Central-planned halls are highly widespread in the historical architectures of the Western
world, such as rotundae, Christian baptisteries, and Roman tombs. In such halls, whispering
galleries, flutter echoes, and sound focusing are the acoustic phenomena mainly
investigated by scholars. Instead, modal behaviour and free path distribution are generally
less treated in literature. The present study explores the modal density at low frequencies
and the relationship with the most recurrent free path lengths in three historical nearly …