HeyGen Voice

HeyGen Voice 1 is an in-house text-to-speech and voice cloning model developed by HeyGen, built specifically to handle narration, localized media, and dynamic video voiceovers. Released in October 2026, the model focuses on maintaining natural pacing, phrasing, and timbre across 39 languages. Unlike conventional text-to-speech models, it is engineered to adapt its acoustic delivery to match different visual and scene environments.

The model supports both instant voice cloning from short 60-second audio samples and professional voice cloning using longer multi-minute training sessions. It features an expressiveness adjustment layer that allows users to modulate inflection and emotional dynamics without losing the original speaker's identity. Audio outputs are typically streamed in high-fidelity 44.1 kHz mono PCM or formatted into files like WAV and MP3.

When integrating HeyGen Voice 1 via API or studio settings, adjusting parameters such as similarity and expressiveness optimizes performance depending on the target use case. Higher expressiveness settings align with dynamic video contexts, whereas maximum similarity configurations preserve strict speaker likeness. Developers can utilize standard REST endpoints or server-sent events for streaming audio chunks with optional word-level timestamps.