Combine WAV files using FFmpeg
ffmpeg -i input1.wav -i input2.wav -i input3.wav \
-filter_complex '[0:0][1:0][2:0]concat=n=4:v=0:a=1[out]' \
-map '[out]' output.wav
ffmpeg -i input1.wav -i input2.wav -i input3.wav \
-filter_complex '[0:0][1:0][2:0]concat=n=4:v=0:a=1[out]' \
-map '[out]' output.wav