low pass band filter

how do I use the low pass band filter? I have a wave that I want to use a lowpass band filter on at 325 Hz. I know how to splice the wave at the appropriate points, but I don’t know how to apply the filter. When I apply the low pass band filter at 325 Hz using the drop down menu, I can still understand the portion I am filtering. The point is to not understand the portion of the wave, but to still hear the inflection. This is for an experiment in prosody. I am replicating a previous experiment where this was applied.

Find out what filter they actually used, and then you might be getting somewhere. “low pass band filter” doesn’t mean anything specifc, apart from the idea that it lets through lower frequencies and rejects higher ones. 325Hz tells you where the centre of the change is, but not how steep the transition is, or by how much the higher frequencies are attenuated.

What you really need is a frequency response graph for the filter you are trying to replicate, and then use the Equalisation effect to replicate that curve, and apply that (in 1.3.4 you can save the curve for future use).