The human body has energy centers with different rates of vibration or sound. These energy centers are called charkas. These energy centers are not in the human body. Rather they are in what is called the subtle or astral body - the aspect of us that experiences astral travel, out of body experiences, and lucid dreams. The subtle or astral body is an energetic form of the physical body.
There are several chakras in the subtle body, but there are 7 main charkas. Their location corresponds to the human spine starting at the base of the spine and running to the crown of the head. Each of the 7 main chakras correspond to the seven notes on a musical scale (C, D, E, F, G, A, B). And each chakra also has a corresponding color (seven colors of the rainbow - red, orange, yellow, green, blue, indigo, violet). Colors, like sound/vibration, can have an impact on our body's energies. They can help to clear negative emotions and energy and restore balance. See the chart below for the corresponding color and note for each chakra.
Each chakra refers to a certain level of energy vibration and in the various chakras the physical and emotional aspects of a human being come together. For example, when one is healthy or sick, angry or happy, sad or glad, depressed, hateful, mean, hating people and life, or content with life, happy, loving, caring etc., etc. all this reflects whether the chakras are blocked, or vibrating smoothly. It also indicates which chakra or chakras are dominant in a persons life.
There is an entire science behind working with the chakras and cleansing them so the human body, mind, emotions, and soul run smoothly, efficiently and are in harmony not only within oneself, but the person as a whole is at peace with others. All the commands, ethics, and moral codes in all ancient and modern religions are methods that are used (unconsciously) to cleanse and balance the chakras. Certain yoga techniques (such as pranayama and/or chanting mantras) are used to raise the quality of the energy vibration in specific chakras.
Side Note: It is worth noting that sound (creating certain vibrations using your voice) stimulates the chakras. While in a state of deep meditation ancient seers in India came up with different mantras for stimulating the different chakras. The chakras affect the health and emotions in the region of the body that they govern. By using the correlating mantra you can stimulate the chakra to help heal the body, and release the emotions.