Spectrum analysis and angle-of-arrival estimation methods for studying the acoustics of prehistoric rock painting sites in Finland

The article gives a full report of the sound analysis and visualization methods used for examining the acoustic characteristics of the echoes at prehistoric rock art sites in Finland. The methods developed in the University of Helsinki Music Research Laboratory are exemplified with previously unpublished data gathered mostly during the field season 2018 in the Lake District of southeastern Finland. The primary audio analysis method is multichannel impulse response measurement using a custom-designed tetrahedron microphone array and various types of excitation signals. The impulse responses are used for both analyzing the audio spectrum and angle of arrival of the echoes projected by the painted cliffs using custom-written signal analysis software.