Do sound apps use data

Is it a streaming app?

If it is, then it would be using whatever means required in order to access the internet so it can stream. You should be able to turn off "Use Cellular Data" for the app under Settings>Cellular, if you don't wish to use cellular data.

If it is not a streaming app, then it wouldn't be using the internet at all.

Cheers,

GB

Try turning off your cellular data on your Apple device (Check the cellular data usage on your iPhone and iPad - Apple Support) and running the app. If the application does not work (or does not play sound), then yes, you will be using data. I hope this answers your question!