This isn't an unusual problem - no startup chime is reported by users here from time to time, and is usually somewhat inconsistent.
In most instances, the problem either self-corrects, or can be resolved by an SMC reset and PRAM reset. Try these, as follows:
To reset the SMC on an Intel mini:
-From the Apple menu, choose Shut Down (or if the computer is not responding, hold the power button until it turns off).
-Unplug all cables from the computer, including the power cord and any display cables.
-Wait at least 15 seconds.
-Plug the power cord back in, making sure the power button is not being pressed at the time.
-Then reconnect your keyboard and mouse to the computer.
-Press the power button on the back to start up your computer.
Reset PRAM
-Shut down the computer.
-Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in the next step but one.
-Turn on the computer.
-Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
-Hold the keys down until the computer restarts and you hear the startup sound for the second time.
-Release the keys.
In most instances, the problem either self-corrects, or can be resolved by an SMC reset and PRAM reset. Try these, as follows:
To reset the SMC on an Intel mini:
-From the Apple menu, choose Shut Down (or if the computer is not responding, hold the power button until it turns off).
-Unplug all cables from the computer, including the power cord and any display cables.
-Wait at least 15 seconds.
-Plug the power cord back in, making sure the power button is not being pressed at the time.
-Then reconnect your keyboard and mouse to the computer.
-Press the power button on the back to start up your computer.
Reset PRAM
-Shut down the computer.
-Locate the following keys on the keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in the next step but one.
-Turn on the computer.
-Press and hold the Command-Option-P-R keys. You must press this key combination before the gray screen appears.
-Hold the keys down until the computer restarts and you hear the startup sound for the second time.
-Release the keys.
Mac Startup Sound Lower Pitch
Mar 4, 2009 3:27 AM
Mac Startup Sound Volume
Listen to every Macintosh startup and crash chime beginning with the Macintosh 128k in 1984. Inspired by the post, Mr. Macintosh discovered turning on the startup sound is just a quick change in the system settings. Spotlight is one of the Mac's most underrated tools. Every single Mac startup sound including the Newton eMate and Twentieth Anniversary Macintosh from 1984 - 2003.