An auditory hallucination is the experience of hearing spontaneous and imaginary noises.    The most common examples of this include hearing clips of sound such as imagined music,   voices,        tones,  popping,   and scraping,  but can also be an infinite variety of other potential noises that are stored within one's memory.
In terms of their behaviour, these sounds will often be based on noises that were expected to occur or have been genuinely heard on a frequent basis within the external environment. For example, a person may repeatedly hear a knock at the door when they are expecting a visitor or hear music they were listening to earlier on in the day. However, at other times, auditory hallucinations may also present themselves as completely new or unusual sounds unlike anything that could currently occur within the external environment.
Auditory hallucinations are often accompanied by other coinciding effects, such as auditory distortion    and auditory enhancement   . They are most commonly induced under the influence of moderate dosages of hallucinogenic compounds  , such as psychedelics, deliriants, and dissociatives. However, they can also occur less commonly under the influence of stimulant psychosis, cannabinoids, and during sleep deprivation.  
This effect can be broken into two specific subtypes, which are described and documented below:
Internal auditory hallucination
An internal auditory hallucination is the perception of hallucinated audio that sounds as if the specific location of its source does not have a particular sense of distance or direction attributed to it; instead, the sound originates from within a person's own head. This is in contrast to external auditory hallucinations, which sound as if they are occurring seamlessly within the external environment as if they were physically present.
The experience of this effect can be broken down into three distinct levels of intensity. These are described and documented below:
Partially defined hallucinations
Fully defined hallucinations
External auditory hallucinationh
An external auditory hallucination is the perception of a hallucinated noise that occurs seamlessly within the external environment as if the specific location of its source has a particular sense of direction and distance attributed to it. This is in stark contrast to internal auditory hallucinations that sound as if they occur exclusively within one's own head.
This effect is capable of manifesting itself across the 3 different levels of intensity described below:
Partially defined embedded hallucinations
Partially defined separate hallucinations
Fully defined separate hallucinations
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