I always have mine with me, but don't always have occasion to use it, especially on my main commute, where I've tailored my route to minimize interaction with cars.

It's also a good way to gauge your risk - it's easy to remember how many times you honked.

When I've yelled at errant drivers, they either didn't care, got annoyed, or mocked me in response and continued - if they could hear me at all. The airzound is more likely to stun them into stopping or staying in their lane, as they wonder "what was that?!"