Voice Loop

English | Deutsch

Voice Loop

Talk to your copilot directly – without Claude, without push-to-talk (VR-friendly), fully local and without a language model. Only the optional small talk can use one.

Microphone → Silero VAD (end of utterance) → Whisper (transcript) → Router ─┬→ copilot commands → Input module
                                                                            ├→ queries, checklists
                                                                            ├→ ATC module
                                                                            └→ small talk (optional, read-only)
                      Speech output (Kokoro / Supertonic) ←─────────────────┘

Switching it on

1. Dashboard → Callouts → Voice → Voice loop: tick the box and choose the microphone. Applies immediately.
2. On first start Duopilo downloads Whisper (base-q5_1, ~60 MB) and Silero VAD (~2 MB) to %LOCALAPPDATA%\Duopilo\models.
3. For commands that operate the aircraft, input must be unlocked too.

Settings live in %LOCALAPPDATA%\Duopilo\voice-settings.json. Don't edit the voice-settings.json next to Duopilo.exe – that's only the template and gets overwritten by updates.

The voice loop runs only in the tray instance.

How it works

• Open mic. Silero VAD detects speech; after 0.7 s of silence the utterance goes to Whisper.
• Half duplex. While the copilot or ATC speaks (and 350 ms after), the mic is muted – Duopilo doesn't hear itself. While you speak, callouts wait briefly; only warnings and time-critical PM callouts (100 knots, V1, Rotate, Positive climb, Spoilers, Reverse, Decel, 70 knots, radio altitudes, Minimum, Retard) cut in.
• German or English per utterance. Numbers are normalized: "Flaps one", "Flaps 1", "Flaps won", "Klappen eins" are the same.
• Router: a station name ("Frankfurt Delivery", "Langen Radar", "Shanwick") or your callsign at the start of a call or end of a readback → ATC. Everything else → copilot. "Duopilo, …" always goes to the copilot.
• Only while the sim runs. Not connected, no flight loaded or paused → the mic isn't evaluated (saves CPU), no ATC, no callouts; pending readbacks and checklists freeze instead of expiring. The dashboard shows why ("inactive – Paused").

Wake word and addressing

Commands work without a wake word. To address the copilot explicitly – e.g. during a checklist – use "Kopilot, …" (fixed), the first officer's name ("Sam, gear up") or "Duopilo, …" if Whisper transcribes it clearly. commands.requireWakeWord makes the wake word mandatory.

Commands

Fixed patterns in English and German. Every action of every aircraft profile has a voice command (enforced by a test; full list with examples in VoiceCommandCatalog.cs).

Area	Examples
Configuration	Gear up/down, Fahrwerk ein/aus · Flaps 0/1/2/3/Full, Klappen null/eins/voll · Speedbrake retract/half/full · Arm/Disarm spoilers
Brakes, lights, signs	Autobrake low/medium/max/off · Landing lights on/off · Strobe on/auto/off · Beacon on · Taxi light on · Nav lights on · Seat belts on/off · No smoking on/auto
Electrics, APU	Batteries on/off · External power on/off · APU start · APU master on/off · APU bleed on/off
Anti-ice	Engine anti ice on, Engine one anti ice on · Wing anti ice on · Probe heat on/auto
EFIS, FCU	QNH one zero one three · Baro standard · Altitude five thousand · Flight level one two zero · Speed two five zero · Heading zero niner zero · Managed speed · Vertical speed minus one thousand · Autopilot one on · Approach on · ND mode ARC/ROSE NAV/PLAN · ND range one hundred sixty · Expedite climb
Transponder, TCAS, radio	Squawk seven thousand · Transponder standby/auto · Altitude reporting on/off · TCAS TA/RA · TCAS traffic all/above/below/threat · COM one standby one two one decimal five · Swap COM one

Note: "Klappen ein" is not accepted (too close to "eins").

Execute + callout (default)

As in a real crew, your command is the instruction: the copilot executes right away and calls it out once the aircraft has accepted it – "Speed two five zero set", "Altitude five thousand set"; gear and flaps once the position is reached ("Gear down, three green", "Flaps two").

Reply	Meaning
"Not confirmed"	the aircraft didn't accept the value
"Unable"	an interlock blocked it (e.g. batteries off in flight)
"Input disabled"	input is locked
"Say again"	not understood, or two commands in one utterance

Readback with "Confirm"

A readback only comes when recognition was uncertain (Whisper confidence below commands.minConfidence, default 0.6) or the action needs a confirmation (see Input Module):

1. Duopilo reads back: "Flaps one".
2. "Confirm", "Correct", "Affirm" (also "Korrekt") → executed. "Negative" / "Cancel" → "Cancelled".
3. "Yes", "OK", "Roger" alone confirm nothing → "Say again".

"Confirm" only counts after the readback has been spoken completely, in an utterance started afterwards. Without an answer the action expires after 60 s. Critical actions ask a second time with a caution ("Caution, autothrust off. Confirm autothrust off?").

"executeWithCallout": false sends every command through the readback.

Queries

Answered with the plain callout only:

Question	Answer (example)
Speed check	Speed two five zero (on the ground: Ground speed one two)
Altitude check	Altitude five thousand / Flight level three five zero
Fuel check	Fuel twelve point four tons
Fuel versus plan, Landing fuel	Fuel thirty four point one, two point two below plan, landing fuel six point eight
Next waypoint	Hendy, one hundred twenty miles, E T A zero three four two
ETA	E T A zero four one eight
Top of descent	Top of descent eighty five miles, E T A zero three one two
Traffic check	Traffic, 2 o'clock, 5 miles, 1000 feet above, descending / No traffic
Wind check, Temperature	Wind two seven one at forty five · Temperature minus forty seven
Squawk check	Squawk two three four zero
Station check, Which frequency	Montreal Center, one three two decimal two five
Engine check	Engines normal / Engine two not running / N1 split
Gear, Flaps, Speedbrake, Spoilers, Seat belts, APU, Baro, Heading check	Gear down · Flaps one · Speedbrake retracted · …

Plan-based answers need a SimBrief plan – otherwise "Unable".

Acknowledgment ("Check" / "Copy")

Important messages expect "Check" or "Copy": fuel warnings, safety cautions and warnings, ATC squawk/frequency deviations, TCAS RA. Without an answer Duopilo repeats once after ~10 s, then escalates with an attention tone and the dashboard alert ACK_MISSING. A late "Check" or the end of the condition clears it. Configure under acknowledge in voice-settings.json.

Checklists

Challenge-response after the Airbus Normal Checklist:

Say	German
Before start checklist	Checkliste vor dem Anlassen
After start checklist	Checkliste nach dem Anlassen
Before takeoff checklist	Checkliste vor dem Start
Approach checklist	Checkliste Anflug
Landing checklist	Checkliste Landung
After landing checklist	Checkliste nach der Landung
Parking checklist	Checkliste Parken

Duopilo reads the challenge, waits for your answer and compares it with the sim where it can (signs, fuel, baro, beacon, flaps, autothrust, autobrake, landing memo, spoilers, APU, engines). A deviation is called out ("Beacon off") and the item stays open; if it still deviates, the checklist continues and lists open items at the end.

"Standby" holds · "Skip" / "Next item" skips · "Say again" repeats · "Stop checklist" interrupts. While a checklist runs, every utterance without the wake word is an answer – commands need "Kopilot, …".

Control

Say / press	Effect
"Kopilot pause" / "Kopilot resume" (also "Kopilot weiter", "Duopilo pause")	mute / unmute voice input – callouts keep running
Ctrl+Alt+K (system-wide, hotkeys.mute)	same
"Say again"	repeats the last reply
"Briefing"	first officer introduction

Radio

Calls go straight to the ATC module – like atc_transmit, just without Claude. "Say again", "Affirm" and "Negative" without a station go to whoever spoke last. If ATC is off or the SimBrief plan is missing: "ATC unavailable".

Settings (voice-settings.json)

Comments are allowed. Everything applies only with "enabled": true.

Section	What
microphone	device (part of the name, empty = default), VAD threshold, minimum length, silence until end of utterance, tail after callouts
recognition	Whisper model (tiny/base/small, -q5_1/-q8_0), cpu/gpu, threads, language auto/de/en, vocabulary hint
voices	copilot voice (kopilot), copilot and ATC volume
hotkeys	mute hotkey
commands	wake words, requireWakeWord, confirmation timeout, executeWithCallout, minConfidence
acknowledge	on/off, repeatAfterSec, rules that expect "check"/"copy"
atc	additional callsigns and stations, callsign from MSFS
callouts	active and muted rules, silentWhenPaused, taxi speed warning

Microphone: if the chosen device is missing (VR headset still off), Duopilo uses the default device and switches automatically once it appears.

Performance

Default: Whisper on the CPU with 4 threads, only after you've spoken. Faster: a fixed language ("language": "en"), "audioContext": 768 or tiny-q5_1. Better German: small-q5_1 (~190 MB). gpu tries CUDA, then Vulkan, else CPU – next to MSFS in VR that can cause stutters.

Diagnostics

• Status: duopilo_status → voiceLoop, the dashboard next to the microphone, or http://127.0.0.1:5155/voice.
• The log shows every recognized utterance with timing and target, discarded ones with the reason, and a warning if the mic only delivers silence (muted, or Windows privacy setting Let desktop apps access your microphone off).
• More detail: "Logging": { "LogLevel": { "Duopilo.Voice": "Debug" } } at the top level of appsettings.Local.json.

Licenses: Whisper.net and whisper.cpp (MIT), Silero VAD (MIT), NAudio (MIT).