Information AboutHeadroom |
| CATEGORIES ABOUT HEADROOM | |
| audio engineering | |
| broadcast engineering | |
| sound production technology | |
| sound recording | |
| sound | |
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In a digital Audio system, headroom is the amount by which digital full scale (FS) exceeds the permitted maximum level (PML) in DB (decibels). The EBU specifies a PML of 9 dB below 0 dBFS (-9 dBFS), thus giving 9 dB of headroom. Alignment level is an 'anchor' point, a reference level which exists throughout the system or broadcast chain, though it may have different actual voltage levels at different points in the analog chain. Typically, nominal (alignment) level is 0 dB, corresponding to an analog sine wave voltage of +4 dBu, or 1.23 Vrms (3.47 Vp-p). In the digital realm, alignment level is −18 dBFS. An alternative EBU recommendation allows 24 dB of headroom, which might be used for 24-bit master recordings, where it is useful to allow more room for unexpected peaks during live recording. Failure to provide adequate headroom is a common problem with CDs published in the late 1990s and early 2000s which often use heavy Level Compression (not to be confused with Data Compression by Codec s such as MP3 ), producing a very flat 'mushy' sound that lacks the sparkle provided by brief peaks from Percussion sounds. See Loudness War . AL = analog level SPL = sound pressure level SEE ALSO
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