The backspace key on most keyboards has a very distinct sound. Not to mention it's positioning means timing will be noticeably different as well. Might be better off mixing in a few meaningless modifier keys (press Ctrl, Alt or Caps Lock).
Unless the gibberish is the same every time, the repeated sound of your password will still be parsable from a long enough sound recording of your computer usage.
I think it is more accurate to say that the gibberish is unlikely to _always_ be the same.
I think one can tend to create similar gibberish over time. I've worked on a system where I needed to do a new signup every time I wanted to test a feature and I've run into issues where the gibberish I entered matched an account that I had previously created.
Yep! Always a bit of fun when someone goes to use my laptop for an end-of-sprint presentation and types a bunch of gibberish infront of all the stakeholders :D
