Tinnitus ("acúfenos" in spanish) is a sound or noise perceived in the ears in absence of external sound stimulation. It can be present in a single ear, in both, or in the head.

As hyperacusis, tinnitus is not considered a disease, but a symptom of an underlying problem.

Since tinnitus is generated in the head, it can arise due to mechanical causes (e.g. a dysfunction in the temporomandibular joint or repetitive muscular contractions near the ears) which may produce a constant movement in the eardrum, and by this also sounds. This type of tinnitus is called "objective tinnitus".

In the other hand, when its origin is in the auditory system, tinnitus is called "subjective tinnitus".