Deepgram Flux English is ahead on time to first text and final-text delay, and GPT Realtime Whisper on the Pipecat Dataset and the Ocular Dataset.
Every model's error rate on the public clips, against how long its transcript takes to settle.
Word error rate on 1,000 clips from Pipecat's STT benchmark dataset.
GPT Realtime Whisper, 1.75 points lower
Word error rate on eight licensed recordings provided by Ocular.
GPT Realtime Whisper, 0.65 points lower
Median delay before the first words arrive, from the first audio packet.
Deepgram Flux English, 588ms sooner
Median delay after the speaker stops before the transcript is final.
Deepgram Flux English, 435ms sooner
Lower is better on every metric. The small figure is each model's place in the whole field.
Both measured on the same 206 streamed Ocular Dataset turns. P90 and P95 say what a caller meets on a bad turn, which a median hides.
| Measure | Model | P50 | P90 | P95 |
|---|---|---|---|---|
| Time to first text | Deepgram Flux English | 791ms | 1.23s | 1.51s |
| GPT Realtime Whisper | 1.38s | 1.84s | 2.86s | |
| Final-text delay | Deepgram Flux English | 108ms | 132ms | 141ms |
| GPT Realtime Whisper | 543ms | 647ms | 669ms |
Open on the metric where the two sit furthest apart, with the other three a tab away.
Word error rate on 1,000 clips from Pipecat's STT benchmark dataset. Lower is better.
| # | Model | Pipecat Dataset | clips | |
|---|---|---|---|---|
| 1 | AssemblyAI Universal 3.5 Pro | 1.93% | 1,000 | |
| 2 | Google Chirp 3 | 2.00% | 1,000 | |
| 3 | Reson8 | 2.10% | 1,000 | |
| 4 | GPT Realtime Whisper | 2.16% | 1,000 | |
| 5 | Cartesia Ink 2 | 2.39% | 1,000 | |
| 6 | Speechmatics Linden | 2.46% | 998 | |
| 7 | Google Chirp 2 | 2.59% | 1,000 | |
| 8 | Inworld STT-1 | 2.72% | 1,000 | |
| 9 | GPT-4o Mini Transcribe | 3.35% | 1,000 | |
| 10 | Deepgram Nova-3 | 3.46% | 1,000 | |
| 11 | Smallest Pulse | 3.66% | 1,000 | |
| 12 | GPT-4o Transcribe | 3.90% | 1,000 | |
| 13 | Deepgram Flux English | 3.90% | 999 | |
| 14 | Deepgram Flux Multilingual | 4.96% | 999 | |
| 15 | Gradium | 6.48% | 1,000 |
Counts are the clips each model returned usable text for, so they differ between models and between datasets.
Every model's error rate on the public clips, against the same model on real conversations.
How soon each model returns its first words, against how soon its transcript is final.
| Model | Pipecat clips | Ocular recordings | Turns timed | Failed |
|---|---|---|---|---|
| Deepgram Flux English | 999 | 8 | 199 | 7 |
| GPT Realtime Whisper | 1,000 | 8 | 206 | 0 |
A clip counts only where the model returned usable text, so counts differ between models. Word error rate is measured the same way throughout: incorrect, missing, and extra words against the reference transcript.
On the 1,000 public Pipecat clips, Deepgram Flux English scores 3.90% and GPT Realtime Whisper 2.16%, so GPT Realtime Whisper makes fewer errors by 1.75 points. On the eight licensed Ocular recordings, Deepgram Flux English scores 4.18% and GPT Realtime Whisper 3.53%, so GPT Realtime Whisper makes fewer errors by 0.65 points. Word error rate counts incorrect, missing, and extra words against the reference transcript, so lower is better.
Deepgram Flux English returns first text 588ms sooner, at 791ms against 1.38s at the median. Deepgram Flux English has the final transcript 435ms sooner, 108ms after the speaker stops against 543ms. Both are measured on the same 206 streamed turns.
Both ran the same two datasets under the same conditions as every other model in the benchmark: 1,000 public clips from Pipecat's STT benchmark dataset and eight licensed conversation recordings from Ocular. Deepgram Flux English returned usable text for 999 of the public clips and GPT Realtime Whisper for 1,000. Latency uses each provider's own supported finalization contract.