An adaptation level theory of tinnitus audibility

Abstract

Models of tinnitus suggest roles for auditory, attention, and emotional networks in tinnitus perception. A model of tinnitus audibility based on Helson's (1964) adaptation level theory (ALT) is hypothesized to explain the relationship between tinnitus audibility, personality, memory, and attention. This theory attempts to describe how tinnitus audibility or detectability might change with experience and context. The basis of ALT and potential role of auditory scene analysis in tinnitus perception are discussed. The proposed psychoacoustic model lends itself to incorporation into existing neurophysiological models of tinnitus perception. It is hoped that the ALT hypothesis will allow for greater empirical investigation of factors influencing tinnitus perception, such as attention and tinnitus sound therapies.

Keywords: adaptation level; model; tinnitus; treatment.

Figure 1

(A) Theoretical relationship between orienting response (OR) to tinnitus in a background sound B as a function of different tinnitus adaptation levels (ALTIN1, ALTIN2, and ALTIN3; B < AL; based on Lauterbach, , Figure 2). The curves represent signal distribution. The OR is greater to the more audible tinnitus (OR ALTIN2). An increase in background sound level (horizontal arrow) should reduce orientation to the tinnitus (illustrated for one adaptation level, OR ALTIN2 reducing to ALTIN2, the direction of change is shown by the vertical arrow). (B) OR before (top curve) and after (bottom curve) attention training. Less focus on tinnitus should reduce the strength of OR to tinnitus (shown for ALTIN2).

Figure 2

Theoretical relationship illustrating adaptation effects on tinnitus audibility (based on Lauterbach, , Figure 1). “ALTIN” is the adaptation level (center of reference) at a point in time, B represents the level of background sound in the environment (B < AL), d is the difference between the adaptation level for tinnitus and background sound (contrast). The larger the d value (AL − B) the better the perceived audibility of tinnitus. (A) Normal level of tinnitus (ALTIN1) for an individual. (B) Adaptation level (ALTIN2) raised due to emotional events, stress, anxiety (ALT’s residual factor). (C) Adaptation level (ALTIN3) reduced due to management of residual factors through counseling or psychological therapy. (D) Same adaptation level (ALTIN3) with raised background sound level (representing sound therapy and counseling); tinnitus audibility d is reduced due the combined effect of a lower adaptation level and reduced contrast. The minimum masking level (MML) is illustrated as an upper theoretical limit to which sound may influence the adaptation level of tinnitus.