Figure 4.

Relative similarity of contact calls produced by two birds to their respective templates before, during and after injections with the ototoxic drug kanamycin. Each bird’s call similarities during and after injections are plotted relative to its average preinjection similarity score which was normalized to 1. Kanamycin causes a decrease in the precision of vocal production in both birds but this precision recovers within 5–15 days following the cessation of injections and well before the return of auditory function as defined by absolute thresholds, difference limens, call discrimination, and call recognition.