https://www.cnet.com/news/hear-both-yanny-and-laurel-with-this-online-tool/

The tool, found here, takes the controversial clip and applies frequency filters to it, emphasizing the lower frequencies on the Laurel end and the higher frequencies on the Yanny end, making it easier to hear both. The origin of the clip itself is a poor recording of a roboticized pronunciation guide for the word "laurel" from vocabulary.com.

There are overlapping scientific explanations for the phenomenon, including the hearing range of individuals, the poor quality of the original recording, and the frequency reproduction ranges of different types of speakers and headphones.