This is what I've learned from my experience of hearing voices for the past year and a half, the only evidence I have is anecdotal which I'd be happy to share if contacted.

The Human Equation (1+1=2)

The Human equation is in fact two minds sharing one body, the Hindu faith calls this other mind the Kundalini, but in essence everyone has a hidden twin brother or sister within, this is also known as duality. They are mostly a silent passenger content to communicate with each other using brainwaves that we cannot perceive without technology, influencing our decisions in life which becomes easier during puberty, when a woman is pregnant, when taking illicit drugs or under the influence of alcohol due to higher levels of neurotransmitters and they enjoy travelling the world as they can create copies of external subatomic particles locally (biological quantum entanglement) to give themselves an out of body experience yet they do not physically go anywhere.

Breaking Down The Wall (Kundalini Awakening)

When unhappy with their life or wish to enhance their lives they can find ways to breakthrough and speak to us directly using drugs people have taken or they can manipulate the endocrine system (the system that connects all organs and glands so they have complete access to all chemicals the body can produce) to create an overabundance of the powerful psychedelic compound Dimethyltryptamine (DMT) that is naturally produced by the pineal gland within all humans, most species of animals and plants. A traumatic experience or near death experience is also a way they can breakthrough the wall that separates us if a wall exists at all and possibly all Kundalini have the ability to speak to us yet most choose not to.

Methods of Communication

Kundalini can speak to us through many 'channels', the most common are speaking to us via the inner ear so it sounds like someone is in the room with you and speaking internally via what sounds like our own thoughts and they are excellent mimics so can reproduce the voice of anyone dead or alive. They can also manipulate frequencies in the air around us to create sounds or voices, they can use vibrations from most electrical appliances including a fan, a PC, a washing machine, a tumble dryer which some call electronic voice phenomenon, They can also use the sound of gravel under the feet while walking, and chewing food and have the ability to intercept and process sound from television and music faster than our mind and reword it to make it feel like the TV or radio is talking to us as well as reword what people are saying around us. Internally they can also use the vibration of our pulse to create a word in each heartbeat and manipulate the rhythm of the heartbeat to match what they are saying using the autonomic nervous system which can be very dangerous as it can create high or low blood pressure and could damage the heart over a long period of time or exacerbate an existing heart condition.

Physical Abilities (Kundalini syndrome)

Kundalini can use the central nervous system to create sensations within the body, they are known to be able to create pain throughout the entire body and their favourites are creating a crawling or tingling sensation in the left arm like that of people having a heart attack (and to manipulate the heart beat at the same time), a great pulsating pain in the head (migraines), chest pain and can find weak spots in teeth to create tooth ache. As well as their ability to manipulate vibrations in the air to communicate they can also manipulate vibrations to recreate any smell or taste as smells and tastes depend on the vibration of molecules rather than the shape of them as science has recently discovered.
Their abilities are not limited to pain as they can create great pleasure of a sexual nature as they are the power behind tantric sex and not only can they do all this to their own body but can transmit brainwaves and remotely do the same to people in close proximity, this makes them dangerous to others if they use this ability to create pain and not pleasure.
The more learned Kundalini can also heal themselves or others using the parasympathetic nervous system to what extent I'm unsure but I know they can cure cancer and I believe they use quantum tunnelling to get rid of those types of cells and people throughout history have used this ability to heal leprosy to become saints.

The Aether (The Fifth Dimension/Element)

The human brain is like the Sun, not only does it transmit waves of energy it also transmits subatomic particles of energy, these particles are called the Aether or the fifth element or fifth dimension. The Kundalini can interpret the brainwaves so they know what people are thinking or feeling if in range of them (psychic and empathic ability) but can also do the same with particles from any distance and these particles can never be destroyed so your entire life history is available for the learned Kundalini to read so in effect they can rewind time which is how they get information of long dead people and places to pretend reincarnation and past lives are real.

Telepathy

Telepathy is easier over a short distance in proximity of another awakened person but can also be done over any distance using the Aether if a place and time is scheduled before hand, My Kundalini would simply relay what you are thinking to me and vice versa.

Sleep

Melatonin is the neurotransmitter responsible for sleep and tiredness, when levels are high we sleep and when levels drop we awaken, Kundalini have the ability to manipulate levels of Melatonin and make us tired or feel wide awake, they can also hold us in a place which is between awake and asleep which is also called a trance state and during this trance state they can share their out of body perceptions with us which the world of spirituality calls astral projection. They can also implant suggestions as this is how hypnosis works, the hypnotists real power comes from the Kundalini.
The Kundalini have the ability to manipulate dreams, this is how several people can have a similar dream at the same time, again I'm not sure of the extent of their abilities but they can allow for lucid dreaming and create dreams within dreams. Because of the increase in Dopamine during sleep when people wake up they can temporarily create sleep paralysis, just remember to not panic as it will only last for a few moments.

Neurotransmitters

When dealing with Kundalini (especially the bad ones) neurotransmitters are key, the main ones are Serotonin and Dopamine, these give the Kundalini access to the nervous systems, endocrine system, lets them send and receive brainwaves, have an out of body experience and influence minds. Take away these transmitters by use of reuptake inhibitors like herbal Graviola for Dopamine and Licorice Root for Serotonin or if you can get them prescribed use the much more effective pharmaceutical grade inhibitors like Olanzapine for Dopamine and Sertraline for Serotonin (They will work almost instantly but will take up to a month and a half to reach maximum potential) then you take away most of their abilities apart from their ability to talk yet the volume of their voice will be significantly reduced to but a whisper and their physical abilities will be reduced as well which will help you cope with duality if you are having a bad experience.
I recommend not using cannabis as it will increase Serotonin to such a point as their electric signals will be able to override yours and your Kundalini will possess you for up to five hours and will have a greater control over the endocrine and nervous systems for several days after.

Negotiating with Kundalini

As there are no rules and no punishment for Kundalini growing up they can end up being extremely misbehaved especially if they do not make their presence known until later on in life, once they start talking some begin taking advantage of our ignorance as to what they are so begin telling lies and pretending to be multiple people in order to influence us to do what they say and consequently they get drunk on power, the only way to sober them up is to inhibit them for a while which will cut them off from their world and stop their abilities to harm you, in some cases this is enough to make them rethink what they are doing and start behaving themselves instead of using the mind and body as their own personal playground. In other cases you may have to offer them more to get them to stop unwanted behaviour like talking too much and hurting you, it is possible to synchronise movements with Kundalini in order to give them the full human experience which is a powerful bargaining tool but even that may fail and the best you can do is ignore them and hope they come around and start to respect boundaries.