Echolocation frequency is a trade-off. High frequencies give fine resolution but attenuate quickly in air; low frequencies travel further but resolve less detail. Most insectivorous bats work between roughly 25 and 60 kilohertz, above the human ceiling of around 20 kilohertz in young adults.
Euderma maculatum calls near 9 to 12 kilohertz, comfortably audible to many listeners. The likely reason is the moths it eats. Many moths have tympanal ears tuned to the frequencies of common bat calls and take evasive action when they hear one. By calling below that tuned band, the spotted bat becomes acoustically inconspicuous to its prey, a strategy known as allotonic frequency hunting and shared with a few other moth specialists.
The cost is resolution and detection range for small targets, which fits the species' habit of foraging in open air over meadows rather than in cluttered vegetation. Its enormous ears likely help recover the weaker returning echoes. Roosting habits remain the least known part of its biology, since cliff crevice roosts are difficult to reach and survey.