Gradium Launches Voice Design for Synthetic Voice Generation

Paris-based Gradium, a voice AI company that originated from the Kyutai research lab, has introduced Voice Design, a novel system capable of generating entirely new synthetic voices based on written descriptions. This technology addresses a common bottleneck for voice agent teams who often require specific vocal characteristics not present in existing voice catalogs. Traditionally, fulfilling such requests involved either finding a suitable voice from a limited selection or employing voice cloning, a process that necessitates sourcing audio, obtaining consent, and securing licensing for each individual speaker. Voice Design bypasses these complexities by accepting a textual description as its sole input, producing complete, ready-to-use voices in a matter of seconds without requiring any reference audio or speaker identification.

The Voice Design system is now accessible through the Gradium API and its Studio platform, integrated into all subscription tiers, including the free plan. The generated voices utilize the same streaming Text-to-Speech (TTS) endpoint as Gradium's catalog voices, maintaining consistent latency and output formats. The core of the system lies in its ability to interpret detailed casting briefs provided as text. Gradium's documentation outlines a comprehensive list of attributes the model responds to, encompassing elements such as gender, age range, accent or origin, pitch, speaking pace, energy level, vocal timbre and resonance, speech register, delivery mannerisms, and the specific role the voice is intended to perform. These descriptions can range from 1 to 500 characters and are supported in English, French, Spanish, Portuguese, and German. Gradium recommends concluding the prompt with the intended use case, as this information significantly influences the voice's delivery and register, going beyond mere tonal characteristics.

Upon submitting a prompt, Voice Design typically returns one to five candidate voices, which are variations of a single character, usually within 3 to 5 seconds. To generate a different character, a new, distinct description must be provided, rather than requesting additional samples of the same character. The process of moving from a candidate to a production-ready voice involves a sequence of four API calls. Initially, a POST request to `/voice-generator/generate` creates candidate IDs with a 'ready: false' status. Subsequently, a GET request to `/voice-generator/embeddings` is used to poll the system until the 'ready' status for these candidates is updated to 'true'. Each candidate voice can then be auditioned using the standard TTS endpoint by referencing its unique candidate ID as the `voice_id`. Finally, a POST request to `/voices/from-embedding` is used to promote the selected candidate voice for production use. A key distinction highlighted by Gradium is that these generated voices do not carry the same restrictions as cloned voices; for instance, audition text is not capped.