Which organization defines the algorithm for loudness measurement used in broadcast?

• A. ITU-R BS.1770
• B. EBU R128
• C. SMPTE 2067
• D. AES67

Answer: (A)

Understanding loudness measurement in broadcast begins with recognizing where the actual measurement method is defined. The standard that specifies how loudness is calculated, including the weighting (K-weighting), how to compute short-term, momentary, and integrated loudness, and how gating is applied, is ITU-R BS.1770. This algorithm provides the core method meters use to produce LUFS/LKFS values that broadcasters rely on.

European practice frequently references EBU R128, which builds on that BS.1770 algorithm and sets targets (like -23 LUFS integrated) and how to apply measurements in broadcasting, but the defining algorithm itself comes from ITU-R BS.1770. The other standards mentioned relate to different areas or applications and do not define the loudness measurement method.