Even when we look at chanting only physically, in order to produce certain sounds you need to aspirate and you also need to use the nose or the throat, etc. So sound engages different parts of our body. If I want to produce a sound with what we call Maha Prana it will cause a contraction of the stomach and thus also works on the internal organs. It is known to reduce weight and even regulate the menstruation of women. One woman had a problem with her menstrual cycles ever since she got it in puberty. She learned chanting and after having chanted regularly for two years her period became well regulated.And as a tool for therapy, especially when we talk about stress, chanting or sound can relax people immensly. It can be a great helper against sleeplessness. I have also worked with mentally retarded children and have seen a lot of positive effects with chanting. Problems like drooling or stuttering can be reduced. Some of the friction sounds like Hram for example can help them so much.