Song finder apps work by creating a digital database of musical "fingerprints," which an app sorts through to find out which song is playing. Song finder apps like Shazam are typically used on mobile devices and are used to look up musical information for songs that are playing from virtually any source. Some song finder apps can look up song information based on whistles, humming and singing.
Song finder applications create a huge catalog of digital fingerprints of songs that a software program is able to quickly organize and search through. These fingerprints are based on numerous factors of each song, such as the frequency and intensity of each section of the song. A three-dimensional graph is produced from this information, and the regions of peak intensity are noted and cataloged.
When a song is played into a song finder app, the app creates an instant fingerprint of the song based on the same principles. It then compares the new fingerprint to the database of fingerprints, searching for any that are either a match or are close to being a match. If a partial or full match is found, the application returns this information to the user. If not, the application will usually generate an error message stating that the song cannot be found.