Good quality Ballroom Dance Music is what makes Ballroom Dancing great. Good Ballroom Dance music influences the pace, the energy, the character and the pleasure of every Ballroom Dance. Each Ballroom Dance has its own unique music. The music should make you want to get up and dance, if it doesn't, it's not a good song for Ballroom Dancing.
Most good Ballroom Dance music is played by an orchestra, not a band with a banjo, a guitar and a fiddle. The best music is "strict tempo", has the "correct tempo" (speed), a short introduction, and a reasonable "length". The song must also musically match the "characteristics" of the specific dance. Even with all of these attributes, not all music is danceable. Sometimes it sounds really good and has all of the right attributes, but when you try to dance it, it just doesn't work. I have bought Strict Tempo Ballroom Music CDs containing 20 songs, but there were only 3 or 4 good danceable songs (in my opinion) out of the 20.
"Strict Tempo" music means that the tempo (speed) of the music does not change for the duration of the song. This is important for social dancing where the dancers may not be familiar with the music being played. It is not as important for competition music because the dancers will be familiar with the music and the choreography for the dance will accommodate the variations in tempo.
"Correct Tempo" is important because the patterns and movements in Ballroom Dancing are designed for music of a specific tempo. Ballroom Music is measured in MPMs (Measures-Per-Minute). For example, the tempo for Rumba is 28 to 30 MPM and Bolero is 22 to 25 MPM. Each unique dance has its own specific tempo by design. The music tempo of the dance has to allow for the unique movements and characteristics of that specific dance. For example, Latin Motion, Rise and Fall, Sway, Hovers, Sit Breaks, Staccato Movement, etc., etc.
The "Length" of a song can affect the enjoyment of dancing as well. Most Ballroom music is around 3 to 3 ½ minutes in length. However, the music for fast dances like Quickstep, Viennese Waltz and Samba is usually around 2 to 2 ½ minutes in length. This keeps the dancers from getting all lathered up and exhausted on just one dance. Sometimes a song has an introduction a minute long. It is aggravating for a dancer to be on the dance floor and have to wait a whole minute before starting to dance. It is also aggravating to have the music abruptly stop at the end of a song while you are dancing. There is computer software available that can be used to adjust the "tempo" of a song up or down to get in the proper range, shorten the introduction of a song and fade the ending of a song that is too long. All of these adjustments help create a danceable and enjoyable Ballroom Dance song.
There are three basic musical timings for Ballroom Dance music (2/4 time for Samba, 3/4 time for the Waltz's, and 4/4 time for almost all of the other dances). Samba and Waltz music is relativity easy to recognize. The tempo is the determining factor of the music. A Country Western Waltz, for example, has a slower tempo compared to that of a Ballroom Slow Waltz. A Viennese Waltz has almost twice the tempo of a Slow Waltz but the Viennese Waltz music is quite different. Technically, a Slow Foxtrot can be danced to almost any 4/4 time music but there is only one style that enhances the characteristics of a true Slow Foxtrot.
It is important that the music reinforces the characteristics of each particular type of dance. For example: Slow Waltz has a swooping up and down, rise and fall action; Slow Foxtrot has a very smooth, even, horizontal movement; Tango has a flat, powerful, pulsing movement; Argentine Tango has even, swishing, continuous movements with kicks; Rumba has a powerful connected feeling; Cha Cha has a fast and sassy type feeling; etc., etc. The music is a key ingredient to enjoyable Ballroom Dancing.
There are two types of Ballroom Dancing. Standardized American Style and Standardized International Style. The key word here is "Standardized". This means that you can Ballroom Dance anywhere in the world. There is a slight difference in tempo and basic movement between American style and International style with American style having more open movements. They are pretty much the same from a social point of view.
When the music plays, it should be obvious what to dance and the music should make you want to get up and dance. If you can't recognize the music as a particular type of dance, it is not good Ballroom Dance music.