Waveform Audio File Format is a Microsoft and IBM audio file format standard for storing an audio bitstream on PCs. These sd2 files contain 8 or 16-bits, mono, stereo sound data recorded in the program.
SD2 file extension is related to an audio format used by the Sound Designer 2 program for older Macintosh computers.
Audio/vnd.wave, audio/wav, audio/wave, audio/x-wav