Yesterday was our anniversary (#29) and in line with the increasing attention we have been paying to the multitude of birds in our yard, Jen got me (us!) a book called the "Backyard Birdsong Guide." The fascinating thing is that it includes a little machine with recordings of 176 different songs covering about 80 different birds. This makes it potentially very useful, given that even when one is observing fairly closely you often hear birds that you never see, or don't see closely enough to identify them from their markings.
I don't want to sound too much like on old fart marveling at modern wonders, but this book is something of a wonder. The playback device is about the size of an old-fashioned pencil case. It would not be possible except for digital technology. I'm also fascinated at the amount of work involved in collecting all those recordings. It's co-published by the Cornell Lab of Ornithology, so it's likely the publisher was able to call on cumulative work over the years by Cornell scientists, but still and all, that's a lot of recordings. And they are distinctive. A duck doesn't sound a bit like a sparrow. And to put it all together in a product Costco can sell for 12.99 (it's 19.77 at Amazon) is a tribute to market scale economics.