Speech Recognition Firm Soniox Releases STT v6 with Agent Text Input and Echo Filtering
Soniox launches STT v6, which uses the voice agent's outgoing text to improve short-reply accuracy and filter its own audio, though no independent benchmarks are yet available.
US-based speech recognition company Soniox released Soniox STT v6 on November 3, 2026. This latest generation of its speech-to-text API is designed specifically for voice agents, introducing two key innovations: "Agent Text Input" and "Agent Voice Echo Cancellation."
In traditional cascaded voice agent architectures, the STT model typically hears only the user's audio, lacking context about what the agent just said. This often leads to errors in recognizing short, context-dependent replies like names or numbers. Soniox STT v6 allows developers to stream the agent's outgoing text directly into the STT model, giving it awareness of both sides of the conversation to more accurately transcribe user responses.
Additionally, v6 uses this text context to distinguish between the agent's playback and the user's speech, automatically filtering out leaked agent audio. This mechanism aims to prevent voice agents from interrupting themselves when they hear their own output. However, Soniox documentation notes that this feature does not replace traditional Acoustic Echo Cancellation (AEC) but rather handles residuals left behind by AEC, recommending that both be used together.
Pricing for Soniox STT v6 is approximately $0.12 per hour for real-time streaming and $0.10 per hour for asynchronous file transcription, with speaker diarization and language identification included. The previous v5 models will be deprecated on December 15, 2026.
It is important to note that while Soniox claims v6 is "significantly" more accurate than v5, no independent third-party benchmark results have been published yet. The company's website still displays v5 data from the open-source Pipecat STT benchmark (1.34% semantic WER), leaving v6's actual performance pending developer validation.