Original narration synthesized on October 1, 2026 with the built-in macOS Samantha voice. Script: This is an original Podcastools demonstration. Compare the same recording with steady fan noise, electrical hum, and high frequency hiss before and after processing. Added noise is a reproducible simulation, not a field recording. Seed 1701. Fan: smoothed white noise plus 48 Hz rumble; hum: 60/120/180 Hz tones; hiss: high-frequency noise. Before: mono 44.1 kHz 16-bit PCM. After: processed through the same browser Web Audio filters used by the tool. Settings: fan/60, hum60/60, hiss/60. No model, microphone recording, or third-party recording was used.