Hush Little PC

A tiny Windows tray app that automatically mutes your speakers after a configurable period of keyboard and mouse inactivity.

Step away from your PC and Hush Little PC quietly mutes the sound. Click the tray icon to turn it on or off.

Features

• Idle muting: mutes your default playback device after 1 to 1440 minutes (24 hours) without keyboard or mouse input.
• One-click toggle: left-click the tray icon to enable or disable. The icon changes colour to show the current state.
• Native tray menu: right-click for Enabled, Mute now, Settings and Exit. It uses the standard Windows menu, so it matches the Windows 11 look and follows light/dark mode.
• Unmute when I come back (optional): only unmutes if Hush Little PC did the muting, so a mute you set yourself is never undone.
• Stay unmuted while audio is playing (optional): handy for watching videos or listening to music without touching the PC.
• Mute on output change (optional): mutes the new device when Windows switches the default playback device, for example when Bluetooth headphones connect or you switch to speakers.
• Notification with an Unmute button (optional): a native Windows notification when Hush Little PC changes an unmuted device to muted, so you can undo it with one click. Already-muted devices do not trigger a notification.
• Start with Windows (optional): per-user startup entry, no admin rights needed.
• Follows your output device: switching to headphones, HDMI or Bluetooth just works.

Requirements

• Windows 10 or 11
• .NET 8 Desktop Runtime for the portable exe (not needed for the Microsoft Store version, which bundles its own runtime, or if you publish self-contained, see below)

Install

• Microsoft Store: install from Hush Little PC on the Microsoft Store. Updates are delivered by the Store.
• Portable: download HushLittlePC_<version>_x64-portable.exe from the Releases page (needs the .NET 8 Desktop Runtime).

Build

You need the .NET 8 SDK.

dotnet publish -c Release -r win-x64 --self-contained false -p:PublishSingleFile=true

The exe is created at bin\Release\net8.0-windows10.0.19041.0\win-x64\publish\HushLittlePC.exe.

To produce an exe that runs without the .NET runtime installed (larger file), use --self-contained true instead.

Pre-commit checks

Install pre-commit and enable the hooks:

python -m pip install pre-commit
pre-commit install

Before each commit, the hooks check whitespace, final newlines, merge-conflict markers and YAML syntax, and the commit message is checked against Conventional Commits. Changes to C# files or the project file also trigger a Release build and the unit tests. Run all checks manually with pre-commit run --all-files.

Run the core unit tests directly with dotnet test tests/HushLittlePC.Tests.csproj -c Release. They cover idle-threshold muting, manually muted and app-muted devices, return-from-idle unmuting, skipping active playback, output-change gating, notification eligibility, mute transitions, enabled-state toggling, and settings defaults, limits and serialization. Windows-specific audio hardware, toast delivery, startup registration, tray rendering, and single-instance behavior still require Windows integration testing.

Usage

Action	Result
Left-click the tray icon	Enable or disable idle muting
Right-click the tray icon	Open the menu (Enabled, Mute now, Settings, Exit)

Settings

Setting	Description
Mute after N minutes	Idle time before muting. Slider goes up to 2 hours; type up to 24 hours.
Enable Hush Little PC	Turns all muting on or off. Same as clicking the tray icon.
Unmute when I come back	Unmutes on activity, only if Hush Little PC muted it.
Stay unmuted while audio is playing	Skips muting while sound is being output.
Mute when the audio output changes	Mutes the new default playback device whenever Windows switches outputs.
Show a notification when audio is muted	Windows notification with an Unmute button each time audio is muted.
Start Hush Little PC with Windows	Portable exe: adds an entry under HKCU\Software\Microsoft\Windows\CurrentVersion\Run. Store version: enables its startup task (manage it under Settings > Apps > Startup; if you turn it off there, Windows only lets you turn it back on there).

Settings are saved with Save changes, which is enabled only after an option changes. Closing with unsaved edits asks for confirmation before discarding them.

Settings are saved to %AppData%\HushLittlePC\settings.json. If you edit the file by hand, the idle time is kept within 1 to 1440 minutes. For the Store version Windows redirects this folder to the package's private storage, and it is removed when you uninstall.

How it works

• Idle time comes from the Win32 GetLastInputInfo API, checked once per second. Only keyboard and mouse input counts as activity.
• Notifications use the Windows Community Toolkit notifications library (Microsoft.Toolkit.Uwp.Notifications).
• Muting uses the Windows Core Audio API (through NAudio) on the current default playback device, which is looked up again on every check so output switches are picked up.
• Muting is tracked so the app only unmutes what it muted itself. The decision logic lives in IdleMutePolicy and is covered by unit tests.
• Startup uses the per-user Run registry key for the portable exe and the manifest's StartupTask for the Store (MSIX) package, because packaged apps can't write to the Run key.
• Output changes are detected through the Windows Core Audio device notifications (the default playback device changing).
• "Audio is playing" is detected from the device's master peak meter.
• The tray menu is a native Win32 popup menu. Light/dark theming uses undocumented uxtheme.dll calls; on versions of Windows that lack them, the menu simply stays light.

Project layout

Path	Purpose
Program.cs	Entry point and single-instance check
TrayApp.cs	Tray icon, idle-check timer, mute orchestration
IdleMutePolicy.cs	Pure decision logic: when to mute, unmute or notify
MuteTransition.cs	Mutes a device only if needed and reports its prior state
NativeMenu.cs	Native Win32 tray menu
Notifier.cs	Native Windows notifications with an Unmute button
SettingsForm.cs	Settings window
SettingsModel.cs	Settings type and JSON serialization (no Windows dependencies, so it is unit-tested)
Settings.cs	Settings file storage and the start-with-Windows logic (registry or MSIX startup task)
Native.cs	Idle-time, audio-device and output-change helpers
tests/	MSTest unit tests for the platform-independent logic
packaging/	MSIX manifest and Store assets
store/, docs/, resources/	Store listing art, README images, embedded notification icon
.github/	CI, release and commit-lint workflows, Dependabot config, MSIX packaging script

Contributing

• Pull request titles must follow Conventional Commits (for example fix: ..., feat: ...), because the title becomes the commit message on main and drives versioning. CI lints the title on every pull request, and the check is required before merging. The pre-commit hook gives the same feedback locally for individual commits.
• CI builds the app and runs the unit tests on every pull request and push to main.
• When CI succeeds on main, semantic-release creates the version tag and GitHub release, attaches the portable exe, and submits the MSIX package to the Microsoft Store.
• Store publishing needs these repository settings: variables MSIX_IDENTITY_NAME, MSIX_PUBLISHER and MSIX_PUBLISHER_DISPLAY_NAME, and secrets TENANT_ID, SELLER_ID, CLIENT_ID, SECRET_VALUE and STORE_ID. The release workflow stops early with a clear message if the variables are missing.
• Enable the pre-commit checks to catch problems before pushing.

Uninstall

1. Untick Start Hush Little PC with Windows in Settings.
2. Right-click the tray icon and choose Exit.
3. Delete the exe and, if you like, the %AppData%\HushLittlePC and %LocalAppData%\HushLittlePC folders (the latter holds the notification icon).

For the Store version, uninstall it from Settings > Apps > Installed apps instead; that also removes its settings.

Limitations

• "Mute when the audio output changes" reacts to Windows changing the default device (Bluetooth, USB, HDMI, or picking another output). Plugging headphones into a wired 3.5 mm jack usually doesn't change the default device, so it won't trigger.
• Only the default playback device is muted, not every audio device.
• Idle detection is system-wide input only. Playing media without touching the keyboard or mouse counts as idle unless "Stay unmuted while audio is playing" is on.

License

This project is licensed under the MIT License.