I wonder if it's really just something super simple like, sound waves vibrate and loosen the soil making it easier for the roots to grow deeper and thus get more nutrients.
Interesting idea. I'm tempted to do an experiment "effects of deep bass on my kale plants".
“For this paper, the researcher played the tuba for 8 hours every night in their balcony. Plant growth remained static. The rent increased”
You will find a non-negligible number of serious gardeners who insist that speaking to your plants makes them grow better.
And one reigning King!
Talk to Your Plants, and Other Gardening Know-How I Learned from Grandma Putt - Hardcover
Baker, Jerry