David Griesinger Lexicon 100 Beaver Street Waltham, MA 02154

The study of hall acoustics continues to suffer from the difficulties of obtaining accurate measurements of halls in the presence of audience and musicians. An effective measurement technique must be fast, accurate, pleasant, and entertaining. It has become routine to measure unoccupied halls using a Maximum Length Sequence (MLS) as a stimulus. Originally chosen because MLS stimuli can be deconvolved without multiplication, there are a number of disadvantages of MLS in occupied hall measurement. Current computers provide fast and efficient deconvolution of arbitrary stimuli, which allows us to design a stimulus specifically for occupied halls. This paper will review currently available measurement methods, present MATLAB routines for generating and deconvolving effective stimuli, and show the results in occupied halls. The routines allow a complete series of binaural hall measurements with three source positions to be completed in less than 1.5 minutes while entertaining the musicians and audience. Good results can be obtained with time-variant enhancement systems, and results can be recorded with ordinary cassette recorders. A laptop computer equipped with a 16 bit sound card can be used for signal generation and analysis.