Evaluation of the Oldenburg sentence test in quiet to assess speech understanding during the initial fitting phase after Cochlear Implantation

In order to assess speech understanding and to measure the rehabilitation success through hearing systems, a variety of speech audiometric tests are used. The Freiburg monosyllable test (FBE, Hahlbrock, 1953) is the most commonly used German speech test in quiet for hearing diagnostics, hearing device prescriptions and fitting. Unfortunately, it provides a very limited number of test lists that are easily memorized by the patient. In addition, it is very difficult for CI users to understand isolated monosyllabic words, especially in the initial CI fitting phase. Another speech test that is often used in later CI fitting phases is the Oldenburg sentence test (OLSA, Wagener et al., 1999). The test lists of OLSA can be repeated any number of times due to their matrix structure. In this longitudinal study, FBE and OLSA were measured in quiet at four different points in time during the initial CI fitting phase. Namely, one week after the first activation of the speech processor (FA), two weeks, one month, and three months after FA. In both tests, the stimuli were presented to the CI-ear via loudspeakers at 65 dB SPL in free field. A masking noise was presented to the contra-lateral ear. As expected, the results show statistically significant improvements in speech intelligibility (p<0.005) for both tests between the measurement time points one week to one month after initial CI fitting and one week to three months after initial CI fitting. In addition, there is a high correlation between the results of the FBE and OLSA (r=0.88, p<0.001). The OLSA appears to be a suitable alternative to the FBE. The OLSA could be particularly advantageous for patients who have been fitted with hearing aids for many years as, unlike the FBE, less long-term learning effect is to be expected.