Introduction

Tinnitus (from the Latin tinnire, which means to ring or to tinkle) describes the sensation of any sound perceived in the head or in the ears without an evident external stimulus. Though tinnitus is subjective, for clinical purposes it is subdivided into subjective and objective tinnitus, the latter describing those few incidents in which the sound is detected or potentially detectable by another observer. Tinnitus is a manifestation of malfunction in the processing of auditory signals involving both perceptual and psychological components and should as such be differentiated from auditory hallucinations, which are generally considered to be a symptom of psychiatric or neurological disorders.

The characteristics used to classify tinnitus depend on the purpose of the classification (box).1 Furthermore, distinctions should be made between acute and chronic tinnitus and between chronic tinnitus occurring after an acute tinnitus and chronic tinnitus of insidious onset.2 Tinnitus is considered to be chronic when is has been present for more than three months without signs of spontaneously resolving.

Prevalence

Most people experience tinnitus occasionally, and most experience it in silent soundproofed rooms. The British national study of hearing found that 10% of adults had prolonged spontaneous tinnitus—that is, tinnitus “usually lasting for longer than 5 minutes”; 1% experienced severe annoyance due to tinnitus, and in 0.5% of adults tinnitus severely reduced the ability to lead a normal life. The same study ascertained that 7% of the population in the United Kingdom present to their general practitioners with tinnitus and 2.4% are referred to hospitals.3 A largescale Swedish study4 reported somewhat higher figures: for 2.4% of adults “tinnitus plagues me all day,” and 14.2% suffered …