Learning the phonological system of a second language is a major challenge when significant phonetic and phonological differences exist between the native and target languages. For Persian speakers learning German, several vowels, consonants, and consonant clusters are often produced inaccurately because they are absent from or structurally different in the Persian phonological system. This study aims to design and explain an instructional–speech therapeutic protocol to improve the production of selected difficult German phonemes and consonant clusters among Persian learners.

The theoretical framework is based on research in second language phonological acquisition and speech therapy. Flege’s Speech Learning Model emphasizes the interaction between the phonological systems of the first and second languages in shaping phonetic perception and production. Research on phonological awareness shows that increasing learners’ perceptual sensitivity to phonetic contrasts can improve phoneme production. In addition, neurolinguistic studies indicate that structured and targeted practice can stabilize speech motor patterns through neuroplasticity. Combining perceptual training with productive practice is one of the most effective approaches to improving second language pronunciation.

This study identifies several German phonemes and consonant clusters that are typically difficult for Persian learners, including the front rounded vowels /yː/ and /øː/, the palatal fricative /ç/, and the clusters /ʃt/, /ʃp/, /pf/, and /ps/. A five‑stage instructional–therapeutic protocol was developed, consisting of assessment, perception training, isolated production, graded practice, and generalization. Exercises progress from syllables and words to phrases, sentences, and semi‑spontaneous speech, following principles such as hierarchical practice, immediate feedback, and gradual progression from simple to complex structures.