Wednesday, November 24, 2010

Listen!

I passed a kid on the campus yesterday with a tee shirt that said: "If it's too loud, you're too old."

Well, there you have it.

Yes, it's too loud. The television. The traffic. The neighbor's leaf blower. The music. The national discourse.

And I'm too old. Tending towards silence. OK, maybe Elvis singing Love Me Tender just loud enough to dance to in the kitchen. Maybe a Chopin nocturne late at night, pianissimo.

The range of audibility of the human ear can be represented as a graph of sound intensity versus frequency. The lower boundary of the range is the threshold of hearing: for example, at a frequency of 256 vibrations per second (middle-C on the musical scale), a sound must have a intensity level of about 20 decibels (the loudness of rustling leaves) to be heard at all. The upper limit of the range of audibility is the threshold of pain. At the frequency of middle-C the limit of pain has an intensity level of about 130 decibels, slightly less than the sound of a leaf blower at close range.

I like to think of the graph of human audibility as a blank canvas upon which the world paints with sound. For example, the shrill double-note of the blue jay (three-tiered in frequency, at 3000, 2000, and 1000 vibrations per second, repeated twice) and the cacophonous caw of the crow (between 1000 and 2000 vibrations per second) add dollops of color to the canvas in the mid-decibel range. The chickadee's call is more sharply defined in frequency (at about 2800 vibrations per second), but can range widely in loudness depending on the distance of the bird. The nuthatch fills in the low-decibel part of the graph with its tap-tap-tap and a loudness in a conifer forest just above the threshold of hearing. There are other natural sounds that can only be heard in the complete absence of noise: the papery shiver of beech leaves on their branches, the ethereal whir of mourning doves rising from the ground, the rattle of the seedpods of wild indigo when stirred by the wind.

A blank canvas, waiting for the delicate brushstrokes.

The seedpods of wild indigo stirred by the wind.