Default [Q] Mac audio

Hello, almost when ever my mom logs in to her user account on an imac running 10.6.8, noise won't come out of the speakers at any noise level. There are 3 other accounts on the iMac, and they do not have that issue. I found that I can get noise to come out if I stick something like earbuds in and pull it out that the issue is "fixed" until my mom logs out. All help is appreciated my thanks in advance.