Secrets To Understanding Song Patterns

A quick tutorial on sound visualization

Until you make a concerted effort to learn them, bird songs mostly go in one ear and right out the other. Since humans are such visual creatures, many people find that visualizations are the key to recognizing and remembering the unique voices of birds. Fortunately, there are tools that can visualize the properties of a sound—all you need to know is a little about how sound is produced.

Sound is a pressure wave

Fundamentally, sound is the vibration of molecules. That’s why there’s no sound in space. Here on earth, air molecules that have been set into motion by a vibrating sound source—like bird’s voice box—bump into each other. This creates a cascade of movement that we call a pressure wave because it moves outward in bands of increased air pressure. Because your eardrum is sensitive to tiny differences in pressure, you detect the airborne vibrations that enter your ear as sound.

Sound is a pressure wave

A pressure wave of air molecules visualized.

Waveforms: Seeing changes in loudness over time

Since we can’t see sound, it helps to find ways to visualize it. Waveforms waveform: for sound, a graph displaying the change in air pressure (along the y-axis) over time (along the x-axis), the higher the air pressure the louder the sound, for example, show the peaks and lulls in air pressure over time—the higher the air pressure, the louder the sound. For simple sounds we can also see differences in pitch on the waveform—with more widely separated peaks indicating a slower-moving, longer-wavelength, lower-pitch sound.

Waveforms show changes in loudness over time. Distances between peaks are used to calculate pitch.

Waveforms show changes in loudness over time. Distances between peaks are used to calculate pitch.

 

Spectrograms: Seeing changes in pitch and loudness over time

Spectrograms spectrogram: for sound, a graph displaying the changes in pitch (along the y-axis) and loudness (in color intensity) over time (along the x-axis) add another very helpful dimension to sound visualization by showing changes in pitch and loudness over time. Spectrograms can come in many colors, but typically the brighter the color, the louder the sound.

Spectrograms show changes in pitch and loudness over time

Spectrograms show changes in pitch and loudness over time.

 

Seeing the beauty in bird song

Spectrograms allow you to see song patterns at a glance. The Eastern Wood-Pewee (Contopus vireos) sings such a high-pitched whistle that it can be hard to recognize the pattern by ear—but the “M” shape it makes on a spectrogram is unforgettable.

Spectrograms can also reveal hidden complexities in bird song. The Veery (Catharus fuscescens) sings an otherworldly song that can be appreciated even more when seen on a spectrogram. When you look closely, you see that the Veery strings together pitch sweeps and mini-trills to create its impressive flutelike vocal effects.

Further Learning

Interactive: Bird Song Hero

The game that trains your brain to see sound and learn bird song.

Play Bird Song Hero >

Animated Slides: Bird Song Visualized

Animated scientific illustrations bring learning to life.

Download the Complete Set >

Free Download: Raven Lite

Make your own spectrograms with Raven Lite.

Download Raven Lite >