Javad Rajabzadeh | Senior Software Engineer

Optimally-Modified Log-Spectral Amplitude (OM-LSA): Post-Filtering for Speech Intelligibility

Sun, 19 Jul 2026 22:30:00 +0330

In digital signal processing and speech enhancement, spatial filtering techniques (such as Multi-channel Wiener Filtering or beamforming) effectively attenuate directional noise sources. However, residual non-stationary noise, diffuse background acoustic clutter, and reverberation often linger in the processed audio.

Applying traditional spectral subtraction or hard noise gate suppression to clean this residual noise causes severe musical noise artifacts—random, isolated spectral peaks that destroy human speech intelligibility and sound unnaturally harsh.

In this post, I explore the mathematical formulation and practical implementation of Optimally-Modified Log-Spectral Amplitude (OM-LSA) speech enhancement—a single-channel post-filtering technique designed by Israel Cohen and Baruch Berdugo that minimizes log-spectral amplitude estimation errors while preserving natural speech quality.

Real-Time Multichannel Speech Enhancement: Inverse-Free Rank-N Matrix Updating on Edge Hardware

Sun, 19 Jul 2026 22:00:00 +0330

In real-world acoustic engineering—especially on drones, autonomous robotic platforms, and ultra-low-power edge processors—enhancing speech signals in real time presents a severe computational bottleneck. Microphones mounted on moving drones or robotic units encounter heavy spatial interference, rotor harmonics, and turbulent wind noise.

While classical Multi-channel Wiener Filters (MWF) offer optimal spatial noise reduction, computing full spatial matrix inversions $\mathbf{R}_{nn}^{-1}(f)$ across hundreds of STFT frequency bins imposes an $\mathcal{O}(M^3)$ computational load that degrades battery life and causes latency spikes on embedded microcontrollers (such as STM32, ESP32, or ARM Cortex-M flight controllers).

Javad Rajabzadeh | Resume

Sun, 19 Jul 2026 00:00:00 +0000

Javad Rajabzadeh

Senior Software Engineer & Technical Lead
📍 Belgium / Remote | ✉️ ja7ad@live.com | 🌐 https://javad.dev | 🐙 GitHub | 💼 LinkedIn

Executive Summary

Results-driven Senior Software Engineer & Technical Lead with 9+ years of experience architecting high-performance backend microservices, decentralized blockchain networks (Layer 1, 2 & 3), and real-time AI/ML signal processing pipelines. Track record of leading cross-functional teams, publishing AWS Marketplace solutions, building ROS2 robotics modules, and contributing to core open-source infrastructure (TrustWallet Core, Meilisearch Go SDK).