Company culture of not talking about earnings only helps the company. It allows them to pay lowest market value for anyone, under the (often true) hopes that they don't know their value. In short talk about it, and get other people to talk about it.
I would talk with your co-workers get them to open up about what they make, or have the breach subject in the conversation group while the other person can hear. Talk about what you used to make and what you make now. The key if to give everyone more context. Its important to remember that someones value as a person is not their market price.
The more information a person has available, the better the choices they can make.
[$47/hr, 2 years out of college, east coast]