I don't know how often this website comes-up on these forums. But, readers may want to check-out Noise Addicts just for grins and giggles.

The site will let you test your ears to see if you can "hear like a teenager" and give back to back comparisons of 128kbs and 320kbs MP3 recordings. Choice of headphones or speakers is critical. I could hear 15kHz with Audio Technica ATH ES55 headphones but not with iGrado headphones.

Have Fun!