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Documentation Index

Fetch the complete documentation index at: https://docs.getpatter.com/llms.txt

Use this file to discover all available pages before exploring further.

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Silero VAD

SileroVAD is Patter’s bundled VADProvider — voice activity detection backed by the Silero ONNX model. It buffers incoming PCM frames, runs inference on fixed-size windows (256 samples at 8 kHz, 512 at 16 kHz), applies an exponential probability filter, and emits speech_start / speech_end transitions. Patter uses it to detect when the caller has started speaking so the agent can stop talking immediately (clean barge-in) and to gate STT activity on real speech instead of background noise.

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Install

Silero VAD ships with onnxruntime-node as an optional peer dependency (~210 MB): 
npm install getpatter onnxruntime-node@~1.18.0
The bundled silero_vad.onnx model file is included with the package.
Patter is currently tested against onnxruntime-node@~1.18.0. Versions 1.24+ removed listSupportedBackends and break the SDK; pin the version above until the SDK migration lands.

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Auto-loading

When you build a pipeline-mode agent and leave vad: undefined, Patter auto-loads SileroVAD.forPhoneCall() for you on the first call. If onnxruntime-node is not installed, Patter logs a single warning and continues without VAD — barge-in latency is higher but the call still works. To pick your own VAD or override the defaults, pass vad: explicitly. See the vad parameter on Agents (pipeline mode only).

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Constructor

The recommended entrypoint is the forPhoneCall factory — it pins the sample rate to 16 kHz (what Patter’s pipeline-mode audio bus uses) and applies the upstream Silero defaults. 
import { SileroVAD } from "getpatter";

// Recommended for telephony pipelines
const vad = await SileroVAD.forPhoneCall();

// Or, full control:
const vad2 = await SileroVAD.load({
  activationThreshold: 0.5,        // Silero `threshold`
  deactivationThreshold: 0.35,     // `neg_threshold = threshold - 0.15`
  minSpeechDuration: 0.25,         // seconds, `min_speech_duration_ms = 250`
  minSilenceDuration: 0.1,         // seconds, `min_silence_duration_ms = 100`
  prefixPaddingDuration: 0.03,     // seconds, `speech_pad_ms = 30`
  sampleRate: 16000,               // 8000 or 16000 only
  forceCpu: true,
});

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Phone-call preset (forPhoneCall)

Identical to load() but pins sampleRate to 16000 Hz — the only sample rate Patter’s pipeline-mode audio bus uses (8 kHz mulaw from Twilio is upsampled to 16 kHz PCM before reaching the VAD). All other parameters mirror the upstream Silero defaults from snakers4/silero-vad:
  • activationThreshold = 0.5 — upstream threshold
  • deactivationThreshold = 0.35 — upstream neg_threshold = threshold - 0.15
  • minSpeechDuration = 0.25 — upstream min_speech_duration_ms = 250
  • minSilenceDuration = 0.1 — upstream min_silence_duration_ms = 100
  • prefixPaddingDuration = 0.03 — upstream speech_pad_ms = 30
Override any field via the options object. Deployments that experience truncation on natural pauses can raise minSilenceDuration (e.g. 0.5–1.0 s): 
const vad = await SileroVAD.forPhoneCall({ minSilenceDuration: 0.5 });

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Usage in a pipeline agent

import {
  Patter,
  Twilio,
  DeepgramSTT,
  AnthropicLLM,
  ElevenLabsTTS,
  SileroVAD,
} from "getpatter";

const phone = new Patter({ carrier: new Twilio(), phoneNumber: "+15550001234" });

const vad = await SileroVAD.forPhoneCall();

const agent = phone.agent({
  stt: new DeepgramSTT(),
  llm: new AnthropicLLM(),
  tts: new ElevenLabsTTS({ voiceId: "rachel" }),
  vad,                                      // explicit, or omit to auto-load
  systemPrompt: "You are a helpful assistant.",
});

await phone.serve({ agent });

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When to use Silero VAD vs alternatives

  • Use Silero VAD for any pipeline-mode agent that needs sub-300 ms barge-in. It’s the production default.
  • Skip VAD (omit vad and don’t install the peer dep) only when you’re prototyping locally on a system where the ONNX runtime is awkward to install. Barge-in falls back to a sustained-voice heuristic that is slower and noisier.
  • Realtime engines (OpenAIRealtimeAdapter, GeminiLiveAdapter, UltravoxRealtimeAdapter) run server-side VAD inside the provider — agent.vad is ignored in engine mode.

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Notes

  • The model only supports 8000 or 16000 Hz inference. Other sample rates throw from processFrame.
  • The resolver probes multiple paths to find silero_vad.onnx, including under bundlers (Vite SSR, Next webpack, Bun). If you see model file not found, ensure getpatter is fully installed in your node_modules.
  • numFramesRequired() returns the int16 sample count needed per inference window (256 @ 8 kHz, 512 @ 16 kHz). Smaller chunks are buffered safely.

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What’s Next

Agents

The vad parameter on phone.agent({...}).

Krisp Filter

Proprietary noise / echo suppression.

DeepFilterNet

OSS noise suppression.

Pipeline mode

STT + LLM + TTS composition.