Headroom

n. space above the head (in a doorway, car, etc.)

This article is about the audio signal processing term. For other uses, see Headroom (disambiguation). 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.
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Noun
1. vertical space available to allow easy passage under something
(synonym) headway, clearance
(hypernym) room, way, elbow room
2. the capacity of a system to reproduce loud sounds without distortion
(synonym) dynamic headroom
(hypernym) high fidelity, hi-fi

(n.)
See Headway, 2.
  

The vertical distance between the top of the superstructure of a vehicle or the head of a person and any obstruction above them. See also overhead clearance. 15/7/2000