Google Chirp 2 vs Soniox STT-RT v5
Soniox STT-RT v5 is ahead of Google Chirp 2 on time to first text and final-text delay. The Pipecat Dataset and The Ocular Dataset are too close to call.
Google Chirp 2 has a newer release. See Google Chirp 3 vs Soniox STT-RT v5.
Last updated Methodology by Dileep Chagam
Accuracy vs speed
Each dot is one model. Bottom-left is best: fewer errors and a faster final transcript.
Which to pick
Soniox STT-RT v5 is the better pick over Google Chirp 2 on every measure that separates them: showing words while the caller is still talking (3.30s sooner) and quick turn-taking once the caller stops (530ms sooner). For accuracy on clean, scripted audio and accuracy on real phone conversations, the gap is inside the margin of error, so neither is ahead.
The four metrics, side by side
- Google Chirp 2
- 2.59%9th
- Soniox STT-RT v5
- 2.54%8th
Too close to call: inside the margin of error
- Google Chirp 2
- 3.80%5th
- Soniox STT-RT v5
- 3.92%6th
Too close to call: inside the margin of error
- Google Chirp 2
- 4.50s15th
- Soniox STT-RT v5
- 1.20s9th
Soniox STT-RT v5, 3.30s sooner
- Google Chirp 2
- 568ms15th
- Soniox STT-RT v5
- 38ms1st
Soniox STT-RT v5, 530ms sooner
Lower is better on every metric. The small figure is each model's place in the whole field. What each metric measures.
- WER · Word error rate
- Share of words the model got wrong: replaced, missing or added. Lower is better.
- Pipecat Dataset
- 1,000 short public clips from Pipecat's STT benchmark dataset.
- Ocular Dataset
- 8 recordings from 4 real phone conversations, licensed from Ocular.
- TTFT · Time to first text
- How long after the audio starts streaming until the first words appear.
- TTFS · Final-text delay
- How long after the caller stops until the full transcript arrives. A voice agent waits for this before it replies.
First text and final text, at three percentiles
Google Chirp 2 shows first text after 8.15s and final text after 1.22s, and Soniox STT-RT v5 shows first text after 1.71s and final text after 79ms, on a bad turn (P95) across the same streamed turns.
| Measure | Model | P50 | P90 | P95 |
|---|---|---|---|---|
| Time to first text | Google Chirp 2 | 4.50s | 6.40s | 8.15s |
| Soniox STT-RT v5 | 1.20s | 1.67s | 1.71s | |
| Final-text delay | Google Chirp 2 | 568ms* | 1.04s* | 1.22s* |
| Soniox STT-RT v5 | 38ms | 72ms | 79ms |
- P50 / P90 / P95 · Typical, slow and slowest turns
- Half of turns are faster than P50. Only 1 in 10 is slower than P90, and 1 in 20 slower than P95.
* Final-text delay is the observed time after stream close, because controlled finalization is not available for this model. Compare it with care against models that finalize on request.
How each ranks among all 17 models
Place among the 17 models on each metric. Lower is better on all four.
| Metric | Chirp 2 | STT-RT v5 |
|---|---|---|
| Pipecat Dataset WER | 2.59%9th of 17 | 2.54%8th of 17 |
| Ocular Dataset WER | 3.80%5th of 17 | 3.92%6th of 17 |
| Time to first text | 4.50s15th of 15 | 1.20s9th of 15 |
| Final-text delay | 568ms15th of 17 | 38ms1st of 17 |
How much audio each model was tested on
| Model | Pipecat clips | Ocular recordings | Turns timed | Failed |
|---|---|---|---|---|
| Google Chirp 2 | 1,000 | 8 | 205 | 1 |
| Soniox STT-RT v5 | 1,000 | 8 | 200 | 6 |
Only clips with usable text count, so the two totals can differ. How WER is scored.
Related comparisons
- Google Chirp 2 vs Google Chirp 3
- Soniox STT-RT v5 vs Speechmatics Linden
- Soniox STT-RT v5 vs Cartesia Ink 2
- Soniox STT-RT v5 vs Inworld STT-1
- Soniox STT-RT v5 vs GPT Realtime Whisper
- Soniox STT-RT v5 vs Reson8
- Soniox STT-RT v5 vs Google Chirp 3
- Soniox STT-RT v5 vs AssemblyAI Universal 3.6 Pro
- Soniox STT-RT v5 vs GPT-4o Mini Transcribe
- Soniox STT-RT v5 vs Deepgram Nova-3
- Soniox STT-RT v5 vs Smallest Pulse
- Soniox STT-RT v5 vs GPT-4o Transcribe
- Soniox STT-RT v5 vs Deepgram Flux English
- Soniox STT-RT v5 vs Deepgram Flux Multilingual
- Soniox STT-RT v5 vs Gradium
Frequently asked questions
Which is more accurate, Google Chirp 2 or Soniox STT-RT v5?
Google Chirp 2 and Soniox STT-RT v5 are too close to call on accuracy. On the 1,000 public Pipecat clips, Google Chirp 2 scores 2.59% and Soniox STT-RT v5 2.54%, with likely ranges of 2.31 to 2.89% and 2.27 to 2.83%. The ranges overlap, so the difference is too close to call. On the eight licensed Ocular recordings, Google Chirp 2 scores 3.80% and Soniox STT-RT v5 3.92%, with likely ranges of 2.93 to 4.60% and 2.60 to 4.86%. The ranges overlap, so the difference is too close to call. Word error rate counts incorrect, missing, and extra words, so lower is better.
Is Google Chirp 2 faster than Soniox STT-RT v5?
No. Soniox STT-RT v5 finishes the transcript 530ms sooner. Google Chirp 2 has the final transcript 568ms after the speaker stops and Soniox STT-RT v5 38ms, at the median. Both are measured on the same 206 streamed turns.
Is Google Chirp 2 or Soniox STT-RT v5 better for voice agents?
Soniox STT-RT v5 finishes the transcript 530ms sooner, and the two are too close to call on real conversations. A voice agent cannot reply until the final transcript arrives, and the Ocular recordings are real conversations.
Do Google Chirp 2 and Soniox STT-RT v5 stream text while the speaker is talking?
Yes, both return partial text before the speaker stops. Google Chirp 2 shows first text after 4.50s and Soniox STT-RT v5 after 1.20s, at the median, so Soniox STT-RT v5 is 3.30s sooner.