Deepgram Flux English is ahead of GPT-4o Transcribe on the Ocular Dataset and final-text delay. The two tie on the Pipecat 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.
Level
Word error rate on eight licensed recordings provided by Ocular.
Deepgram Flux English, 8.27 points lower
Median delay before the first words arrive, from the first audio packet.
Not comparable
Median delay after the speaker stops before the transcript is final.
Deepgram Flux English, 544ms 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-4o Transcribe | No text until the speaker stops | |||
| Final-text delay | Deepgram Flux English | 108ms | 132ms | 141ms |
| GPT-4o Transcribe | 652ms | 1.73s | 1.97s | |
Open on the metric where the two sit furthest apart, with the other three a tab away.
Final-text delay after the speaker stops. Lower is better.
| # | Model | Final text | turns | |
|---|---|---|---|---|
| 1 | Inworld STT-1 | 41ms | 206 | |
| 2 | Deepgram Nova-3 | 103ms | 202 | |
| 3 | Deepgram Flux English | 108ms | 199 | |
| 4 | Deepgram Flux Multilingual | 114ms | 175 | |
| 5 | Cartesia Ink 2 | 123ms | 198 | |
| 6 | Speechmatics Linden | 147ms | 194 | |
| 7 | AssemblyAI Universal 3.5 Pro | 180ms | 205 | |
| 8 | Smallest Pulse | 201ms | 206 | |
| 9 | Gradium | 212ms | 198 | |
| 10 | Reson8 | 235ms | 201 | |
| 11 | Google Chirp 3 | 475ms | 206 | |
| 12 | GPT Realtime Whisper | 543ms | 206 | |
| 13 | Google Chirp 2 | 568ms | 205 | |
| 14 | GPT-4o Mini Transcribe | 630ms | 206 | |
| 15 | GPT-4o Transcribe | 652ms | 206 |
Median across the same 206 Ocular Dataset turns. Providers finalize differently, so compare models with similar finalization contracts before treating small gaps as meaningful.
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-4o Transcribe | 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-4o Transcribe 3.90%, which is a tie. On the eight licensed Ocular recordings, Deepgram Flux English scores 4.18% and GPT-4o Transcribe 12.45%, so Deepgram Flux English makes fewer errors by 8.27 points. Word error rate counts incorrect, missing, and extra words against the reference transcript, so lower is better.
GPT-4o Transcribe returns no text while the speaker is talking, so time to first text cannot be compared. Deepgram Flux English has the final transcript 544ms sooner, 108ms after the speaker stops against 652ms. 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-4o Transcribe for 1,000. Latency uses each provider's own supported finalization contract.