Originally Posted by 101101
This gives me an idea: would it possible to put in a high / low pass filter to allow only human voice to pass through? I'm not a DSP guy, but maybe I can talk to some of the electrical engineers I work with and see if this is possible.
Edit: Oh, I tried adjusting the gain on the way home from work and my sister claims it didn't make any change.
Tried a little analysis this afternoon while visiting my parents. I had my sister plug her phone (headphone jeack) into my computer (audio line in) and record a phone call when I called her while driving. Loaded the .wav file into MATLAB and tried lowpass and bandpass filters in MATLAB at varying frequency cutoffs and basically came to the conclusion such an approach wouldn't work. Maybe I didn't find the right frequencies to make my high / low cutoffs, but I couldn't get a clear sound. This basically translates into not being able to use an inline bandpass filter like I'd hoped to.
If it's not raining tomorrow (forecast claims it will) I'm going to look closer at the car and see if there's some mechanical fix to this.