Complex sentence: Although it is clear that the chances of hearing the sound perfectly decrease markedly with aging, there are many reports of people as old as 50 who allegedly hear the sound of the ringtone as clearly as their younger counterparts.
Split into simpler sentences: Although it is clear that the chances of hearing perfectly the sound decrease markedly with aging. There are many reports of people aged as old as 50 who allegedly hear the sound of the ringtone as clearly as their younger counterparts.