WASHINGTON – If beauty is in the eye of the beholder, then youth must be in the ear of the beholder.

As people age, hearing changes. A sound that could once be heard clear as a bell may ring silent as the years goes by.

Some kids even take advantage of these changes by setting ringtones on their phone that adults can’t hear.

But a diminishing range of hearing is normal says Dr. Jefferey Zolt, an audiologist with Auditory Services of Potomac and Silver Spring, Md.

“If you have ever sat next to anybody in a store or on the bus and you can hear the music coming out of their headphones even though their ears are completely plugged with it you can be sure that they are listening to that at a level that is damaging to their hearing,” says Zolt.

“Not being able to hear a 20khz tone is very normal for almost any adult.”

Absolute Quality’s AQ Hearing Test offers a variety of “mosquito sound” frequencies to test hearing.

WTOP’s Mike Murillo contributed to this report.