Sincere Warning: The following hearing exercise will play ultra-high-pitched sounds that most adults over 40 simply can not hear.  The sound will be similar to that of a dog whistle, and, therefore, should NOT be done with either animals or children present.  Each pitch will last for 5 seconds and, in all seriousness, should NOT be done repeatedly or at excessive volume.  To set the proper volume level, it is important that you initially adjust your speakers based on the first "10 Khz" sound so that the resulting tone is comfortably audible.  You will then be ready to proceed with the progressively higher pitches.

 One at a time, press the green play button next to each ultra-high-pitch frequency to proceed.  Press again to make it immediately stop.  (Works best with Internet Explorer.)