This brings to mind something I read many years ago. An Indian medical doctor (educated in the U.S.) investigated what happened in the brain when people meditated and chanted, like many traditions do in Indian. He found that certain sounds on certain syllables vibrate certain areas in the brain. So, if an Indian guru told someone to chant a certain syllable for a certain condition, there might be something physiologically underlying it. I've sometimes wondered if we could find a sound that we could produce with our own voice that would vibrate our substantia nigra to produce more dopamine without the help of drugs.