I saw this thread a couple of weeks ago but I've been too busy to play around with the idea until this morning. Here's my try at it. (These are WAV files. I'm fairly new to Android so if they should be in some other format let me know.)
I've included the original in case anyone wanted it. Then I have it shifted up an octave. Then I mixed the two together.
I'm still playing around with this idea. An octave is easy - it's just double the frequency. If I can find the right pitches in between I want to make a harmonizing chorus of droids. Barbershop quartet droids!
Gimme some time.
Here ya go.
I cut the volume of the high pitched one down to 50%. I think it sounds about right but it might be too soft now. Honestly, I've been messing with it too much to tell anymore.
I don't mind tweaking it some more, so let me know what you think.
Copy to your media card.. Android index all sounds/music.. what I did was create a folder called Media and inside called Notifications.. i put it there and then when I went Gmail, went to notifications and the new sound was there.