The objective of this thesis is to empirically test the practical implications of the functional load (FL) principle in German. The findings informed the selection of German phonemic contrasts for perceptual training of L2 German learners in a follow-up study. Previous research has suggested that sound contrasts carrying a high FL play a central role in conveying meaning, which closely links to the notions of intelligibility and comprehensibility of spoken utterances. Recent attention to FL in second language (L2) English pronunciation pedagogy highlights its role in selecting appropriate L2 sounds to train. In Study 1, the FL hierarchy of German and the impact of high vs. low FL segments on intelligibility and comprehensibility is tested among L1 German listeners. Results show that high FL errors have a more detrimental effect than low FL errors, but two errors are more severe than one, regardless of FL classification. Study 2 explores two types (i.e., audio and audiovisual) of high-variability phonetic training (HVPT) for challenging German sound contrasts among beginner L2 learners. HVPT employs multiple talkers and variable phonetic environments, thereby enhancing discrimination of sound contrasts. Results showed that especially audiovisual HVPT led to reduced discrimination accuracy, suggesting a need to investigate its use for training beginner learners. These findings shed light upon FL’s applicability in conjunction with word recognition models, thereby guiding future work on FL in L2 pronunciation pedagogy. They also provide insights into the theoretical implications of the HVPT technique in fostering perceptual abilities among beginner L2 learners
