Pink noise is generally referred to when the audio is less harsh in nature or lower in volume. Blue noise is a term I personally use to describe enhanced filtered white noise audio which is generally softer in volume and made pleasant to the ear by varying the frequency to some degree. Some research seems to indicate that enhanced white noise played at comfortable low levels can create an atmosphere of relaxation. If played at bed time, some believe there is a positive influence on their sleep. If just played casually in the background, it may even cultivate a sense of well being.
Some companies producing white noise recordings include subliminal messaging.
These are spoken audio messages which are played beneath the level of the white noise and the producers claim can only be heard by the human subconscious. They suggest these subliminal audio messages will reprogram the subconscious in order to control emotions, appetite, cravings, and harmful habits such as smoking. I do not use subliminal messages because I do not believe such is necessary. If you can obtain just a little assistance in gaining physical relaxation in a stressful life, or some help in falling to sleep at night, or if you can develop the feeling of well being through simple concentration and breathing techniques, I believe all the other things faced in life will be easily managed. Besides, the last thing I want is for someone to be whispering in my subconscious ear telling me things with which I may not agree.