Spring is here and the birds are singing. It's time to get our ears in tune to identify birds by song.
Did you know that even with excellent hearing there are some bird sounds we cannot hear?
Our ears are tuned to the sounds important to humans -- our own voices, babies crying, the noises of danger -- but our sense of hearing doesn't pick up everything.
Animals are the same way. Some birds make noises higher in scale than we can hear but it's well within their own hearing range. Golden-crowned kinglets and Blackburnian warblers are famous for singing high-pitched songs that sound fainter as they rise in pitch. Some people can't hear the high notes at all.
On the opposite end of the spectrum, whales sing below our range though sometimes we can feel their sounds as vibrations when they're loud enough.
So what is our normal hearing range? It's different from person to person and the range narrows as we age. Young people hear the widest spectrum. Older adults lose hearing at the top of their range.
You can experiment with what you're able to hear at this University of Kentucky Engineering webpage. Read the instructions, then scroll down for a selection of recordings of different tones. Each recording repeats the tone at a particular Hz level. The recordings start loudly and become softer as they continue.
I discovered that my hearing range is 100 Hz up to 9000 Hz but at the far ends of the spectrum (100 and 9,000) I can only hear the tone when it's very loud. It disappears as it gets softer.
That may explain why I think golden-crowned kinglets sound fainter as they rise in pitch. I'll bet they're singing with the same loudness the whole time but as they rise in pitch they approach the upper end of my hearing range.
The strangest part of the hearing test was when I clicked on the 60Hz and 10,000Hz recordings and heard nothing! Those sounds are out there but I'll never know.(*)
Try it yourself.
(photo of a Marsh Wren singing, by Chuck Tague)
(*) p.s. See the comments for information on the quality of sound from computer speakers vs. headphones.
UPDATE, Nov 28,2012: I tried this test again with better computer speakers and discovered I can hear 12,000 Hz, but it is so high that apart from the hearing test I would mistake it for ringing in my ears and not a noise produced in the wild.