A data-driven predictive maintenance tool for guitarists that quantifies instrument string degradation through real-time spectral analysis.

Version: 1.0 (Feature Complete) Platform: .NET MAUI (Windows, Android, iOS, macOS) License: MIT

Guitarists traditionally rely on subjective "ear-feel" to determine when to change strings. This project eliminates that ambiguity by translating acoustic signals into quantifiable physical data, providing a logical threshold for string replacement.

This is not a tuner app. This is an acoustic degradation analysis engine that quantifies string wear through timbre fingerprinting rather than pitch detection.

• Spectral Centroid Tracking: Measures the "center of mass" of the frequency spectrum to detect tonal darkening
• High-Frequency Energy Ratio: Monitors amplitude decay of upper harmonics (5kHz-15kHz) relative to the fundamental
• Native C# DSP: Cross-platform FFT analysis via FftSharp library (no external dependencies)

• Register multiple guitars with make, model, and type classification
• Track string sets with individual gauge configurations
• Pair strings to guitars with installation date tracking
• Automatic baseline capture for fresh string spectral fingerprints

• Time-series decay tracking with SQLite persistence
• Linear regression-based replacement predictions
• Health status indicators (green/yellow/red) with configurable thresholds
• Estimated replacement date calculation

• Interactive decay trend charts via LiveCharts2
• Selectable metrics: Decay %, Spectral Centroid, HF Energy Ratio
• Historical measurement comparison

Frontend:  .NET MAUI (C#) - Strict MVVM Pattern
Backend:   Native C# DSP via FftSharp (cross-platform)
Database:  SQLite via sqlite-net-pcl
Fallback:  Python engine for desktop debugging/validation

• Sample Rate: 48,000 Hz
• Bit Depth: 24-bit PCM
• Buffer Size: 4096 samples (85.3ms @ 48kHz)
• FFT Size: 8192-point (zero-padded)

SonicDecayAnalyzer/
├── src/
│   ├── SonicDecay.App/          # .NET MAUI Application
│   │   ├── Models/              # 5 entity classes
│   │   ├── ViewModels/          # 9 MVVM view models
│   │   ├── Views/               # 8 XAML pages
│   │   ├── Services/            # 14 service interfaces + implementations
│   │   ├── Converters/          # 14 value converters
│   │   └── Platforms/           # Platform-specific audio capture
│   │
│   └── SonicDecay.Engine/       # Python reference implementation
│       ├── analysis.py          # FFT pipeline
│       ├── spectral.py          # Metric calculations
│       └── tests/               # Algorithm validation (pytest)
│
├── docs/                        # Technical documentation
└── tests/                       # C# unit tests

• Microsoft.Maui.Controls - Cross-platform UI framework
• sqlite-net-pcl (v1.9.172) - SQLite database access
• FftSharp (v2.2.0) - FFT computation (MIT license)
• LiveChartsCore.SkiaSharpView.Maui (v2.0.0-rc3.3) - Chart visualization

• NumPy / SciPy - Signal processing
• pytest - Algorithm validation

• .NET 9.0 SDK
• Visual Studio 2022 or Rider with MAUI workload
• Platform SDKs (Android SDK, Xcode for iOS/macOS, Windows SDK)

# Restore dependencies
dotnet restore

# Build for Windows
dotnet build -f net9.0-windows10.0.19041.0

# Build for Android
dotnet build -f net9.0-android

# Build for iOS (requires macOS)
dotnet build -f net9.0-ios

This project is built upon a fusion of:

• Acoustic Science: Understanding of harmonic series and digital audio processing
• Advanced Mathematics: Implementation of FFT algorithms and frequency domain analysis
• Software Engineering: Rigorous design patterns (MVVM, Repository, SOLID) to manage complex signal data flows

• CLAUDE.md: Complete technical specification and architectural contract
• docs/: Technical documentation
  • database-schema.md - SQLite schema reference
  • standards.md - Coding conventions and architecture
  • commit-message-guide.md - Commit message format

Last Updated: 2026-03-08