In mastering, loudness refers to the perceived level of volume of a track, and it is a critical factor in the overall sound and impact of the track. Loudness is typically measured in units called LUFS (Loudness Units relative to Full Scale), LKFS (Loudness, K-weighted, relative to Full Scale), or RMS (Root Mean Square), and these units provide a standardized way of measuring the loudness of a track, and comparing it to other tracks.
LUFS, LKFS, and RMS are all different ways of measuring loudness, and they can be used to compare the loudness of different tracks, or to ensure that a track meets the loudness standards for a particular platform or format. LUFS and LKFS are similar measures of loudness, and they are typically used for television, radio, and streaming platforms. RMS is a measure of the average loudness of a track, and it is often used for music production and mastering.
When mastering a track, it is important to consider the loudness of the track, and to ensure that it is consistent with other tracks in the genre, and meets the loudness standards for the intended platform or format. By using a loudness meter, you can measure the loudness of the track in LUFS, LKFS, or RMS, and make adjustments to the levels and dynamics of the track, to achieve the desired loudness.
Overall, loudness is a critical factor in the mastering process, and it is important to understand and control the loudness of a track, to ensure that it has the desired sound and impact. By using loudness meters and other tools, you can measure and adjust the loudness of a track, and create mixes that are consistent, professional-sounding, and ready for release.