Voice pipeline layer comparison
Addressee detection vs voice activity detection
VAD hears that speech happened. Addressee detection decides whether it was meant for your device.
Architecture comparison
VAD and addressee detection ask different questions of the same audio.
VAD is cheap, fast, and belongs in every pipeline. It just cannot tell who the speech was for.
That matters in a crowded room, or on a noisy one-to-one call. Every unaddressed utterance still runs your full stack.
VAD: detects that speech is occurring. Selective Auditory Attention (SAA): detects whether that speech is directed at the device.
| Layer | Core question it answers | When it runs | Decides who is addressed? |
|---|---|---|---|
| Noise cancellation and AEC | Is the audio cleaner? | Pre-ASR | No |
| Voice activity detection (VAD) | Is someone speaking right now? | Pre-ASR | No |
| Speaker diarization | Who spoke, and when? | Typically post-ASR | No |
| Wake word | Was the trigger phrase said? | Pre-ASR | Trigger phrase only |
| SAA addressee detection | Is the device being addressed, right now? | Pre-ASR, in real time | Yes |
How they relate
VAD and SAA are complementary: adjacent gates, different questions.
A bystander, a second speaker, TV audio: VAD treats them all the same. Only SAA, running right after it, tells them apart.
The addressee decision
What VAD cannot answer becomes false activations and wasted pipeline.
VAD and SAA gate on different signals. The gap between the two is where bystander triggers and side-conversation misfires happen.
the missing signal
Addressed or not addressed
VAD fires on the person addressing the device and the bystander behind them with equal confidence.
SAA adds the one signal VAD cannot produce: whether this utterance is directed at the device.
failure mode
Suppresses on uncertainty, never passes through
When addressee intent is ambiguous, SAA suppresses rather than forwards.
VAD has no equivalent: any speech that clears it reaches your ASR and model. Every close call gets expensive.
pipeline position
VAD first, then SAA, then ASR
SAA does not replace VAD. Order matters: VAD drops noise, SAA decides addressee, ASR transcribes only what SAA forwards.
latency
Decision in real time, pre-ASR
The routing decision returns before transcription begins, well inside typical latency budgets. No GPU required.
Performance
Measured on held-out multi-party sessions.
Published in our technical paper (arXiv:2604.08412); full methodology on the research page.
Fails closed under distribution shift; cross-lingual recall is still improving.
audio and video fusion
High accuracy on the addressee decision
Adds a camera stream alongside audio for stronger context.
audio-only
Accurate enough to gate before STT
No video stream required. Hosted cloud inference.
VAD decides that someone spoke. SAA decides who they meant it for.
The voice stack was never built to tell the two apart.
Common questions
What voice AI builders ask about VAD and addressee detection.
Does VAD detect who is being addressed?
No. VAD detects that someone is speaking, nothing more. It carries no information about who the speech is meant for.
In a room with several people, VAD fires on all equally. Addressee detection alone answers who it was meant for.
Can I replace my VAD with SAA?
No. VAD gates on speech presence cheaply, dropping silence and noise.
SAA runs after VAD and decides whether that speech is addressed to the device. You need both.
Does SAA run before or after VAD in the pipeline?
SAA runs after VAD and before ASR. VAD drops silence, SAA decides addressee, ASR transcribes only what SAA forwards.
SAA does not replace VAD; it adds the decision VAD cannot make.
Why does my VAD-based pipeline misfire on background speech?
Because VAD answers whether someone is speaking, not whether the device is being spoken to.
When a bystander or background audio clears the VAD threshold, it reaches your ASR and model exactly like a real turn.
There's no signal that the speech was never meant for the device. SAA adds it before ASR runs, and fails closed when uncertain.
What does SAA return that VAD does not?
An addressee decision. SAA returns a pre-transcription routing signal: device-addressed audio is forwarded, everything else is dropped.
VAD returns only a speech-presence signal.
Get in touch
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Last updated June 26, 2026