This communication concerns the contribution of acoustic cues to the perception of non-native accents and presents some solutions to help learners to master the acoustic cues of the foreign language. Elementary acoustic cues (F0 frequency, formants…) will be presented by using copy synthesis used to pilot the Klatt formant synthesizer. This enables their perceptual contribution and that of more complex acoustic cues, which play a major role in the identification of speech sounds, to be evaluated easily. The non-native accent is mainly due to the:—realization of incorrect tones, stress patterns, and more generally prosody,—use of the mother tongue phonemes instead of those of the second language,—use of inappropriate acoustic cues to realize a phonetic feature. This is often the case with the voiced/unvoiced feature which covers a range of acoustic cues. These deviations depend on the phonetic specificities of the mother tongue with respect to those of the second language. The first aspect of corrections is the automatic diagnosis of non-native deviations. Learners can be made aware of them, trained to learn new phonetic contrasts, or guided by providing them with appropriate articulatory information, or acoustic feedback which is particularly efficient for prosody.