Funny you say that... My audio stopped working on my phone recently. I usually have the sound off so I didn't notice it at first. Then, I missed a few calls in the evening even though sound was on and I couldn't hear anything via youtube, "unlock sound" etc. Turned out, there was some corrosion on the bottom plug that made my phone think it was plugged into an external device and handed over operations to said imaginary device. Then, after a few weeks of no sound, I about shit my pants when the loudest "clickly clack clicky clack" sound exploded as I was texting. I was elated! I was intrigued! I could hear again! And so naturally, I immediately turned my keyboard sounds off, switched my phone to silent, and continued about my normal life. Turns out, not having your phone ring is kind of nice.
I always have my phone silenced. It eliminates the awkward phone going off during a meeting or in the library etc. The other day it somehow was switched back on and it rang. -I had completely forgotten that I had a song for my ringtone.