Background Questionnaires, e.g. the APHAB, and speech-audiometry are the most used elements in measuring the success of hearing aid fitting (HAF). This study investigates the correlations between the results of the Freiburg monosyllabic word test without and with noise (FBE, FBE-S) and the results of the APHAB before and after HAF. Methods Data of the FBE, the FBE-S, and the APHAB, generated within HAF of 156 subjects were analyzed. After exclusion of a normal distribution of the data, Spearman's correlation and Cohen's effect size were determined. Results 73 of the 156 subjects (46.8%) were females, and 83 (53.2%) males. No significant correlation could be found between the EC-, the RV-, and the cumulative ECBNRV-subscale and the benefit of HAF in the FBE and FBE-S (EC: ease of communication, BN: background noise, RV: reverberation). Most of the remaining coefficients of correlation had a weak positive effect size. A middle positive effect size could only be demonstrated for 6 combinations, for the EC-subscale mostly. Conclusion The not strong effect sizes could assume that the results in speech-audiometry and the APHAB are not independent and complementing each other as parameters of hearing loss and benefit in HAF. The effect size could be explained by individually different possibilities for the compensation of hearing loss.