Unknown song stuck in your head? Hum it to Google.

Search for a song when you only know the tune.

If you've ever had a song stuck in your head but didn't know the words or the artist, you know it can be an all-consuming mission to name that tune.

You're hard-pressed to search for it when all you know is the chorus goes something like, "Hmmm, hmm, hmm-hmmm, dunnnn..." Yeah, that's not searchable.

But as of Thursday, Google added a "hum to search" feature on its mobile apps. At its virtual Search On event highlighting updates to its search engine, Google execs showed how a few seconds of humming or whistling could turn up real results.

On an iOS or Android device, you can use the Google app, Search widget, or Google Assistant and ask, "What's this song?" and start humming. There's also a "Search a song" button, so click that and then start humming.

The Google app can detect the song just by its melody — no lyrics or pitch-perfect singing required. I tried it out with a Spice Girls hit through the Google app on an iPhone, and it came back with the correct result.

Many years ago, song detector apps like SoundHound could also identify a song from a few seconds of humming or off-tune singing. But these days, if you open Shazam or a similar audio detection app and hum, say, "Barbie Girl" by Aqua (it was a 1997 classic), it doesn't bring up any results.