Audioless dreams?

I was talking to my friends about dreams after watching Inception and the differences in our dreaming. Then one of my friends said that she usually remembers her dreams, but that they're all audioless, and sometimes even in black-and-white. She also said that they're fairly eventless as well, more than often just depicting a scene out of her everyday thoughts - like, one time, she replayed a conversation she had had with me during the day about school, only there was no sound, only our mouts moving. But she still knew what we had said anyway, so it wasn't as though she needed it to understand, she said.

I found this rather odd. I've heard of simple dreams, but can you really have audioless dreams? She has no problems with her hearing whatsoever, so it's not that. Is it possible to have dreams without sound, and color? Or does she simply not remember it?

Some of my dreams are "eventless" as you'd describe it, but in most of them, something wierd or cool happens. Maybe hearing audio just depends on the imagination of the person, and the vividness of the particular dream. I'd say she just isn't remembering all the details.