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VOICE MODEL COMPARISON
AI VOICE COMPARISON

Gemini 3.1 vs OpenAI Realtime Showdown

Two leading voice AI models tested on the same scenarios, bilingual healthcare calls and noisy factory floor transcription.

See the comparison See benchmarks
Gemini 3.1 Flash
Best for live multilingual conversations, voice agents, real-time translation.
EN ↔ ES auto-switch · 5 turns
Gemini 3.1 Flash · 44.3s
OpenAI Realtime 2
Best for accurate transcription, noisy environments, structured outputs.
whisper · 123 word timings
GPT Realtime 2 · marin voice
EN ↔ ES auto-switch · 5 turns
whisper · 123 word timings
Gemini 3.1 Flash · 44.3s
GPT Realtime 2 · marin voice
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Real Scenarios Side-by-Side Audio Live Metrics Detailed Insights
SIDE-BY-SIDE SCENARIOS

Two scenarios. One audio source each.

Hit play on either scenario and watch both AI models interpret the same audio in real time. Same input, different intelligence.

01 · HEALTHCARE CALL
SCENE
Son calls Bayview Family Clinic to book a follow-up for his mother Maria after surgery.
SAMPLE CONTEXT
5-turn bilingual call. Halfway through, Maria takes over in Spanish to describe her symptoms. Each AI must auto-switch language between English and Spanish to match the caller.
Gemini
0:43
GOOGLE
Gemini 3.1 Flash Live
VOICE MODELPuck (en) · Aoede (es)
AUDIO IN/OUT16 kHz / 24 kHz
LANGUAGESAuto-detect EN ↔ ES
ARCHITECTUREWebSocket · per-session
Press play to see the transcript appear live…
Gemini · audio
0:00 / 0:44
OpenAI
0:45
OPENAI
GPT Realtime 2
VOICE MODELmarin (female · pro)
AUDIO IN/OUT24 kHz / 24 kHz
LANGUAGESAuto-detect EN ↔ ES
ARCHITECTUREWebSocket · server VAD
Press play to see the transcript appear live…
OpenAI · audio
0:00 / 0:45
THE NUMBERS

Rated across seven metrics...

Cost FACT
Audio-out is ~5.3× cheaper on Gemini ($12 vs $64/M); audio-in ~10.7× cheaper ($3 vs $32/M). Decisive gap for any real call volume.
Gemini 3.1 Flash Live
$3/M audio in · $12/M audio out — cheapest by a wide margin
5/5
GPT-Realtime-2
$32/M audio in · $64/M audio out — premium realtime pricing
2/5
Context Window FACT
Effective tie — 131K vs 128K. Both still tight for long agent sessions; neither hits 5/5. Gemini edges on max output (65K vs 32K).
Gemini 3.1 Flash Live
131K context · up to 65K max output tokens
4/5
GPT-Realtime-2
128K context · up to 32K max output tokens
4/5
Language Options FACT
Gemini: 90+ languages in one native audio-to-audio model. OpenAI: no published language count for Realtime-2; strong multilingual sits in the separate Realtime-Translate model (70 in → 13 out), requiring orchestration.
Gemini 3.1 Flash Live
90+ languages in one native audio-to-audio model
5/5
GPT-Realtime-2
No published count; strong multilingual sits in separate Realtime-Translate model (70 in → 13 out), requiring orchestration
3.5/5
Interruption Handling HANDS-ON
Both have native barge-in. OpenAI feels faster and recovers more gracefully with verbal acknowledgment. Gemini offers finer VAD tuning but lacks a barge-in on/off toggle.
Gemini 3.1 Flash Live
Native barge-in · configurable VAD sensitivity · no on/off toggle
4/5
GPT-Realtime-2
Native barge-in · faster turnaround · graceful verbal recovery
4.5/5
Pronunciation Accuracy HANDS-ON
Tested with numerals and proper nouns. OpenAI hallucinates with numbers and struggles with proper nouns. Gemini is reliable on both — critical for healthcare safety where wrong dosages or misread patient names are unacceptable.
Gemini 3.1 Flash Live
Reliable on numerals and proper nouns
5/5
GPT-Realtime-2
Hallucinates numbers · struggles with proper nouns
3.5/5
Voice Quality HANDS-ON
Both clear the robotic-TTS bar with natural, expressive speech. OpenAI edges slightly ahead on naturalness in test scripts; Gemini remains production-grade and well above baseline.
Gemini 3.1 Flash Live
Natural prosody · production-grade output
4.5/5
GPT-Realtime-2
Most natural in testing · expressive and consistent
5/5
Tool Calling Decision HANDS-ON
Tested on when to invoke a tool versus answer directly. OpenAI is more consistent at handling ambiguous tool-vs-no-tool cases; Gemini works but misjudges more often.
Gemini 3.1 Flash Live
Functional · less consistent on tool-vs-no-tool judgment
3/5
GPT-Realtime-2
Reliable tool decisions · handles ambiguity well
4/5
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