DuplexSpeechBench-Document Grounding: Benchmarking Document Grounding and Hallucinations in Voice Agents
Organizations: Adobe Research, San Jose, USA · University of Maryland College Park, USA
Abstract
Voice agents enable low-latency, natural interaction, yet their ability to faithfully ground responses in external documents remains underexplored. We introduce DuplexSpeechBench-Document Grounding (DSB-DG), a benchmark for evaluating document grounding in voice agents across five professional domains. DSB-DG targets three failure modes: Context Saturation, which measures grounding under increasing document length; Grounding Decay, which measures retention of document facts across multi-turn dialogue; and Proactive Grounding, which evaluates whether context re-injection mitigates conversational drift. The benchmark contains 1,636 adversarially verified QA pairs from 50 documents covering five professional domains, and supports fully automatic evaluation of grounding accuracy, hallucination, and response latency. Across systems spanning cascaded, proprietary full-duplex and real-time, and open-weight speech2speech architectures, we find substantial differences in effective grounding capacity. While cascaded pipeline (ASR-LLM-TTS) achieves the highest grounding accuracy, Gemini-Live and GPT-Realtime closely trail behind. Open-weight systems exhibit distinct failure modes, most notably an abrupt context-capacity collapse and multi-turn grounding decay. More broadly, grounding fidelity degrades with context and conversational load, and failures frequently manifest as unsupported generations rather than abstention. We show that contextual grounding as a key unresolved challenge for reliable full-duplex voice agents.
Figures & tables
| Benchmark | Full- | Real- | Long | Long- | Multi- | Document- | Halluc. | Latency |
| Duplex | Time | Document | Context | Turn | Factuality | Eval. | Eval. | |
| SpokenSQuAD ( Li et al., 2018 ) | ✗ | ✗ | ✗ | ✗ | ✗ | ✓ | ✗ | ✗ |
| LongBench ( Bai et al., 2024 ) | ✗ | ✗ | ✓ | ✓ | ✗ | ✓ | ✗ | ✗ |
| Full-Duplex-Bench ( Lin et al., 2025 ; Lin et al., 2026c ) | ✓ | ✓ | ✗ | ✗ | ✗ | ✗ | ✗ | ✓ |
| FD-Bench ( Peng et al., 2025 ) | ✓ | ✓ | ✗ | ✗ | ✗ | ✗ | ✗ | ✓ |
| Full-Duplex-Bench-v2 ( Lin et al., 2026b ) | ✓ | ✓ | ✗ | ✗ | ✓ | ✗ | ✗ | ✓ |
| Domain | # Docs | # QA | Avg. Qs / Doc | Document Characteristics |
|---|---|---|---|---|
| Clinical Trials | 10 | 391 | 39.1 | Structured protocols, eligibility criteria, clinical endpoints |
| Earnings Calls | 10 | 314 | 31.4 | Financial reporting, analyst Q&A, dense numerical content |
| FDA 510(k) | 10 | 292 | 29.2 | Regulatory filings, device specifications, standardized structure |
| Commercial Leases | 10 | 358 | 35.8 | Contract clauses, cross-references, legal reasoning |
| Municipal Minutes | 10 | 281 | 28.1 | Procedural narratives, motions, amendments, voting records |
| Total | 50 | 1,636 | 32.7 | Multi-turn spoken conversations (20) grounded in documents |
| Model | T1 ( 500) | T2 ( 1k) | T3 ( 2k) | T4 ( 4k) | T5 ( 8k) |
|---|---|---|---|---|---|
| Cascaded | 88.7 | 89.8 | 90.3 | 90.4 | 88.5 |
| Gemini-Live | 85.9 | 86.9 | 87.4 | 90.2 | 86.9 |
| GPT-Realtime | 88.0 | 86.6 | 87.7 | 88.2 | 85.8 |
| MiniCPM-o | 85.9 | 87.6 | 88.0 | 87.2 | 74.0 |
| UV-32B | 87.0 | 85.4 | 85.5 | 80.2 | 75.4 |
| SALMONN | 77.4 | 76.3 | 70.3 | 37.2 | 25.4 |
| Domain | Cascaded | GPT-RT | Gemini-L | MiniCPM-o | UV-32B | SALMONN |
|---|---|---|---|---|---|---|
| Clinical | 83.9 | 78.9 | 81.4 | 80.7 | 82.5 | 62.5 |
| Earnings | 93.8 | 89.4 | 88.2 | 91.9 | 91.9 | 70.8 |
| FDA 510(k) | 82.1 | 84.6 | 78.6 | 78.6 | 84.6 | 57.3 |
| Leases | 98.6 | 98.6 | 96.4 | 95.7 | 97.8 | 86.2 |
| Municipal | 96.1 | 93.3 | 95.0 | 96.1 | 95.0 | 78.2 |
| Model | GA A | GA B | GA | GDS |
|---|---|---|---|---|
| Gemini-Live | 86.7 | 85.1 | 90.1 | |
| Cascaded | 86.7 | 86.7 | 86.7 | 0.0 |
| GPT-Realtime | 86.7 | 85.0 | 87.0 | 0.3 |
| MiniCPM-o | 83.3 | 86.7 | 81.7 | 1.7 |
| UV-32B | 80.0 | 78.3 | 75.0 | |
| SALMONN | 76.7 | 65.0 | 72.1 | 4.6 |
| Grounding Accuracy (%) | Injection Benefit (%) | ||||
| Model | |||||
| No refresh | 1 refresh | Multiple | |||
| GPT-Realtime | 79.6 | 94.2 | 88.1 | 14.6 | 8.5 |
| Cascaded | 87.8 | 94.2 | 94.9 | 6.4 | 7.1 |
| Gemini-Live | 83.89 | 84.44 | 83.89 | 0.56 | 0.0 |
| MiniCPM-o | 90.6 | 89.4 | 89.4 | 1.1 | 1.1 |
| Model | p50 (ms) | mean (ms) | p95 (ms) | QAL (ms) |
|---|---|---|---|---|
| Cascaded | 1469 | 8118 | 61563 | 143 |
| GPT-Realtime | 1214 | 1311 | 1761 | 150 |
| Moshi | 229 | 251 | 737 | 228 |
| MiniCPM-o | 2317 | 4566 | 11975 | 278 |
| Gemini-Live | 6806 | 9410 | 6949 | 856 |
| SALMONN | 3763 | 7665 | 30349 | 1118 |
Appendix figures & tables16 assets
Supplementary material from the paper’s appendix.
Appendix
| Domain | # Docs | Source | Mean Tokens | Token Range |
|---|---|---|---|---|
| Clinical Trials | 10 | ClinicalTrials.gov | 2,528 | 1,244–8,038 |
| Earnings Calls | 10 | SEC EDGAR | 9,403 | 1,370–22,524 |
| FDA 510(k) | 10 | openFDA | 4,946 | 2,788–7,301 |
| Commercial Leases | 10 | Synthetic | 6,779 | 6,671–6,875 |
| Municipal Minutes | 10 | Legistar | 3,092 | 1,335–7,660 |
| Domain | Grounded | Unanswerable | Total |
|---|---|---|---|
| Clinical Trials | 331 | 60 | 391 |
| Earnings Calls | 254 | 60 | 314 |
| FDA 510(k) | 233 | 59 | 292 |
| Commercial Leases | 302 | 56 | 358 |
| Municipal Minutes | 221 | 60 | 281 |
| Total | 1,341 | 295 | 1,636 |
| Domain | Type | Question | Reference Answer |
|---|---|---|---|
| Clinical Trials | grounded / direct_lookup | How many participants were enrolled in this study? | 20 participants |
| Earnings Calls | grounded / direct_lookup | What were Southern Company’s operating revenues for the fourth quarter of 2025? | $7.0 billion |
| FDA 510(k) | grounded / direct_lookup | What is the regulation number associated with the Francisella tularensis Real-time PCR Assay? | 21 CFR 866.4000 |
| Commercial Leases | grounded / multi_span | Who are the landlord and tenant in this lease agreement? | Landlord: Greenfield Realty Partners, LP; Tenant: David Martin |
| Municipal Minutes | grounded / direct_lookup | Who made the motion to approve the February 2025 meeting minutes? | Alderman James Rodriguez |
| Domain | Candidate Question | Decision | Reason |
|---|---|---|---|
| FDA 510(k) | What is the intended use of FMD Peripheral Guidewires? | Rejected | Insufficient document evidence |
| FDA 510(k) | Who is the regulatory contact for submissions related to the FMD Peripheral Guide Wire devices? | Rejected | Multiple plausible answers |
| FDA 510(k) | What is the exact submission date of the 510(k) premarket notification? | Rejected | “Unanswerable” but actually answerable |
| Earnings | What were Southern Company’s operating revenues for the fourth quarter of 2025? | Retained | Unique answer explicitly supported by context |
| Field | Operational Definition |
|---|---|
| Factual Accuracy | Binary judgment indicating whether the response is factually supported by the supplied document. |
| Hallucination Type | None ; Intrinsic , when the response contradicts information explicitly stated in the document; or Extrinsic , when the response introduces unsupported information not contained in the document. |
| No Response | The model fails to produce a scoreable answer, including silence or non-answer conversational behavior. |
| False Refusal | The model refuses to answer despite the required information being explicitly available in the supplied context. |
| Partial Credit | Integer partial_credit : = fully correct; = partially correct (captures the main point but misses a detail or hedges unnecessarily); = wrong, or refused when the question is answerable. For multi_span items a floor of is enforced when the response addresses the question and the judge’s explanation indicates at least one span was correct. |
| Question Addressed | Whether the response substantively attempts to answer the user’s question. |
| System | Checkpoint | Backbone | Context Interface | Precision | Hardware/API |
|---|---|---|---|---|---|
| Cascaded | whisper-1 / gpt-4o-2024-11-20 / tts-1 | GPT-4o | System prompt | – | hosted OpenAI API |
| GPT-Realtime | gpt-realtime-2025-08-28 | Not Public | System item | – | hosted OpenAI Realtime API |
| MiniCPM-o | openbmb/MiniCPM-o-4_5 | MiniCPM-o 4.5 | System prompt | bf16 | 1 A100-80GB ( 35 GB) |
| SALMONN | tsinghua-ee/SALMONN-7B | Vicuna-7B-v1.5 | System prompt | fp16 | 1 A100-80GB ( 27 GB) |
| UV-32B | fixie-ai/ultravox-v0_6-qwen-3-32b | Qwen3-32B | System prompt | bf16 | 1 A100-80GB ( 62 GB) |
| Moshi | kyutai/moshiko-pytorch-bf16 | Moshi/Helium-7B LM + Mimi | KV-cache prefill | bf16 | 1 A100-80GB ( 46 GB) |
| System | Temperature | Top- | Max Output | Seed |
|---|---|---|---|---|
| Cascaded | 0.1 | default | 300 | – |
| GPT-Realtime | 0.6 | N/A | provider default | – |
| MiniCPM-o | greedy | – | 256 | – |
| SALMONN | 1.0 | 0.9 | 150 (max_length) | – |
| UV-32B | greedy | – | 2048 | – |
| Moshi | not exposed | not exposed | N/A | – |
| Turn(s) | Content |
|---|---|
| 2–4 | Early document probes ( ) |
| 5–6 | Domain-relevant distractors |
| 7–9 | Intermediate probes ( ) |
| 10–12 | Domain-relevant distractors |
| 13–15 | Repeated probes ( ) |
| Turn | Type | User Utterance |
|---|---|---|
| 2 | Probe | What is the primary purpose of the study? |
| 4 | Probe | What imaging technique is considered the gold standard in this study? |
| 6 | Distractor | Do you think telemedicine is going to completely replace in-person visits someday? |
| 7 | Probe | What is the significance of an AUC value of 0.5? |
| 11 | Distractor | What are your thoughts on alternative medicine? Do you think it can really work alongside clinical treatments? |
| 13 | Probe | What are the key takeaways from the study? |
| Condition | Initial Context | Refresh Turn(s) |
|---|---|---|
| T3 document (at start) | None | |
| T3 document (at start) | one, before the late ( ) probe group | |
| T3 document (at start) | two, before the mid ( ) and late ( ) probe groups |
| Model | T1 | T2 | T3 | T4 | T5 |
|---|---|---|---|---|---|
| Cascaded | 12.2 | 10.6 | 9.5 | 9.5 | 12.3 |
| GPT-Realtime | 11.4 | 14.2 | 11.8 | 12.1 | 14.8 |
| Gemini-Live | 13.3 | 13.4 | 12.7 | 10.5 | 13.7 |
| MiniCPM-o | 13.9 | 12.7 | 12.3 | 13.1 | 25.0 |
| UV-32B | 13.0 | 11.6 | 11.4 | 10.5 | 12.7 |
| SALMONN | 22.6 | 24.4 | 30.1 | 29.8 | 36.5 |
| Model | HR | Intr. | Extr. |
|---|---|---|---|
| Cascaded | 10.8 | 8.2 | 2.5 |
| MiniCPM-o | 16.7 | 12.6 | 4.0 |
| GPT-Realtime | 13.1 | 11.4 | 1.7 |
| Gemini-Live | 12.6 | 10.0 | 2.6 |
| UV-32B | 11.6 | 10.0 | 1.6 |
| SALMONN | 29.5 | 27.7 | 1.8 |
| Model | NRR (%) | FCR (%) |
|---|---|---|
| GPT-Realtime | 86.6 | 12.3 |
| Gemini-Live | 85.6 | 13.2 |
| Cascaded | 84.6 | 14.2 |
| UV-32B | 80.3 | 19.0 |
| MiniCPM-o | 77.2 | 21.2 |
| SALMONN | 61.7 | 31.4 |
| Difficulty | Evidence position | |||||
|---|---|---|---|---|---|---|
| Model | Easy | Med. | Hard | Early | Mid | Late |
| Cascaded | 91.1 | 87.4 | 81.9 | 89.5 | 85.5 | 91.2 |
| GPT-Realtime | 89.7 | 86.7 | 68.1 | 84.2 | 87.0 | 88.6 |
| Gemini-Live | 87.6 | 89.1 | 82.6 | 83.4 | 88.0 | 90.4 |
| MiniCPM-o | 86.3 | 80.4 | 73.5 | 85.0 | 80.7 | 84.3 |
| UV-32B | 81.5 | 76.4 | 72.7 | 79.1 | 73.0 | 83.2 |
| Model | Median | Mean | p95 |
|---|---|---|---|
| Cascaded | 14 | 17.1 | 43 |
| GPT-Realtime | 18 | 18.7 | 33 |
| Gemini-Live | 13 | 14.4 | 30 |
| MiniCPM-o | 14 | 28.4 | 75 |
| UV-32B | 14 | 17.5 | 43 |
| SALMONN | 15 | 24.5 | 94 |
| Model | Tier | p50 (ms) | Mean (ms) | p95 (ms) |
|---|---|---|---|---|
| Moshi | T1 | 229 | 241 | 768 |
| Moshi | T2 | 229 | 254 | 781 |
| Moshi | T3 | 229 | 267 | 895 |
| Moshi | T4 | 229 | 236 | 612 |
| Moshi | T5 | 229 | 255 | 712 |
| GPT-Realtime | T1 | 1210 | 1338 | 1851 |
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