Bomba is a very rare example of a performance style in which the dancer is able to directly influence the music to which he or she is dancing. When the dancer challenges the subidor drummer’s beat, the drummer is obliged to match the dancer’s tempo. This creates a positive feedback cycle: as the pace of music quickens, the dancer must move faster, and the faster the dancer moves, the faster the drummer has to play. To keep this system from spiralling out of control, the second buleador drummer keeps a steady pace with a low beat to keep the subidor and the dancer in check.
In 1926, Walter Bradford Cannon, a student of abolitionist H. Pickering Bowditch, coined the term homeostasis to describe the same pattern of feedback regulation in the human body that exists in bomba music. Cannon was especially interested in the heart’s feedback loops (in studying one of these, he coined the term “fight or flight”). One example of homeostasis is in the regulation of blood pressure; when blood pressure rises, the “baroreceptor” in the carotid artery in the neck sends a signal to the brain. The brain then sends a signal back to the heart, causing it to beat slower. This is an example of negative feedback (-). As someone exercises, a signal from the brainstem causes the heart to beat faster to move more blood (and oxygen) through the body. This is an example of positive feedback (+).
Just like in Bomba dancing, the heart uses negative and positive feedback to regulate its own tempo. As it turns out, the tempo of music and the tempo of a beating heart are both defined using Beats Per Minute, or BPM. A higher BPM indicates a faster song, or a quicker heartbeat.
Music is actually used to adjust heart rate quite often. A study at the University of Bergen concluded that music with a lower BPM has a slowing effect on heart rate, whereas music with a higher BPM (up to 136 bpm) has a quickening effect . When people go for a jog, or workout in a gym, they often listen to music above their resting heart rate to give them motivation and energy. When they want to relax and unwind, people will play music with a slower cadence, closer to their resting heart rate.
Just as a music can adjust a person’s heart rate, with technology we can change music using our heart rate. Just like Bomba allows dancers to reverse the typical performance structure and change their own beat, the pulse of a person’s heart can be used to change the tempo of music.