In physical binaural measurement, physically based procedures are used, whereas in the auditory case, human listener serve as measuring and evaluating instruments. Current applications of binaural measurement and evaluation can be found in areas such as noise control, acoustic-environment design, sound-quality assessment (for example, in speech-technology, architectural acoustics and product-sound design), and in specific measurements on telephone systems, headphones, personal hearing protectors, and hearing aids [30,305]. For some applications, scaled-up or scaled-down artificial heads are in use, for instance, for the evaluation of architectural scale models [91,92,371,373].
Since artificial heads, basically, are just a specific way of implementing a set of linear filters, one may think of other ways of realizing such filters, e.g., electronically. For many applications this adds additional degrees of freedom, as electronic filters can be controlled at will over a wide range. This idea leads to yet another category of application, as follows.