This song, from Saskatoon’s The Deep Dark Woods 2011 albumThe Place I Left Behind, is the sonic equivalent of simple food. Cooked with the finest ingredients and given careful attention to detail, dishes made with few ingredients can take your breath away.
There isn’t much to it. The lyrics are typical modern folk, a coming of age story and longing after an unattainable love. The structure is straightforward verse chorus verse, and the instrumentation is fairly sparse. But it all works together perfectly and precisely, especially the subtle two-way vocal harmony. And the effect is magnified because they are sung so quietly.
Why do those harmonies sound so good to our ears though? What makes one combination of notes soothing and warm and another jarring and disturbing? I was surprised to find that a name ripped from my undergraduate engineering textbooks was influential in trying to explain our appreciation of musical consonance and dissonance. Hermann von Helmholtz (of Helmholtz Equation fame and later supervisor of Heinrich Hertz) was not only a physics professor but a physician and anatomist interested the physics and physiology of musical experience, who published “On the Sensations of Tone as a Physiological Basis for the Theory of Music” (Die Lehre von den Tonempfindungen als physiologische Grundlage für die Theorie der Musik ) in 1877. In it, he proposed that the consonance or dissonance of two notes played or sung together depends on the interference pattern of the sound waves of the two notes.
When the crests (the areas of maximum air compression) in each sound wave meet each other they will be added together to create a new maximum. When a crest of one wave meets a trough (an area of minimum air compression) in the other, they will cancel each other out. The figure below shows the result of two waves of different frequencies, which we would hear as two different notes. Together they make a new combined wave that has its own rising and falling pattern. This interference pattern can be heard as beats or pulses in the combined sound.
Helmholtz proposed that the number of interference beats per second (called the beat frequency) would determine how combinations of notes sound. Combinations that create 35 beats per second would sound the most dissonant. He further noticed that among sound combinations that have similar beat frequencies, those that are further apart on the scale sound better than those that are closer together. So intervals of a fourth or fifth (say notes of C and F or C and G) tend to sound nicer than intervals that are only a semitone apart (say notes of E and F) even if they have similar beat frequencies. He coined the term roughness to describe the combined effect.
So I’m thinking it’s technically correct to say that Sugar Mama works because the harmonies are so darn smooth. Thanks Helmholtz.
The Finch and Pea 
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