# silero-vad against the energy threshold in mavwaked

*Measured 2026-08-09 on homesrv. V-487, stage one of two.*

mavwaked decided an utterance had started by comparing frame energy to an
adaptive floor. That answers "is this frame loud". A fan, a door and a
television are all loud, and every utterance mavwaked accepts becomes a turn.

silero-vad answers "is this frame speech". It is 2.3MB of ONNX and it replaces
the comparison and nothing else. The speech hold, the silence hold, the length
cap and the utterance buffer are the same state machine either way.

## What it declines

Speech is the four piper fixtures `mavsttd` already scores against, so nothing
of the owner's voice is committed. Non-speech is white noise at the same RMS as the clip beside it. That is the
cheapest thing that fools an energy floor.

| clip | silero, speech frames on speech | silero on noise | energy on noise |
|---|---|---|---|
| ru_fact.wav | 59 | 0 | 68 |
| ru_query.wav | 69 | 0 | 79 |
| ru_reminder.wav | 80 | 0 | 89 |
| en_act.wav | 90 | 0 | 99 |

The energy threshold accepts every noise clip as a complete utterance. Silero
calls not one frame of any of them speech, and still hears all four spoken
clips. `TestSileroHearsSpeechAndDeclinesNoise` is that table.

White noise is a floor, not a proof. It says nothing about a television, which
is speech, or about a fan, which is narrowband. Those need room recordings and
this box has none.

## What it costs

`BenchmarkSileroFrame` on the homesrv laptop (Ryzen 5 5600U), one 30ms frame
through the model including the re-chunking:

    509µs per frame

That is 1.7% of one core, on the slower of the two machines. The detector runs
on the workstation beside the microphone, never on the GPU. This number is what
says it does not need one.

## The window is 512 samples, not 480

`cmd/mavwaked/main.go` claimed the frame contract matched silero's input
exactly. That was true of silero v4. Version 5 takes exactly 512 samples at 16kHz, plus 64 samples of context from
the previous window. So `sileroVAD` buffers across capture frames, and a frame
completing no window inherits the previous probability. `TestSileroRechunksAcrossFrames` pins it.

## Still an energy gate by default

`-vad-model` is empty in the code default, so a deployment that does not pass
it runs exactly what shipped before. Barge-in is untouched and deliberately so. It reads frame energy while she is
speaking, which is a different question from whether the frame is speech.

## Not done here

The wake word. This is stage one of the two V-487 asks for. The second needs a
keyword model that does not exist yet. The pretrained openWakeWord keywords are
English, and a Russian one has to be trained. Until then anything spoken near
the microphone still becomes a turn. It is now merely required to be speech.