Audio Loudness Measurement

This how-to-guide highlights the benefits of the Loudness Measurements software on the WFM and WVR series products of Tektronix.

What is Loudness?
Overall loudness of a program needs to be maintained within the listening environment. If there are significant variations between programs or between channels, the user will invariably have to reach for the remote control to change the volume to a suitable listening level. This can lead to user frustration as they have to constantly change the volume control between programs and between channels. The broadcast chain needs to maintain a suitable average loudness for the various programs they are transmitting.

Loudness is a subjective measurement and is primarily a psychological correlation with the physical intensity of the audio signal. Different people will perceive the loudness of the signal differently and therefore a variety of techniques have been used to characterize the overall loudness of the signal. The ITU-R BS.1770 standard (algorithms to measure audio program loudness and true-peak audio levels) is one method for measuring loudness within broadcast environments. This methodology use a RLB weighting curve which is a specific high pass filter defined within the standard. To configure this measurement within the waveform monitor the following steps are recommended.