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Is there anything like an interactive version of aplay or speaker-test?

I'd like to be able to send simple commands on the standard input of a running program that plays simple audio (even a sine wave), and have it alter its output in response (e.g. change pitch or volume). Is there anything standard for that, or would I have to program it myself? I'm not interested in a GUI synth program or anything like that, unless it can be controlled on the fly from a pipe to stdin. (My idea is to use `mkfifo` from a Bash script and periodically `echo` to the pipe.)