only want to apply the filter at a fixed cutoff frequency, you can have different versions of the audio clip pre-filtered and select the one you want at each time.

Thank you for your answer. I found a way to make it work finally, using the GetComponent function. I have the pro trial version and I had to use this filter in a script as it is a very specific project centered on the sound