Deepgram Nova-3 vs Soniox STT-RT v5
Soniox STT-RT v5 is ahead on the Pipecat Dataset and final-text delay, and Deepgram Nova-3 on time to first text. The Ocular Dataset is too close to call.
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
Pick Deepgram Nova-3 for showing words while the caller is still talking (131ms sooner). Pick Soniox STT-RT v5 for accuracy on clean, scripted audio (0.92 points lower) and quick turn-taking once the caller stops (65ms sooner). For accuracy on real phone conversations, the gap is inside the margin of error, so neither is ahead.
The four metrics, side by side
- Deepgram Nova-3
- 3.46%12th
- Soniox STT-RT v5
- 2.54%8th
Soniox STT-RT v5, 0.92 points lower
- Deepgram Nova-3
- 4.39%11th
- Soniox STT-RT v5
- 3.92%6th
Too close to call: inside the margin of error
- Deepgram Nova-3
- 1.06s7th
- Soniox STT-RT v5
- 1.20s9th
Deepgram Nova-3, 131ms sooner
- Deepgram Nova-3
- 103ms4th
- Soniox STT-RT v5
- 38ms1st
Soniox STT-RT v5, 65ms 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
Deepgram Nova-3 shows first text after 2.07s and final text after 155ms, 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 | Deepgram Nova-3 | 1.06s | 1.10s | 2.07s |
| Soniox STT-RT v5 | 1.20s | 1.67s | 1.71s | |
| Final-text delay | Deepgram Nova-3 | 103ms | 143ms | 155ms |
| 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.
How each ranks among all 17 models
Place among the 17 models on each metric. Lower is better on all four.
| Metric | Nova-3 | STT-RT v5 |
|---|---|---|
| Pipecat Dataset WER | 3.46%12th of 17 | 2.54%8th of 17 |
| Ocular Dataset WER | 4.39%11th of 17 | 3.92%6th of 17 |
| Time to first text | 1.06s7th of 15 | 1.20s9th of 15 |
| Final-text delay | 103ms4th of 17 | 38ms1st of 17 |
How much audio each model was tested on
| Model | Pipecat clips | Ocular recordings | Turns timed | Failed |
|---|---|---|---|---|
| Deepgram Nova-3 | 1,000 | 8 | 202 | 0 |
| 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
- Deepgram Nova-3 vs GPT-4o Mini Transcribe
- Deepgram Nova-3 vs Smallest Pulse
- Deepgram Nova-3 vs GPT-4o Transcribe
- Deepgram Nova-3 vs Deepgram Flux English
- Deepgram Nova-3 vs Inworld STT-1
- Deepgram Nova-3 vs Speechmatics Linden
- Deepgram Nova-3 vs Cartesia Ink 2
- Deepgram Nova-3 vs GPT Realtime Whisper
- Deepgram Nova-3 vs Reson8
- Deepgram Nova-3 vs Google Chirp 3
- Deepgram Nova-3 vs Deepgram Flux Multilingual
- Deepgram Nova-3 vs AssemblyAI Universal 3.6 Pro
- Deepgram Nova-3 vs Gradium
- 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 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, Deepgram Nova-3 or Soniox STT-RT v5?
Soniox STT-RT v5 is more accurate on the public clips. On the 1,000 public Pipecat clips, Deepgram Nova-3 scores 3.46% and Soniox STT-RT v5 2.54%, so Soniox STT-RT v5 makes fewer errors by 0.92 points. On the eight licensed Ocular recordings, Deepgram Nova-3 scores 4.39% and Soniox STT-RT v5 3.92%, with likely ranges of 3.42 to 5.25% 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 Deepgram Nova-3 faster than Soniox STT-RT v5?
No. Soniox STT-RT v5 finishes the transcript 65ms sooner. Deepgram Nova-3 has the final transcript 103ms after the speaker stops and Soniox STT-RT v5 38ms, at the median. Both are measured on the same 206 streamed turns.
Is Deepgram Nova-3 or Soniox STT-RT v5 better for voice agents?
Soniox STT-RT v5 finishes the transcript 65ms 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 Deepgram Nova-3 and Soniox STT-RT v5 stream text while the speaker is talking?
Yes, both return partial text before the speaker stops. Deepgram Nova-3 shows first text after 1.06s and Soniox STT-RT v5 after 1.20s, at the median, so Deepgram Nova-3 is 131ms sooner.