AssemblyAI Universal 3.5 Pro vs Reson8
AssemblyAI Universal 3.5 Pro is ahead of Reson8 on time to first text and final-text delay. The Pipecat Dataset and The Ocular Dataset are too close to call.
AssemblyAI Universal 3.5 Pro has a newer release. See AssemblyAI Universal 3.6 Pro vs Reson8.
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
AssemblyAI Universal 3.5 Pro is the better pick over Reson8 on every measure that separates them: showing words while the caller is still talking (1.91s sooner) and quick turn-taking once the caller stops (55ms 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
- AssemblyAI Universal 3.5 Pro
- 1.93%2nd
- Reson8
- 2.10%4th
Too close to call: inside the margin of error
- AssemblyAI Universal 3.5 Pro
- 4.23%10th
- Reson8
- 2.93%1st
Too close to call: inside the margin of error
- AssemblyAI Universal 3.5 Pro
- 489ms2nd
- Reson8
- 2.40s13th
AssemblyAI Universal 3.5 Pro, 1.91s sooner
- AssemblyAI Universal 3.5 Pro
- 180ms9th
- Reson8
- 235ms12th
AssemblyAI Universal 3.5 Pro, 55ms 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
AssemblyAI Universal 3.5 Pro shows first text after 1.08s and final text after 692ms, and Reson8 shows first text after 10.20s and final text after 398ms, on a bad turn (P95) across the same streamed turns.
| Measure | Model | P50 | P90 | P95 |
|---|---|---|---|---|
| Time to first text | AssemblyAI Universal 3.5 Pro | 489ms | 966ms | 1.08s |
| Reson8 | 2.40s | 7.97s | 10.20s | |
| Final-text delay | AssemblyAI Universal 3.5 Pro | 180ms | 532ms | 692ms |
| Reson8 | 235ms | 357ms | 398ms |
- 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 | Universal 3.5 Pro | Reson8 |
|---|---|---|
| Pipecat Dataset WER | 1.93%2nd of 17 | 2.10%4th of 17 |
| Ocular Dataset WER | 4.23%10th of 17 | 2.93%1st of 17 |
| Time to first text | 489ms2nd of 15 | 2.40s13th of 15 |
| Final-text delay | 180ms9th of 17 | 235ms12th of 17 |
How much audio each model was tested on
| Model | Pipecat clips | Ocular recordings | Turns timed | Failed |
|---|---|---|---|---|
| AssemblyAI Universal 3.5 Pro | 1,000 | 8 | 205 | 1 |
| Reson8 | 1,000 | 8 | 201 | 0 |
Only clips with usable text count, so the two totals can differ. How WER is scored.
Related comparisons
- AssemblyAI Universal 3.5 Pro vs AssemblyAI Universal 3.6 Pro
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- Reson8 vs AssemblyAI Universal 3.6 Pro
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- Reson8 vs GPT-4o Mini Transcribe
- Reson8 vs Deepgram Nova-3
- Reson8 vs Smallest Pulse
- Reson8 vs GPT-4o Transcribe
- Reson8 vs Deepgram Flux English
- Reson8 vs Deepgram Flux Multilingual
- Reson8 vs Gradium
Frequently asked questions
Which is more accurate, AssemblyAI Universal 3.5 Pro or Reson8?
AssemblyAI Universal 3.5 Pro and Reson8 are too close to call on accuracy. On the 1,000 public Pipecat clips, AssemblyAI Universal 3.5 Pro scores 1.93% and Reson8 2.10%, with likely ranges of 1.69 to 2.18% and 1.86 to 2.35%. The ranges overlap, so the difference is too close to call. On the eight licensed Ocular recordings, AssemblyAI Universal 3.5 Pro scores 4.23% and Reson8 2.93%, with likely ranges of 3.57 to 4.68% and 2.29 to 3.68%. 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 AssemblyAI Universal 3.5 Pro faster than Reson8?
Yes. AssemblyAI Universal 3.5 Pro finishes the transcript 55ms sooner. AssemblyAI Universal 3.5 Pro has the final transcript 180ms after the speaker stops and Reson8 235ms, at the median. Both are measured on the same 206 streamed turns.
Is AssemblyAI Universal 3.5 Pro or Reson8 better for voice agents?
AssemblyAI Universal 3.5 Pro finishes the transcript 55ms 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 AssemblyAI Universal 3.5 Pro and Reson8 stream text while the speaker is talking?
Yes, both return partial text before the speaker stops. AssemblyAI Universal 3.5 Pro shows first text after 489ms and Reson8 after 2.40s, at the median, so AssemblyAI Universal 3.5 Pro is 1.91s sooner.