“’How do I hear with my eyes?’ Donald Kroodsma asks, and yes he has an answer. The answer is the heart of The Singing Life of Birds . . .” So began a review of my first book. The answer, of course, lies in the sonogram (also called a “sound spectrograph,” also spelled “sonagram”), what I think of as a musical score made especially for birdsong.
I have written about these sonograms in various places. In Birdsong by the Seasons, for example, I offered a section entitled “The Sonagram is a Window on the Mind of a Singing Bird.” It is in these graphs of birdsong that one can see the intricacies of what arose in the bird’s brain, cascaded down the neurons to the two voice boxes, where tiny pairs of muscles manipulated vibrating membranes in precision puffs of air, the sound finally bursting out the bill of the bird into the world. Although you can read that “Window on the Mind” section by clicking on the above link, you will need the book in hand to see and hear all of the examples provided.
Two free software programs are widely used to make these sonograms. One is from the Cornell Lab of Ornithology, called Raven-lite; a “professional version” is available, at a cost, for the serious scientist who wants to collect numbers. The other software program is Syrinx-PC, available here. Both provide a wealth of opportunities to see birdsong while you hear it, and it is the eyes and ears working together that sharpen one’s hearing.
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For Audubon Magazine, I prepared an article entitled “The Oldest Music,” a web exclusive on The Singing Life of Birds. Unfortunately the song files are no longer available at that website, so I provide the contents of the website and the sounds below.
How to Read a Sonogram (excerpted from Audubon Magazine)
The elements of a sonogram are pretty simple and straightforward. The horizontal axis is time, and the sonogram is read from left to right, just as one would expect. On the vertical axis is frequency. A typical scale runs from 0 to 8,000 cycles per second, with “cycles per second” being the number of times per second that air compresses and rarefies to produce the sound we hear. Keep in mind that at middle A on a piano, the wire vibrates at 440 cycles per second, and the highest note on a piano is a C, at 4,186 cycles per second, which is about the opening note in the first black-capped chickadee sonogram below. The sonogram is, in essence, a musical score for birdsong. (Note: In the vertical axis on the sonograms, “cycles per second” is shortened to “hertz,” named after a German physicist, and a thousand cycles per second is a kilohertz, or simply kHz. The highest note on a piano is thus about 4 kHz.)
On the sonogram, different sounds have a predictable appearance. A slammed door or a gunshot is a “noisy” sound, consisting of a complex sound spanning many frequencies, and on a sonogram this sound is a brief, vertical mark spanning several thousand cycles per second. A woodpecker drum thus consists of a series of “slamming doors,” with the bill slamming into the tree numerous times in succession, and along the sonogram’s time axis one sees many vertical marks spaced out accordingly. A pure whistle held at 4,000 cycles per second would be a horizontal line on the sonogram, much like the opening whistle of the black-capped chickadee song in the first sonogram below. Slur the whistle down the scale, and the marking on the sonogram slides down, too, as seen in the last four notes of the first towhee song.
One begins to see the possibilities—it’s that simple. Watch the sonagrams as you listen to the songs on this web site, and you’ll soon hear a whole new world of birdsong and appreciate anew the saying that “Seeing is believing.”
Black-Capped Chickadee, North American “hey-sweetie” songs.
North American Black-capped Chickadee hey-sweetie songs Sci Am Chickadee–hey sweetie
Songs of most black-capped chickadees across North America are the hey-sweetie, consisting of two main whistles, the first higher than the second; a slight pause occurs in the middle of the lower whistle, hence the two-syllable sweetie. A male often sings many renditions of this hey-sweetie song on one frequency before shifting to another, but in the above sample of nine songs hear how the fifth and seventh songs are lower than the others.
In the two sonograms, see that the first song is slightly higher in frequency than the second. Listen to these two songs, as the recording catches a male in the act of switching from a higher frequency to a lower one. As you listen, hear the hey and sweetie within each song, and hear how the pitch shifts to a lower hey-sweetie in the second song.
Black-Capped Chickadee, Martha’s Vineyard “sweetie-hey” songs.
Martha’s Vineyard Black-capped Chickadee Sci Am chickadee–MVineyard
On Martha’s Vineyard, the songs of the black-capped chickadee are different from those throughout North America. The songs on the Vineyard still consist of two main whistles, but both are on the same frequency. On the island are three different song dialects, the dialect on the western end of the island, at Gay Head, consisting of sweetie-hey songs, with the brief pause now in the first whistle, not the second.
At dawn, males alternate a low and a high version of this sweetie-hey song. In the sonagrams, see how the first sweetie-hey is lower than the second. As you listen to the songs, hear each element within the songs and how the male alternates songs at the high and low pitches.
Eastern Towhee, New England
|Eastern Towhee Sci Am towhee A B C|
Male eastern towhees in New England have several different songs in their repertoire, the three sonograms illustrated here all being from the song repertoire of one male. Each song is of the format drink-your-teeeeeee, with a couple of introductory notes (drink your) and then a series of repeated elements at the end of the song (teeeeeee).
As a male sings, he typically repeats one of his songs many times before switching to the next (unless you catch him in an energized dawn performance, when successive songs are usually different). With a little practice, each of the songs can be recognized by ear, and the switch from a series of one song to a series of the next is rather striking. See how you do in the above recordings; it begins with a chewink call, then the song program for the nine songs is A A A B C B C B C.
Bewick’s Wren, adult song
Adult Bewick’s Wren Sci Am BeWren A
Each male Bewick’s wren has a song repertoire of 15 to 20 different songs. In this particular song, see several introductory notes at the beginning and then two series of repeated elements at the end. The buzzy chatter (numbered “2”) followed by the four “S-shaped” notes (“3”) at the end of the song make this particular song distinctive. A male will repeat a song like this up to 50 times in a row before switching to another song in his repertoire.
Bewick’s Wren, juvenile song
Juvenile Bewick’s Wren Sci Am BeWren juv
A young wren, like most other songbirds, must learn his songs much like baby humans need to learn their language from adults. These sonograms show how this young wren is “babbling” as he utters a nonsensical stream of sounds much like a human child does when learning to speak. (The CD for The Singing Life of Birds provides a more extensive comparison of wren and child babbling.)
Compare, for example, the elements numbered “3” and “2” in this brief sequence for this young male and for the adult male (see above). This young male is practicing these two elements, and they will eventually match perfectly the songs of adults around him. As he practices, however, see how uncertain he is in successive attempts at the same sound (look at those two S-shaped notes), so different from the crystal clear, precisely repeated elements of the adult. See also how this young male has elements 2 and 3 reversed, but he’ll eventually reverse the order, singing all of the elements in the same order as the adults around him.
The particular song sparrow that was studied for The Singing Life of Birds had eight different songs in his repertoire. Illustrated here are sonograms of just two of those songs. See how Song A begins with three raspy notes, followed by an extended, broad-band buzzy note, then a series of repeated elements dominated by five low-frequency whistles, and finally a soft, low buzz on the end. Song G is strikingly different, as seen in the sonogram and heard when listening to these two songs.
With a little practice, all eight songs of a particular male can be easily recognized. One can then listen as a male repeats a particular song many times, eventually switching to another of the songs in his repertoire.
Eastern Winter Wren
Song at normal speed: Sci Am WiWren A
Song at 1/6th normal speed: Sci Am WiWr A 1-6 speed
The song of the eastern winter wren is extraordinarily complex, consisting of well over 100 tiny notes that this male has learned from other singing males in his neighborhood. See all of the dainty little elements sprinkled about the sonogram, this particular song easily distinguished from the other song in this male’s repertoire by the placement of the “high” and “low” series of repeated elements. As you listen, realize that the wren must hear the details of this song much better than we do or else he wouldn’t be able to imitate the precise details of the neighbors’ songs. Listen to this song at 1/6 th normal speed and you begin to appreciate how the wren might hear this song.
Even more complex is the song of the western winter wren. Western males have much larger song repertoires, and each song is far more complex. These differences in singing between eastern and western winter wrens reveal that they are really two different species (illustrated in sonograms and sounds in the book).
Eastern Wood-Pewee Sci Am EWPewee dawn
The songs of the eastern wood-pewee, like the songs of other flycatchers, are inborn, not learned as they are in songbirds like the chickadees, towhees, wrens, sparrows, thrushes, and the like. At dawn, the pewee uses three different songs, the pee-ah-wee, the wee-ooo, and the ah-di-dee, in fascinating sequences. Learn to recognize these three songs, and then find a pewee at dawn as he tells all that is on his mind. Hear him during a more leisurely daytime performance, however, and you’ll hear just two of these songs, the pee-ah-wee and the wee-ooo. (Hint: The first four songs in the above recording are pee-ah-wee, ah-di-dee, ah-di-dee, and wee-ooo.