Loudness normalization makes file four times larger

Question

I have several WAV files that I pass through FFMPEG's loudness normalization:

ffmpeg -i input.wav -filter:a loudnorm=I=-24:TP=-9:LRA=7 output.wav

The output files are on average four times larger (4.8 MB versus 1.2 MB, 1.8 MB versus 453 KB, etc.) Since WAV is already uncompressed, I'm surprised at this larger size.

Why are the output files many times larger?

Answer 1

Inspecting the input and output files, I realized that the output was upsampled from 48 kHz to 192 kHz. I disabled that with the option -ar 48000.