A bar is a part of the music that starts with an accented beat and finishes right before the next accented beat. One bar represents a metric group. They are represented on the staff with vertical lines called bar lines. Those are placed right before each accented beat and form the basic rhythm for each dance.
A time signature is used in musical notation to specify how many beats are contained in each measure/ bar and which note value is equivalent to a beat. It is indicated with a fraction at the beginning of the staff. The denominator represents the note value, for example, a quarter( 1/4) or a half note (1/2) whereas the numerator gives us the number of beats in a measure, for example, a time signature 4/4 has four beats in a measure and each of those notes is a quarter note.
The tempo is the speed at which the music notes are played.
One thing to remember is that tempo can be represented and written in two ways with the same abbreviation BPM can mean both BARS per Minute and BEATS per Minute. Additionally, it can be noted as MPM, which is measures per minute. When it is written as bar per minute, the number will generally be smaller- 24 bars per minute. Knowing the time signature, you can easily calculate the beats per minute value by simply multiplying the bars per minute X beats in a bar. For example, in Rumba we have 24 bars per minute, and 4 beats in a bar give us 96 beats per minute tempo.
Strict tempo is used primarily in ballroom dancing. It ensures that all the songs will be played at the same speed from beginning to end, giving the dancers a peace of mind that the the tempo will remain the same. The tempi are set by the National Dance Council of America or the World Dance Council, and all competitions obey those rules.
TEMPI currently approved set by NDCA
In Part 2 we will be discussing how all of that terminology can be used in Ballroom Dancing to create more clarity in the actions and more musical dancing. Coming very soon. Stay tuned.