Possible Joint Involvement of the Cochlea and Semicircular Canals in the Perception of Low-Frequency Tinnitus, Also Called "The Hum" or "Taos Hum".

INTRODUCTION: "The hum" or "Taos hum" are common terms of a tinnitus with three remarkable features.

OBJECTIVE: A possible common background is reevaluated for the three features of the hum: being sensitive on sound, head rotation, and long-distance air travel.

MATERIALS AND METHODS: Questionnaires that were originally developed by Frosch were recalculated concerning the question of hum interactions with sounds. The question was split into the two affirmative answers a) "masking", which corresponds to the overrule of the hum by a sound, and b) "beats", which correspond to a nonlinear interaction with the hum as a Van der Pol-like oscillator.

RESULTS AND CONCLUSIONS: When interacting with sounds as beats the hum resulted in completely different dependencies with the other two features than when masked by sounds. The simultaneous features of the hum to generate beats and to be removed during head rotation are strongly dependent at an error below 0.1%. The simultaneous features to mask the hum with sounds and to experience a time-lag of its reappearance after long-distance air travel are dependent at an error below 1%. These two pairs of features have no overlapping dependencies. The term hum can be expected to be a collective term for at least two independent manifestations.