As a DJ prepares for a milonga, the first step is to select music appropriate for the particular group of dancers. The main general criteria for tango music selection are Danceability (audible beat and predictable rhythm), Familiarity (balanced with surprise), Variety, and Energy (the ebb and flow of which keeps the dancers in the hall and on the floor). For the moment I will address only Familiarity.
“When a musical piece is too simple, we tend not to like it, finding it trivial. When it is too complex, we tend not to like it, finding it unpredictable – we don’t perceive it to be grounded in anything familiar. Music, or any art form for that matter, has to strike the right balance between simplicity and complexity in order for us to like it. Simplicity and complexity relate to familiarity . . .” – This is Your Brain on Music by Daniel Levitin p.235
This balance between simplicity and complexity is a moving target. As we become more familiar with a piece of music, we like it better and better – up to a point – but then further familiarity leads to boredom, and we like it less and less. The passage of a piece of music from too complex to perfect to too simple varies between people and between musical selections. The job of the DJ is to select musical pieces which are neither too complex nor too simple – for the particular group of dancers who will hear it. Each of the dancers will have a different relationship to each song, but it is important that all the songs fall into the range of acceptability for all of the dancers.
In a milonga – unlike other types of dancing – there is an additional level of familiarity to accommodate. Tango dancers who dance with musicality need an enhanced level of familiarity with the music; they need to know every rhythmic nuance, to inform their musicality. Tango music has more combinations and variations of rhythms than other music, and tango dancers are expected to know all of these nuances in each song, and to create a dance which exploits all of these nuances. At the stage where most listeners are starting to get bored with a piece of music, skilled tango dancers are deepening their understanding and appreciation of the same music, and may want to hear it again and again. Tango dancers with relatively high levels of skill and experience may prefer music which has already become overly familiar to other dancers at the same milonga. They may want to dance more comfortably, knowing the music so well that they can lead moves which require more preparation, and knowing they won’t ever be caught in a sudden change of rhythm in the middle of a move.
The challenge for the DJ is in accommodating all of the dancers present.