I believe this setting is default "clear sound"..... if you use the option below "my call sound settings" : "personalize call sound", it runs a test to find the best setting for you. Depending on the outcome of the test, it gives you options to make a change to the setting. It shows a graph on wich ear hears better and you can change for optimization for the left or right ear. I dont think there is much of a change personally. I just leave it on the default "clear". Im assuming that somone with impaired hearing would benefit form this more than somone that doesnt have a hearing impairment....try the test and make a choice....or leave it default and loose nothing from your current setting....