Auditory hallucinations: An audiological perspective

The purpose of this article was to review information on auditory hallucinations from an audiological perspective in an attempt to stir interest across disciplines. Bentall defines hallucinations as perceptions that lack an external stimulus, have the full impact of an actual perception, and are not under voluntary control.¹ Auditory hallucinations have been commonly associated with psychiatric conditions, but this is not always the case. They can be linked to a variety of otological, neurological, and pharmacological disorders. People with AHs perceive a wide range of sounds. Their sound perceptions can be divided into formed and unformed AHs. Formed AHs are more complex, internal acoustic perceptions, such as music and speech. Types of unformed AHs include tones, clicks, chords, etc., which vary in pitch and loudness. In many instances, it is difficult to differentiate unformed AHs from tinnitus. It is difficult to reach definite conclusions regarding the basis of AHs. Theories include reduced neural connectivity (loss of neural connections within the brain), a pathophysiological generator in the auditory cortex (similar to an eleptiform focus), sensory deprivation, and a misperception of what are internally (imagination) and externally generated sounds. All of these theories could ultimately be related to a pathophysiologic condition. A heightened emotional state may also contribute to the experience of AHs. It is reasonable to consider sophisticated audiological evaluations as a key element in helping define AHs because of the auditory nature of the hallucinations. Although audiological results are scattered, there do seem to be some indications that dichotic listening performance and auditory evoked potentials may be useful in learning about AHs. Perhaps one of the biggest breakthroughs in learning about AHs has been functional imaging studies (e.g., MRI, PET). Clearly, certain auditory areas of the brain become activated when AHs begin or even shortly before they begin. Functional imaging studies have provided an anatomical basis for AHs and support the role of the central auditory system in AHs. Perhaps the most popular treatment for AHs is transcranial magnetic stimulation (TMS). Data are emerging that indicate this technique may develop into a dependable procedure. Counseling techniques, distraction approaches, and acoustic masking procedures have all shown some usefulness as a treatment for AHs. Although certain drugs (especially in high doses) can cause auditory hallucinations, medications can also help in their treatment. Ultimately, the most successful technique for treating AHs will probably be to remove the underlying cause - if it can be discovered.