You can use similar effect to steer sound waves. If you’ve been to a big concert, you’ll have seen a line array (https://dt7v1i9vyp3mf.cloudfront.net/styles/news_large/s3/imagelibrary/l/livearrays0header-JZpirgddktktLor567UI3QUHaNqbR3FR.jpg) A big column of speakers hanging. There are a few issues with them, they are hard to set up. You need to get the curve just right to get the sound to go everywhere in the stadium. If you don’t get it right, you need to lower the array, tweak it and raise it again.
Now you can use arrays like this (https://pbs.twimg.com/media/DoGT5TuXkAArs1G.jpg). No curve, no third cable required to change the angle. You can steer the sound waves in software.
Same with the subs, they used to send sound in every direction. Now you can use subs bend the subs with slight delay to cancel the sound in one direction but not the other. Makes the audience happy and doesn’t annoy the neighbours as much.
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