Nazar Kozak

Staff Software Engineer at Yahoo · IEEE Senior Member
On-device AI, mobile SDK architecture, speech signal processing

Publications

On-Device Disfluency Detection with Voice Stress Association Analysis: A Mobile Framework Validated on SEP-28K

Nazar Kozak · Submitted to IEEE Signal Processing Letters, 2026

We present DisfluoSDK, an on-device framework for real-time speech disfluency detection and voice stress analysis on iOS. CNN models (617K params, 1.2 MB) achieve sub-millisecond CoreML inference. Evaluated on SEP-28K with episode-grouped cross-validation.

Voice Stress Markers Are Orthogonal to Speech Disfluency Labels: A Large-Scale Analysis on SEP-28K

Nazar Kozak · engrXiv Preprint, 2026

Large-scale analysis (N=14,645) showing all correlations between voice stress features and disfluency labels are negligible (|r| < 0.05, Cohen's d < 0.04). Supports separating stress and disfluency assessment in multimodal systems.

Adaptive Baseline Calibration for Voice Stress Assessment in Speech Disfluency Monitoring

Nazar Kozak · engrXiv Preprint, 2026

Welford-based adaptive baseline algorithm for per-speaker voice stress calibration. Fixed thresholds overestimate stress (61.4% high-stress); adaptive approach produces symmetric distribution. YIN pitch detection achieves 98.1% F0 rate.

Dynamic Multidex Loading for Cross-Platform SDK Integration

Nazar Kozak · engrXiv / Zenodo, 2026

A system for runtime DEX loading on Android that solved the 65K method limit for mobile ad mediation SDKs. Deployed at Appodeal, serving millions of apps.

Google Scholar · ORCID: 0009-0001-8858-6098 · GitHub · nzrkzk@gmail.com