Lossy compression formats like MP3 and AAC reduce file size by discarding weaker signals in the frequency domain. Most of those discarded signals are harmonics — the subtle overtones that carry a recording's warmth, texture, and spatial character. The compressed file plays back at roughly the same loudness, but the sound is thinner, flatter, and less detailed than the original.

Harmony restores what compression removes. It regenerates harmonics from the remaining signal, recovering warmth and nuance across the full audio bandwidth.

How it works

Harmony generates both even-order harmonics (2nd, 4th, 6th) and odd-order harmonics (3rd, 5th, 7th) from the existing signal. Even-order harmonics add warmth and body; odd-order harmonics add definition and edge. The ratio between them is calibrated so that the result sounds natural — closer to the original recording, not artificially colored.

The processing covers the entire audio bandwidth evenly, from low frequencies through the upper range. There is no selective emphasis on any particular frequency band. This is deliberate: Harmony's purpose is faithful reconstruction, not tonal shaping.

Harmonics are generated at levels typically below -30 dB relative to the fundamentals. The effect is subtle but clearly audible — restoring the sense of depth and detail that compression strips away.

Bandwidth recovery

Beyond restoring in-band harmonics, Harmony recovers high-frequency content that compression discards entirely. MP3 encoding typically removes most information above 16 kHz. Harmony regenerates energy in this upper range, expanding the effective bandwidth of compressed sources back toward full-spectrum audio.

Where Harmony fits

Harmony is designed for any product that plays back compressed audio — which, in practice, means nearly every consumer audio device. It operates in the time domain with minimal computational overhead, making it suitable for resource-constrained embedded platforms.

Harmony pairs well with HD Remaster for a complete restoration chain: Harmony recovers lost in-band harmonics and bandwidth, then HD Remaster upsamples the result to true high-resolution audio.