1991

  
  
  
  
Very early, RTW was concerning with finding a solution how an audio engineer can produce a constant loudness impression in a safe way independently from different program material and production conditions. To give a measure for this in form of a reference value, RTW firstly created devices with loudness display. Therefore, the loudness display of the RTW peak program meters (peakmeter or PPM) is generated by analyzing the two predominant audio signal parameters, frequency and impulse. This is done by applying physiological principles analog to the processes which take place in the human ear. The signals are run through a filter circuit which uses a special filter curve developed and optimised in compre­hensive experiments carried out at the Funkhaus Berlin. The loudness meter design is based on data generated in a number of empirical listening tests.These tests were carried out with a large group of pro audio people - tonmeisters and sound engineers - each of whom participated in a series of listening sessions.
Further information can be found in the former publication Loudness Display.