Sonograms: A sound in pictures

1 When you see a solid, single line, that is a clear melodic sound, like a whistle or a bell. The song of the Mistle Thrush or the ringing song of the Great Tit are examples of this simplest of sounds. Many of us learn things more easily if we have visual clues and cues rather than just words. The good news with bird sounds is that each one can be turned into an image. It is called a sonogram, and it plots time along the x-axis and pitch along the y-axis (see bottom of the opposite page; and below). However, at first glance, it can look like hieroglyphics, too difficult to decipher. How can some random streaks and squiggles help you understand and remember bird sounds? What you need is to know the basic rules for cracking the code: 2 Many sounds show a similar solid line, but above are fainter parallel lines, which are called harmonics. Yes, the sound is actually a combination of several layers, like a chord. When we hear a sound like that, our brains tend to focus on the bass note but the other pitches give the sound added flavour. Any trumpeting or honking noise is full of strong harmonics, such as the calls of geese and gulls; but in fact, many birds show harmonics in their calls. 3 If a sound is harsh and percussive, it shows on a sonogram as a fuzzy vertical bar. These sounds, such as the rasping screech of a Jay, have such a wide range of pitches all at the same time that we don’t hear a musical note in it, but rather as a wooden tick or rattle or similarly ‘tuneless’ sound. Many bird songs, then, contain a mix of these three types of sound, clearly visible on the sonogram. Once you understand how the look of a note affects its sound, you can then concentrate on picking out other visual clues, such as the relative pace of the notes, especially when compared with the sonograms of other birds; whether the notes form a regular or repeating pattern etc. You can also spot notes which bend upwards in pitch, or down, or both.