Plants feed off carbon dioxide. Hence, it’s not the sound of your wonderful voice, but your exhale that helps them.
Nevertheless, it appears this kind of attribution to plants is as old as the hills and part of pagan beliefs. It seems to be a fundamental of anthropology and theorized to be how people attempt to figure out and survive in the world around them when there is no benefit of education - as in paleolithic times.
Lots on this subject in the Golden Bough by Frazer. Will help you understand the lunacy of eco freaks.
Fruser....well "Professor", It is true that CO2 fuels plant growth, but the rest of the comment ignores the article's discussion of Music, sound, and plant growth.
Additional information on music and plant growth.
https://pistilsnursery.com/blogs/journal/music-and-plant-growth-heres-what-the-science-says
Snip. ..."What Botanists Have to Say"
"Devendra Vanol of the Institute of Integrated Study and Research in Biotechnology and Allied Sciences in India found that not only does music promote plant growth, but it seems that plants can actually distinguish between different types of sound including different genres of music, nature sounds, and traffic noise. Vanol and her team say it could be advantageous for plants to distinguish sounds to learn about their surrounding environment. More studies need to be done to understand how this works and what this could teach us about plants.
According to Reda Hassanien of China Agricultural University in Beijing, sound waves significantly increased the yield of sweet pepper, cucumber, tomato, spinach, cotton, rice, and wheat. Additionally, pests such as spider mites, aphids, gray mold, late blight, and virus diseases of tomatoes decreased in greenhouse conditions with sound treatment. It is amazing what plants can do with a little bit of music playing in the greenhouse!"
(Diana...maybe put an old radio in the greenhouse set it to the local PBS Classical station! (Are they still in business? Do you get FM from Madison?))