I am deaf to high frequencies in my left ear as a result of an ear infection when I was a toddler.<p>Once this was discovered, I had a hearing test once per month for several years. This was always done by wearing headphones, then listening for tones of various frequencies. When I heard a "beep", I pressed a button. At times, white noise was included.<p>However my experience these days is that I can hear music just fine in both ears, but I cannot understand human speech in my left ear. It's not usually a problem unless you whisper into it - during normal conversation I can hear you just fine in my right.<p>This suggests to me that the way I was tested was not completely effective. Perhaps a better way would be to play recordings of speech and other sounds - not just fixed-frequency beeps - into my ears, to determine whether I understood them.<p>Consider that neurologist Oliver Sacks writes of people who hear just fine, but cannot understand speech at all. They can read and write, they can hear anything else, but their brains are unable to transform the sound into perceivable words. One such patient described speech as sounding "like the wind in the leaves of trees".