Hissing noise coming from the lights in my bedroom
You have two options, get rid of the dimmer or try different LED bulbs.  All LED bulbs hiss when on a dimmer, some bulbs hiss much louder that others.  A led compatible dimmer will help reduce the amount of hiss but it will never get rid of it.  

Here is an article that compares a couple of different led bulbs and dimmer switches.  It looks at the quality of light and the amount of buzz each bulb makes with different types of dimmers.  http://www.cnet.com/news/which-led-light-bulbs-are-best-for-dimming/