AhSilence
Silence the ambient hum. Find your perfect quiet.
Overview
AhSilence is a native Android active noise cancellation (ANC) engine built with Jetpack Compose and Kotlin. It bridges the gap between complex digital signal processing (DSP) and human comfort by analyzing the environment for persistent, low-frequency hums (such as AC units or electrical drones) and emitting phase-inverted audio waves that mathematically neutralize acoustic disturbances.
The application runs a zero-allocation, GC-free hot loop, ensuring seamless destructive interference without frame drops or OS throttling.
Key Features
| Component | Implementation | User Benefit |
|---|---|---|
| FFT Engine | Custom Cooley-Tukey Radix-2 algorithm on real-time PCM buffers | Automatically detects the dominant background drone |
| Phase Calibrator | Continuous 360° trigonometric dial bound to memory blocks | Manual wave alignment to compensate for hardware/BT latency |
| OS Shield | Android Foreground Service with persistent notification | Keeps cancellation active while screen is locked |
| Stateless UI | StateFlow + Compose hoisted parameters |
Zero battery drain from unnecessary recompositions |
Architecture
AhSilence follows Clean Architecture with strict unidirectional data flow and complete isolation of the Android framework from core business logic.
graph TD
subgraph Presentation Layer
UI[Jetpack Compose UI]
VM[ControlViewModel]
end
subgraph Domain Layer
STATE((AcousticState))
PORT{AudioEngine Port}
end
subgraph Data Layer
SERVICE[ActiveHumService]
DSP[NativeAudioDSP]
FFT[FastFourier]
end
UI -->|Observes State| VM
UI -->|OS Intent| SERVICE
VM -->|Updates| STATE
VM -->|Injects Phase/Gain| PORT
SERVICE -->|Foreground Shield| DSP
DSP -->|Implements| PORT
DSP -->|PCM Buffer Math| FFT
classDef domain fill:#1E1E1E,stroke:#7F52FF,stroke-width:2px;
class STATE,PORT domain;
Data Flow
sequenceDiagram
participant M as Microphone
participant E as NativeAudioDSP
participant F as FastFourier (FFT)
participant U as Dashboard UI
participant S as Speaker (AudioTrack)
Note over M,E: 7-Second Ambient Scan
M->>E: Capture Raw PCM Buffer
E->>F: Compute Radix-2 FFT
F-->>E: Extract Dominant Frequency (Hz)
E-->>U: Push AcousticState Update
Note over U,S: User Calibration
U->>E: Inject Phase Offset (°) & Amplitude
Note over E,S: Continuous Emission Loop
loop GC-Free Hot Loop
E->>E: Synthesize Inverted Sine Wave
E->>S: Push Buffer (AudioTrack.WRITE_BLOCKING)
S->>M: Destructive Acoustic Interference
end
Project Structure
app/src/main/java/com/bted/ahsilence/
├── core/ # Cross-cutting concerns
│ ├── constants/AudioConstants.kt # Centralised magic numbers
│ ├── di/AudioEngineLocator.kt # Lightweight service locator
│ └── logging/AppLogger.kt # Structured logging facade
│
├── domain/ # Pure Kotlin — zero Android imports
│ ├── model/AcousticState.kt # Immutable single source of truth
│ └── port/AudioEngine.kt # DSP engine contract
│
├── data/ # Android framework implementations
│ ├── engine/FastFourier.kt # Radix-2 FFT math engine
│ ├── engine/NativeAudioDSP.kt # AudioRecord / AudioTrack pipeline
│ └── service/ActiveHumService.kt # Foreground service (OS Shield)
│
├── presentation/ # State management
│ └── ControlViewModel.kt # Jetpack Compose bridge
│
├── ui/ # Visual layer
│ ├── screen/DashboardScreen.kt # Main dashboard (Pro / Simple mode)
│ ├── component/ # Reusable UI elements
│ │ ├── CalibratorRing.kt # 360° phase dial
│ │ └── GainSlider.kt # Vertical amplitude fader
│ └── theme/ # OLED Black / Neon Amber design system
│ ├── Color.kt
│ ├── Theme.kt
│ └── Type.kt
│
└── MainActivity.kt # Entry point
Getting Started
Prerequisites
- Android Studio Ladybug (2024.2.1+)
- JDK 21+
- Physical Android device — emulators do not support low-latency hardware microphone FFT testing
Build
# Clone git clone https://github.com/ahmadhassan-bted/ahsilence.git cd ahsilence # Build debug APK ./gradlew clean assembleDebug # Run unit tests ./gradlew test # Lint check ./gradlew lint
Install
# Install on connected device
./gradlew installDebugTech Stack
| Layer | Technology |
|---|---|
| Language | Kotlin 2.0.21 |
| UI | Jetpack Compose (Material 3) |
| State | StateFlow + ViewModel |
| Audio Capture | AudioRecord (PCM 16-bit, 44.1kHz) |
| Audio Playback | AudioTrack (streaming mode) |
| FFT | Custom Cooley-Tukey Radix-2 |
| Background | Foreground Service (mediaPlayback) |
| Build | Gradle (Kotlin DSL) + Version Catalog |
| Min SDK | API 26 (Android 8.0) |
Contributing
See CONTRIBUTING.md for branch naming, commit conventions, and the non-negotiable architectural rules (zero-allocation hot loops, domain isolation, UI purity).
Security
AhSilence is fully offline — zero network calls, zero data collection, zero telemetry. See SECURITY.md.
Roadmap
See ROADMAP.md for planned features including multi-frequency cancellation, adaptive algorithms, and Bluetooth latency compensation.
License
Copyright 2025 Ahmad Hassan
Licensed under the Apache License, Version 2.0.
See LICENSE for details.