How to create the spectrogram of many audio files efficiently with Sox?

I have a bunch of audio files and I would like to create the spectrogram for each individual file using Sox. Usually, for a single file, I do this: sox audiofile.flac -n spectrogram However I don't know how to extend this method to more than one file. Ideally I would like my output .png file to have a filename associated to its respective audio file; for example audiofile1.png for audiofile1.flac, audiofile2.png for audiofile2.flac and so on. Does anybody know how to do this?