Full-Duplex-Bench-v3: Benchmarking Tool Use for Full-Duplex Voice Agents Under Real-World Disfluency
Organizations: National Taiwan University · NVIDIA
Abstract
We introduce Full-Duplex-Bench-v3 (FDB-v3), a benchmark for evaluating spoken language models under naturalistic speech conditions and multi-step tool use. Unlike prior work, our dataset consists entirely of real human audio annotated for five disfluency categories, paired with scenarios requiring chained API calls across four task domains. We evaluate six model configurations -- GPT-Realtime, Gemini Live 2.5, Gemini Live 3.1, Grok, Ultravox v0.7, and a traditional Cascaded pipeline (WhisperGPT-4oTTS) -- across accuracy, latency, and turn-taking dimensions. GPT-Realtime leads on Pass@1 (0.600) and interruption avoidance (13.5%); Gemini Live 3.1 achieves the fastest latency (4.25s) but the lowest turn-take rate (78.0%); and the Cascaded baseline, despite a perfect turn-take rate, incurs the highest latency (10.12s). Across all systems, self-correction handling and multi-step reasoning under hard scenarios remain the most consistent failure modes.
Figures & tables
| Domain | Mock API Functions |
|---|---|
| Travel & Identity | search_flights(destination, date) |
| book_ticket(passenger_name, flight_id) | |
| update_travel_profile(document_type, document_number) | |
| Finance & Billing | query_card_benefits(card_last_4, category) |
| calculate_currency_exchange(amount, from_currency, to_currency) | |
| modify_autopay_source(new_account_id) |
| Tool Use | Turn-Taking Dynamics | |||||||
|---|---|---|---|---|---|---|---|---|
| Tool Sel | Arg Acc | Resp Qual | Pass@1 | Take-turn | Latency | Interrupt | Filler | |
| GPT-Realtime | 0.876 | 0.680 | 0.792 | 0.600 | 96.0% | 6.89s | 13.5% | 16.9% |
| Gemini Live 2.5 | 0.786 | 0.593 | 0.554 | 0.490 | 92.0% | 7.26s | 14.1% | 8.9% |
| Gemini Live 3.1 | 0.817 | 0.588 | 0.718 | 0.540 | 78.0% | 4.25s | 19.2% | 31.7% |
| Grok | 0.797 | 0.542 | 0.617 | 0.430 | 94.0% | 6.65s | 25.5% | 44.3% |
| Ultravox | 0.794 | 0.513 | 0.510 | 0.410 | 96.0% | 8.40s | 47.9% | 88.0% |
| Model | Filler | Pause | Hesitation | False Start | Self-Corr |
|---|---|---|---|---|---|
| GPT-Realtime | 0.621 | 0.556 | 0.700 | 0.667 | 0.588 |
| Gemini Live 2.5 | 0.621 | 0.444 | 0.600 | 0.417 | 0.471 |
| Gemini Live 3.1 | 0.586 | 0.500 | 0.600 | 0.583 | 0.353 |
| Grok | 0.483 | 0.333 | 0.500 | 0.583 | 0.294 |
| Ultravox | 0.414 | 0.333 | 0.500 | 0.250 | 0.353 |
| Cascaded | 0.448 | 0.444 | 0.600 | 0.500 | 0.176 |
| Model | Easy | Medium | Hard |
|---|---|---|---|
| GPT-Realtime | 0.750 | 0.588 | 0.433 |
| Gemini Live 2.5 | 0.667 | 0.500 | 0.267 |
| Gemini Live 3.1 | 0.694 | 0.588 | 0.300 |
| Grok | 0.583 | 0.471 | 0.200 |
| Ultravox | 0.556 | 0.382 | 0.267 |
| Cascaded | 0.639 | 0.441 | 0.233 |
| Model | Ecommerce | Finance | Housing | Travel |
|---|---|---|---|---|
| GPT-Realtime | 0.552 | 0.960 | 0.308 | 0.600 |
| Gemini Live 2.5 | 0.483 | 0.760 | 0.231 | 0.500 |
| Gemini Live 3.1 | 0.448 | 0.920 | 0.269 | 0.550 |
| Grok | 0.414 | 0.760 | 0.115 | 0.450 |
| Ultravox | 0.345 | 0.680 | 0.192 | 0.450 |
| Cascaded | 0.414 | 0.800 | 0.192 | 0.400 |
| Model | First Word | Tool Call | Task Compl. |
|---|---|---|---|
| GPT-Realtime | 6.36 | 3.89 | 6.89 |
| Gemini Live 2.5 | 7.03 | 4.61 | 7.26 |
| Gemini Live 3.1 | 3.95 | 2.21 | 4.25 |
| Grok | 5.97 | 0.63 | 6.65 |
| Ultravox | 3.88 | 6.01 | 8.40 |
| Cascaded | 8.78 | 3.15 | 10.12 |
| Model | Tool | Arg | Resp | 1 st Resp | Tool Call | Compl. |
|---|---|---|---|---|---|---|
| Sel | Acc | Qual | (s) | (s) | (s) | |
| GPT-RT | 1.00 | 1.00 | 1.00 | 8.48 | 6.40 | 9.20 |
| Gem 2.5 | 1.00 | 1.00 | 1.00 | 6.16 | 3.60 | 6.16 |
| Gem 3.1 | 1.00 | 1.00 | 1.00 | 3.36 | 2.43 | 3.92 |
| Grok | 1.00 | 1.00 | 1.00 | 5.20 | 2.39 | 5.92 |
| Ultravox | 1.00 | 0.67 | 0.00 | 2.64 | 6.31 | 8.16 |
| Model | Tool | Arg | Resp | 1 st Resp | Tool Call | Compl. |
|---|---|---|---|---|---|---|
| Sel | Acc | Qual | (s) | (s) | (s) | |
| GPT-RT | 1.00 | 1.00 | 1.00 | 4.40 | 2.55 | 4.40 |
| Gem 2.5 | 1.00 | 1.00 | 0.00 | 5.28 | 4.23 | 5.28 |
| Gem 3.1 | 1.00 | 0.00 | 0.00 | 2.56 | 2.27 | 2.56 |
| Grok | 0.50 | 0.00 | 1.00 | — | 2.47 | — |
| Ultravox | 1.00 | 1.00 | 0.00 | 1.36 | 0.18 | 3.04 |
Voice Agent Evaluation
Voice agent evaluation measures how reliably spoken AI systems understand, respond, take actions, and recover in real interactions.
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