Figure 3:

Posterior mean probability function (A) for one ear is computed using 5 sampled points. Red diamonds indicate the tone was inaudible; black pluses, audible. Acquisition function (B) is computed and identifies the point of maximum uncertainty between models (pink star). This point where models differ most is then queried for participant audibility (C, pink arrow). The participant detected this tone, so the updated set of points is used to recompute the posterior probabilities with a lower threshold near the frequency of that tone. After 40 sampled points, the updated posterior probability (D) has greatly reduced the uncertainty in the acquisition function (E) to the area we consider threshold. As such, the posterior probabilities after 40 (D) and 41 (F) samples are almost identical due to the small amount of uncertainty. Each tone response therefore updates the entire audiogram estimate across all frequencies, though much less as the test progresses.