My MACBOOK Pro doesn't chime (BONG) during startup anymore. How do I restore that?

Thanks. Tried and negative result. Cannot explain but it was working before and stopped about a week and a half ago. Cannot determine if resulted from update or what. I have read that the chime was indication that machine was working properly. When I didn't hear it I became concerned and I've not been able to locate the problem.

NOT SOLVED! AGGRESSIVE FINGERS......

To leroydouglas...

Oops! Okay...MACBOOK PRO, Retina, 15", Mid 2015, running macOS Mojave v. 10.14.4

Reset NVRAM/PRAM as instructed and it appears to have worked. Chime was a welcome sound. Thanks to you leroydouglas and macjack for your time, assistance and patience. Glad you're out there.