My MacBook Startup Tone Is Missing
When a Macintosh computer powers up, you will hear a tone early in the boot cycle. This tone is known as the startup chime. It provides an audible indication that your system has reached a certain stage in the boot process. If you do not hear a startup chime on your MacBook, you will need to isolate the problem to the internal speakers or some other system component. Standard Apple computer troubleshooting procedures call for a pair of system resets that may restore the missing chime.
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Apple Startup Chime
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Since the original Apple Macintosh was introduced in 1984, Apple has included a startup chime that alerts the user when a Mac computer starts or restarts. The startup chime is a single distinctive chord on a MacBook. The chime serves as an early audible notification that the computer has passed internal diagnostic tests after the system has been booted. The chime also provides a demarcation point by which certain actions must take place, for example if you plan to boot into safe mode you must have the shift key depressed prior to hearing the chime. If you do not hear a startup chime and your MacBook does not boot up, the system requires service.
Troubleshooting MacBook Audio
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MacBooks include both internal speakers and a mini-jack for headphones or external speakers. The startup chime is designed to always play through the internal speakers. If your system boots normally and you do not hear the startup chime, test that you are able to hear sound through your MacBook's internal speakers. Disconnect any headphones and external speakers and open the Sound preference panel in your System Preferences. Select the "Sound Effects" tab and click any of the alert sounds to play them. If you hear no sounds, you may have a problem with your MacBook's internal speakers.
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Reset Parameter RAM
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Apple uses a form of memory called parameter RAM (PRAM) to store system settings when a Mac is powered off. PRAM is a form of nonvolatile RAM and may also be referred to as NVRAM. When you encounter persistent problems, such as a missing startup chime, reset your MacBook's PRAM to attempt to alleviate the problem. The standard method to reset PRAM on a Mac is to hold down four keys on the keyboard when the system starts: Command, Option, P and R. Apple advises to hold these keys simultaneously until you hear two iterations of the startup chime. If your speakers are at fault, you may not hear a chime. If you do hear a chime after holding these keys, continue to hold them until you hear a second one.
System Management Controller
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The System Management Controller (SMC) stores hardware device information in Macintosh computers. If a PRAM reset does not enable your system's chime function, proceed to reset the SMC on your MacBook. You will need to unplug the power cord and remove the battery and then hold the power button for 10 seconds. Reconnect your battery and power cord and restart the system. If you hear a chime, the SMC was at fault.
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