harmonic and individual line plus noise (speech encoding) (HILN)

Harmonic and Individual Line Plus Noise (HILN) is a music-optimized parametric compression technique characterized by low data rates of 4 kbit/s to 16 kbit/s.

In this parametric coding, harmonic and dominant frequency components as well as noise components are extracted from the audio signal and then coded separately. HILN is used in MPEG-4 and can vary the audio frequency and playback speed independently during decoding.