Low fidelity or lo-fi describes a sound recording which contains technical flaws such as distortion, hum, or background noise, or limited frequency response. The term "low-fidelity" is used in contrast to the audiophile term high fidelity or "hi-fi", which refers to stereo equipment that very accurately reproduces music without harmonic distortion or unwanted frequency emphasis or resonance. The ideas of lo-fi are taken to extremes by the genre or "scene" of no fidelity, or no-fi. Some lower-budget recordings from the 1970s and 1980s have a "lo-fi" sound due to the limitations of the analog recording and processing techniques, which introduced unwanted artifacts such as distortion and phase problems. In some recordings, however, high fidelity recording is purposely avoided, or the artifacts such as simulated vinyl record crackles are deliberately retained or added in for aesthetic reasons.
Some unique aural qualities are available only with "low-tech" recording methods, such as recording on tape decks, or using analog sound processors (e.g., analog compressors or reverb units). The lo-fi aesthetic has even contributed to musical subgenres, such as the "lo-fi" subgenre of indie rock and a great deal of punk rock. Lo-fi techniques are espoused by some genres outside the indie rock world, particularly by certain heavy metal bands (especially within the sludge and black metal scenes), where the very low-quality of the recording has become a desirable quality, as it is associated with authenticity, as well as a "darker" sound.