FAC-FACodec: Controllable Zero-Shot Foreign Accent Conversion with Factorized Speech Codec

Abstract: Previous accent conversion (AC) methods, including foreign accent conversion (FAC), lack explicit control over the degree of modification. Because accent modification can alter the perceived speaker identity, balancing conversion strength and identity preservation is crucial. We present an AC framework that provides an explicit, user-controllable parameter for accent modification. The method targets pronunciation while preserving suprasegmental cues such as intonation and phoneme durations. Results show performance comparable to recent AC systems, stronger preservation of speaker identity, and unique support for controllable accent conversion.