Autonomous voice communication
Autonomous voice communication can be described as the experience of being able to hear and converse with a disembodied and audible voice of unknown origin which seemingly resides within one's own head.      This voice is often capable of high levels of complex and detailed speech which are typically on par with the intelligence and vocabulary of ones own conversational abilities. As a whole, the effect itself can be broken down into 5 distinct levels of progressive intensity, each of which are described below:
- A sensed presence of the other - This level can be defined as the distinctive feeling that another form of consciousness is internally present alongside that of one’s usual sense of self. This sensation is often referred to within the scientific literature as a “sense of presence”.
- Mutually generated internal responses - This level can be defined as internally felt conversational responses to one’s own thoughts and feelings which feel as if they are partially generated by one’s own thought stream and in equal measure by that of a separate thought stream.
- Separately generated internal responses - This level can be defined as internally felt conversational responses to one’s own thoughts and feelings which feel as if they are generated by an entirely distinct and separate thought stream that resides within one’s head.
- Separately generated audible internal responses - This level can be defined as internally heard conversational responses to one’s own thoughts and feelings which are perceived as a clearly defined and audible voice within one’s head. These can take on a variety of voices, accents, and dialects, but usually sound identical to one’s own spoken voice.
- Separately generated audible external responses - This level can be defined as externally heard conversational responses to one’s own thoughts and feelings which are perceived as a clearly defined and audible voice which sounds as if it is coming from outside one’s own head. These can take on a variety of voices, accents, and dialects, but usually sound identical to the person’s own spoken voice.
The experience of communicating with hallucinated voices has been well established with and without the use of hallucinogenic drugs through scientific study. For example, one study successfully demonstrated that anybody can encounter a dialogue between themselves and a voice of unknown origin under the influence of psilocybin mushrooms. This study interviewed 128 participants with an approximate total of 3,427 psilocybin mushroom experiences between them and revealed that 35.9% (46) of the participants reported voices whilst 64% (82) did not.  Even outside of these drug-induced experiences, hearing voices within one's head is a well documented psychological phenomena and can in and of itself, generally be considered as a relatively harmless state of mind to find oneself in. 
- Woods, A., Jones, N., Alderson-Day, B., Callard, F., & Fernyhough, C. (2015). Experiences of hearing voices: analysis of a novel phenomenological survey. The Lancet Psychiatry, 2(4), 323-331. | https://doi.org/10.1016/S2215-0366(15)00006-1
- Hearing voices | https://www.mentalhealth.org.uk/a-to-z/h/hearing-voices
- Basic Information About Voices & Visions | https://www.hearing-voices.org/voices-visions/
- Romme, M. A. J., Honig, A., Noorthoorn, E. O., & Escher, A. D. M. A. C. (1992). Coping with hearing voices: An emancipatory approach. The British Journal of Psychiatry, 161(1), 99-103. | https://doi.org/10.1192/bjp.161.1.99
- How the Brain Can Hear Voices That Don't Exist (PsychologyToday) | https://www.psychologytoday.com/us/blog/the-guest-room/201507/how-the-brain-can-hear-voices-dont-exist
- The sensed presence effect (Scientific American) | https://www.scientificamerican.com/article/the-sensed-presence-effect/
- Fénelon, G., Soulas, T., De Langavant, L. C., Trinkler, I., & Bachoud-Lévi, A. C. (2011). Feeling of presence in Parkinson's disease. Journal of Neurology, Neurosurgery & Psychiatry, jnnp-2010. | https://dx.doi.org/10.1136%2Fjnnp.2010.234799
- Experiences of continued presence: On the practical consequences of ‘hallucinations’ in bereavement. | http://www.leudar.com/pdfs/voices/Hayes&Leudar2013.pdf
- Listening for the Logos: a study of reports of audible voices at high doses of psilocybin | http://www.maps.org/news-letters/v07n1/07112bea.html
- In Your Head: Hearing Voices | http://www.psychologytoday.com/articles/200701/in-your-head-hearing-voices