the.EchoNest.com does analysis of music tracks and provides some very interesting information.  We’re currently using them to source some of the tempo and meter information on the music4dance site, as well as making use some of their acoustic attributes to sort songs.

Three of the acoustic attributes that EchoNest computes are of particular interest.  EchoNest calls these attributes Danceability, Energy and Valence, but we’ve relabeled them to fit more reasonably into our context.

Beat

This is the attribute that EchoNest labels “Danceability.”  Their descriptions though looks like it maps pretty closely to consistency and strength of the beat of the song.   Since we’re already using dance-ability to refer to the more specific attributes related to a dance style, we’ll refer to the attribute as beat.

Energy

EchoNest describes this attribute as “a perceptual measure of intensity and powerful activity released throughout the track. Typical energetic tracks feel fast, loud, and noisy.”  This maps directly to something that we’ve been tagging songs with manually – low, medium and high energy so we’re using this attribute directly.

Mood

EchoNest has an attribute that they call “Valence.”  They describe this as “the  musical positiveness conveyed by a track. Tracks with high valence sound more positive (e.g., happy, cheerful, euphoric), while tracks with low valence sound more negative (e.g. sad, depressed, angry).”  It seems like Mood is a more user-friendly description of this, so that’s what we’re labeling this attribute.

Currently, we’ve implemented sorting by these attributes.  So clicking on the Beat (drum), Energy (flame) or Mood (face) icon will sort the current list.  Clicking the same icon will sort by the same attribute in the other direction.  Direction of sort is indicated by an arrow on next to the icon.

Each of these attributes is a number from 0.00 to 1.00.  We’ve converted these into percentages and show an appropriately ‘filled’ icon for a song based on the EchoNest number.  So a number of 0.33 will round to 30% and the icon will be shown 30% full.  Here’s a visual on the different levels of fullness for the Energy attribute from lowest to highest.

You can also use the advanced search form to choose an attribute and direction to sort.