CEA Mastering and Loudness Standards 1 — Questions and Answers
Question 1: What is the target integrated loudness standard specified by the EBU R 128 specification for broadcast content?
- -16 LUFS
- -23 LUFS (Correct answer)
- -14 LUFS
- -18 LUFS
Correct answer: -23 LUFS
EBU R 128 specifies a target integrated loudness of -23 LUFS (equivalent to -23 LKFS) for European broadcast delivery. This standardized loudness level prevents the 'loudness war' on broadcast by normalizing all content to a consistent perceived level.
Question 2: What does 'true peak' measurement differ from standard 'sample peak' measurement in digital mastering?
- True peak measures perceived loudness while sample peak measures instantaneous amplitude
- True peak detects intersample peaks that occur during digital-to-analog conversion and can exceed 0 dBFS, while sample peak only measures the highest discrete sample value (Correct answer)
- True peak applies A-weighting while sample peak uses flat frequency response measurement
- True peak is measured over the entire program; sample peak is measured per individual transient
Correct answer: True peak detects intersample peaks that occur during digital-to-analog conversion and can exceed 0 dBFS, while sample peak only measures the highest discrete sample value
Intersample peaks occur when the waveform reconstructed during D/A conversion exceeds the original sample values between samples, potentially exceeding 0 dBFS and causing clipping in decoders. True peak metering detects these reconstructed peaks, allowing mastering engineers to apply appropriate limiting.
Question 3: What is 'dithering' and when should it be applied in mastering?
- A stereo widening technique applied during the final mastering EQ stage
- The addition of a shaped low-level noise signal when reducing bit depth (e.g., 24-bit to 16-bit) to minimize quantization distortion artifacts (Correct answer)
- A limiting algorithm used to prevent true peak clipping above -1 dBTP
- A noise-reduction process that removes dither noise added during mixing
Correct answer: The addition of a shaped low-level noise signal when reducing bit depth (e.g., 24-bit to 16-bit) to minimize quantization distortion artifacts
Dithering adds a precisely shaped noise signal (noise shaping) before bit depth reduction to minimize audible quantization distortion. It should be applied only once at the final stage of bit depth reduction (e.g., when converting a 24-bit master to 16-bit for CD delivery). Double-dithering degrades audio quality.
Question 4: What is 'dynamic range' in the context of mastering and loudness?
- The frequency range reproduced by the mastering system from lowest bass to highest treble
- The difference between the quietest and loudest levels in a program, often expressed using PLR (Program Loudness Range) or DR rating (Correct answer)
- The ratio of wet to dry signal in the mastering reverb chain
- The available headroom between -18 dBFS nominal level and 0 dBFS clipping
Correct answer: The difference between the quietest and loudest levels in a program, often expressed using PLR (Program Loudness Range) or DR rating
Dynamic range in mastering refers to the variation in loudness within a program — the difference between the softest and loudest passages. It is quantified by PLR (Peak-to-Loudness Ratio = max true peak − integrated loudness) or the Crest Factor. The DR (Dynamic Range) database uses RMS-based measurements.
Question 5: What loudness target does Spotify use for its normalized playback level?
- -23 LUFS
- -16 LUFS
- -14 LUFS (Correct answer)
- -9 LUFS
Correct answer: -14 LUFS
Spotify normalizes playback to approximately -14 LUFS integrated loudness. Masters significantly louder than -14 LUFS are turned down on Spotify; masters quieter than -14 LUFS are turned up. Mastering to -14 LUFS ensures no loudness penalty and preserves dynamic range.
Question 6: What is the primary function of a 'brickwall limiter' in mastering?
- To compress the dynamic range throughout the entire program at a fixed ratio
- To prevent any sample or true peak from exceeding a set ceiling (typically -0.1 to -1 dBTP) without allowing any overshoot (Correct answer)
- To apply mid-side processing to widen the stereo field
- To remove DC offset introduced by analog-to-digital converters
Correct answer: To prevent any sample or true peak from exceeding a set ceiling (typically -0.1 to -1 dBTP) without allowing any overshoot
A brickwall limiter applies infinite ratio gain reduction to ensure no output peak exceeds the set ceiling. In mastering it is used as the final safety net to prevent clipping during format conversion and streaming codec processing, typically set at -0.1 to -1 dBTP true peak.
CEA Mastering and Loudness Standards 1
What is the target integrated loudness standard specified by the EBU R 128 specification for broadcast content?