I wrote “roughly” on purpose, but I think your description is wrong. A compressor triggers when the signal goes above a threshold, this applies a compression fa

I wrote “roughly” on purpose, but I think your description is wrong. A compressor triggers when the signal goes above a threshold, this applies a compression factor to the loud signal, which reduces the overall gain of the loud sounds (they become quieter). That is what reduces the overall dynamic range. Making the loud sounds quieter. Most compressors then have a ‘make up’ gain control to recover the lost volume. That process makes the quieter sounds louder. Your description sounds like an expander.