Abstract: A bass drum comprises a batter head and a resonant head at opposite ends of a cylindrical shell, wherein the resonant head is excitable to produce a lower resonant pitch than what is typically achieved with conventional bass drums. In some embodiments, the resonant head includes the cone of a conventional speaker. The speaker cone, however, is driven by fluid dynamics rather than by electromagnetic force. Moreover, the speaker cone can function without relying on any active electrical pickup coil or transducer being attached to it. In preferred embodiments, the speaker cone is part of a speaker assembly that has an outside diameter that is appreciably smaller than the inside diameter of the shell, wherein an adaptor ring bridges the radial gap between the speaker assembly and the shell. The adaptor ring is particularly useful in retrofitting standard size drum shells with standard size speaker assemblies.