No free plugin matches iZotope RX’s machine learning or spectral repair, but for removing hiss, hum, and ambient noise, the above four plugins are professional-grade and cost nothing.
Uses an adaptive noise floor estimation with adjustable thresholds. Unlike simple gates, it reduces noise across all frequencies proportionally.
CPU usage ~2–4% on modern i7. Minimal latency (under 10ms). Artifacts are controlled well in “Modern” mode.
Trained on thousands of voice and noise samples. Uses deep learning to isolate speech even under heavy background (e.g., traffic, café noise).
Extremely effective for steady-state noise (air conditioners, preamp hiss). Can cause “underwater” artifacts if reduction set too high (>30 dB).
