My father's in his mid 70s and his hearing isn't very good in the frequency range that would be useful for finding his vacuum leaks.
I was thinking about setting him up with a directional microphone and a pitch-shifter app to bring environmental sounds down a couple octaves so he can hear them. There are tons of Android/iPhone apps that will pitch-shift in post, but none of the trial/freemium ones seem to work on a realtime monitor stream, especially on an external USB (UAC) microphone. I don't want to start buying dozens of apps just to try them.
Any app suggestions or other ideas for him?
