When goats were played a recording of a ‘happy’ animal bleating, they noticed when there was a shift to ‘sad’ bleats in the recording, and vice versa
Source:
https://www.newscientist.com/article/2209218-goats-reveal-their-feelings-with-the-sound-of-distinctive-bleats/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home