Auditory suppression + Dextromethorphan
Dextromethorphan is known to produce auditory suppression, a auditory effect. A dampening of auditory perception in which sounds become muffled, distant, and reduced in both volume and clarity, as though hearing through thick walls or underwater. This creates a cocoon-like sense of auditory isolation.
About Auditory suppression
Auditory suppression, also known as auditory acuity suppression, is the experience of sound being perceived as more distant, quiet, and muffled than it actually is. This effect can significantly decrease both the volume of a noise and its perceived quality and detail, creating a sensation akin to hearing through a thick wall, being underwater, or wearing heavy ear protection. The external world may seem to recede acoustically while internal mental activity becomes relatively more prominent in one's awareness.
The subjective quality of auditory suppression varies depending on the substance and dosage. At lower levels, sounds may simply seem slightly farther away or less crisp, as if the treble frequencies have been selectively reduced while bass frequencies remain more perceptible. At moderate levels, the muffling becomes quite pronounced, with speech becoming difficult to follow and ambient sounds fading into a dim background wash. At higher levels, sounds may seem to come from an enormous distance or may be reduced to faint, indistinguishable murmurs, creating a profound sense of acoustic isolation from the external environment.
Auditory suppression is most commonly induced under the influence of moderate to heavy dosages of dissociative compounds such as ketamine, PCP, DXM, and nitrous oxide, where it is a characteristic feature of the dissociative state. The progressive disconnection from sensory input that defines the dissociative experience naturally includes a dampening of auditory perception, often proportional to the depth of the dissociative hole. It can also occur under the influence of GABAergic depressants such as alcohol and benzodiazepines, as well as certain antipsychotics like quetiapine, where general CNS depression reduces the brain's sensitivity to sensory input.
The experience is distinct from hearing loss in that the physical auditory apparatus continues to function normally. Rather, the brain's processing and interpretation of auditory signals is dampened or filtered, creating a subjective experience of reduced hearing despite intact sensory organs. This distinction becomes apparent when the substance wears off and full auditory acuity returns immediately, unlike organic hearing damage which persists.
Subjective reports frequently describe the experience as simultaneously disorienting and peaceful. Many users, particularly those who find the external world overstimulating, report that auditory suppression creates a welcome cocoon of quiet that allows for deeper introspection and internal focus. Others find it unsettling, particularly when it makes it difficult to follow conversations or remain aware of one's surroundings. In dissociative experiences, auditory suppression often combines with other disconnective effects to create a sense of retreating into an internal space that feels increasingly removed from external reality.
Auditory suppression is often accompanied by other coinciding effects such as auditory distortion, auditory hallucination, physical disconnection, and sedation. The combination with auditory distortion can create surreal perceptual experiences where remaining sounds are not only quieter but also warped, echoing, or pitch-shifted. When combined with internal hallucinations at higher dissociative doses, the fading of external sound can be replaced by internally generated auditory content, completing the transition from external to internal experience.