Here is a type defined for DBPro memblocks that are created in that manner:
type dbWAVEFORMATEX
wFormat as dword
nChannels as dword
nSamplesPerSec as dword
nAvgBytesPerSec as dword
nBlockAlign as dword
wBitsPerSample as dword
cbSize as dword
endtype
The memblock contains this 28 byte header at the beginning, followed by the sound samples.
The format most often used is WAVE_FORMAT_PCM, which has a value of 1. The sound that you hear is the samples played back at the sample rate. The entire process is controlled by that header at the beginning.