The Torah describes the robe of the High Priest: on the hem of the robe golden bells alternate with golden pomegranates. The purpose of the bells is explained in Ch. 28, v. 35: “And it shall be upon Aaron when he serves, so that its sound be heard when he comes into the sanctum before the Lord and when he goes out, that he shall not die.”
What’s up with the bells? If I did any work that required concentration, the sound of the bells would be so distracting. Can you imagine every time you shifted your feet, every time you stretched, how the bells tinkling would distract you? What was the purpose of the bells?
Before I attempt to answer this question, in 2011, one of the golden bells was discovered in Jerusalem. The golden bell that was discovered cannot be positively attributed to the High Priest’s robe, but it was probably attached to one of the priests’ robes. You can see the golden bell at https://lukechandler.wordpress.com/2016/11/04/how-did-bells-on-the-high-priests-garment-sound/.
In my research, I discovered an article by Jonathan L. Friedmann, called “The Magical Sound Priestly Bells.” Cantor Friedmann is a professor of Jewish Music History at the Academy for Jewish Religion, California (not related to my school, but it started that way). Cantor Freidmann counted the reasons that the High Priest had a robe with bells: alerting other priests to vacate the premises (specifically on Yom Kippur); announcing the High Priest’s presence before God (the Torah word for bell relates to verb “to knock”); attracting the attention of worshipers; signaling that no harm has come to the High Priest; and attuning the High Priest to his solemn duties. These interpretations, in my mind, do not invoke the death of the High Priest.
There is another reason. Gunther Plaut, Friedmann, Robert Alter, and The Jewish Study Bible all cite this reason: throughout antiquity, bells and other noisemakers were used for apotropaic magic: the scaring off of evil spirits. (I needed to look up “apotropaic.” It’s an adjective meaning “supposedly having the power to avert evil influences or bad luck.”)
Probably, they were not purely decorative; they must have a good purpose. That the bells were apotropaic is as good reason as any.