What word describes musical themes that are sounded over and over again?

Your heartbeat will be relaxed when ________ is steady. But if _________ speeds up, then the heartbeat speeds up, too, and can be scary.

While major keys sound "happy", minor keys can sound dark and scary. What word describes this?

What word describes this....Some notes played together can create musical tension that can also make the listener tense.

Different types of sounds have different emotional appeals. While some sounds have qualities that can make them scary, others are just not characteristically frightening. What word describes this?

High sounds can raise the heart rate and surprise you. Low sounds can be soothing, yet can also create suspense, or a sense of mystery. Whic words describes how high or low the sounds are?