This article seeks to recapture the sensory experiences of prehistoric hunter-gatherers in the Finnish Lake District by examining the acoustics of their rock art sites. The sites consist of vertical cliffs rising directly from the lakes, with painted images of humans, boats, and animals, sometimes also drummers (5000–1500 calBC). The acoustic impulse response measurements performed at 37 sites indicate that the painted cliffs, in their original state, reflected sound more strongly and accurately than the nearby lakeshore rocks. The psychoacoustic criterion and the auralizations created through artistic improvisations indicate that the reflections generated discrete single-repeat echoes, which endowed sounds produced in front of the cliffs with their auditory mirror images. As these reflections appeared to emanate from invisible sources behind the paintings, the auditory and visual images overlapped merging into one multisensory experience. Although the sounds and music of prehistoric people are beyond our reach, the study shows that the physical environment actively participated in their activities, co-vibrating and creating reciprocal tangible encounters between the human and more-than-human worlds. For the history of sound and music, the study provides an example of how significant a role sound reflections could have in past societies.