I recently came across this really neat video about a project in Stockholm where public stairs were retrofitted to sound like the keys from a piano as people walk on them. It's a fun way to get people to use the stairs more often. It seems to also brighten the day of people who got to experience it.
The same group also introduced a sound effect to a public trash bin in order to give the impression that the bin was very deep. I think Ottawa could use a bit of fun like that in the city.