This new feature is available on Android and iOS, through the search engine or Google Assistant.
On Google Search or Google Assistant, it is now possible to hum a song on a smartphone to find it. It is possible to perform this type of search through the Google or Google Search applications, by clicking on the “What is this song?” Button. Or “Search for a song”. On Google Assistant, it will suffice to say “OK Google what is this song? “. Then you will have to hum the melody of the song for 10 to 15 seconds. Google will then offer a selection of likely choices.
This new feature is available in English on iOS and in around 20 languages on Android. It is based on a machine learning model that has a library of song fingerprints and is able to compare them to a simple hum, even if it is not very accurate.
Source : Google