The acoustic measurements indicate that the studied sacred sites have a distinct acoustic character. Steep and rocky canyon lakes give rise to several echoes, especially in the summer. Throughout the year, the strongest and most pronounced echoes are reflected from the painted or sacrificial cliffs, which, in addition to true echoes, are reflective enough to create flutter-type echoes, auditory illusions as well as phantom sound sources. These results, together with previously unnoticed drumming figures in the Värikallio painting, provide a clue to the significance of the sound rituals at the sacred sites. This type of acoustics would have offered favourable prerequisites for ritual communications with the cliffs or with the spirits thought to dwell within them.