Isolate the caller's voice

Real calls are noisy: keyboard clacks, café chatter, a car engine, room echo. That noise makes the agent mishear words and, worse, can trip false turn-taking and interruptions. input.voice_focus isolates the primary speaker and suppresses background audio before it reaches transcription, so the agent responds to the caller and not the room. Set it when you create or update the agent.

Model	Value	Use for
Near field	`near-field`	Headsets, handsets, and other close-talking mics. Default.
Far field	`far-field`	Phone speakerphone, conference rooms, drive-thru, laptop and car mics.

Match the model to how the caller is captured: a browser agent on a headset wants near-field; a phone or in-room agent wants far-field.

curl -X POST https://agents.assemblyai.com/v1/agents \
  -H "Authorization: $ASSEMBLYAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Drive-thru Assistant",
    "system_prompt": "You take drive-thru orders.",
    "voice": { "voice_id": "alba" },
    "input": { "voice_focus": "far-field", "voice_focus_threshold": 0.8 }
  }'

# pip install requests
import os
import requests

resp = requests.post(
    "https://agents.assemblyai.com/v1/agents",
    headers={"Authorization": os.environ["ASSEMBLYAI_API_KEY"]},
    json={
        "name": "Drive-thru Assistant",
        "system_prompt": "You take drive-thru orders.",
        "voice": {"voice_id": "alba"},
        "input": {"voice_focus": "far-field", "voice_focus_threshold": 0.8},
    },
)
resp.raise_for_status()
print(resp.json())

// Node 18+ has fetch built in
const res = await fetch("https://agents.assemblyai.com/v1/agents", {
  method: "POST",
  headers: {
    Authorization: process.env.ASSEMBLYAI_API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    name: "Drive-thru Assistant",
    system_prompt: "You take drive-thru orders.",
    voice: { voice_id: "alba" },
    input: { voice_focus: "far-field", voice_focus_threshold: 0.8 },
  }),
});
const data = await res.json();
console.log(data);

Field	Type	Required	Notes
`input.voice_focus`	string	No	`near-field` (default) or `far-field`.
`input.voice_focus_threshold`	number	No	`0.0` to `1.0`, default `0.7`. Higher suppresses more aggressively. Requires `voice_focus`.

Voice Focus is applied when the speech-to-text connection opens, so set it at agent-create or connect time. For how the models and threshold behave under the hood, see Voice Focus in the Streaming docs.

Getting started

Create & manage agents

Agent behavior

Conversational experience

Deploy

After a session

Reference

API reference

Isolate the caller's voice