Of the Moon and My IPod

I read somewhere, I don't know where, about why a full moon appears so large on the horizon but shrinks as it climbs the sky. It is not from some refraction effect of the thicker atmosphere. It is simply because near the earth we have points of reference and the moon is large in comparison. High in the sky our only reference is the expanse of sky and the moon appears small. You can demonstrate this to yourself. When the moon is at the horizon, hold out your thumb next to it at arms length. Note how it compares to your thumbnail. Do the same thing when the moon is high. You will find they match.

I bring this up to talk about IPods. People say that IPods or other mp3 players will harm one's hearing. My personal experience tells me the opposite. Ear buds do not shut out or muffle the sound around you like earphones do. As I have walked around town listening to my IPod at a relatively constant volume a surprising number sounds drown out the sound from the IPod. Leaf blowers are loud of course, but they overwhelm my music at a hundred yards. Ordinary traffic noise is much louder than I would have thought and usually overwhelms my IPod.

An IPod is to the hemisphere of sound as a thumb at arms length is to the sky. It is a crude but good enough reference point. We don't ordinarily have reference points for sound. Nowadays, even if my tunes are at home I am much more aware of sources of loud volumes and will go out of my way to avoid them. My IPod may thus save what is left of my hearing.

- J