When I was talking with people about how some badges use two pins of the attiny, I basically explained it to myself while trying to explain to others why it would be louder. Instead of just pushing the speaker from the resting position, you also pull it back, when connecting both the inverted oscillator pins to a speaker. Now at the airport and thanks to seeing Charles Lohr at the supercon, I remembered that he actually did that. I need to further hack that bodged prototype I guess :D

https://www.youtube.com/watch?v=__ECzxnvEg8