"The timbre of his voice went into that low register that made my insides curl in on themselves—it was like my uterus was tapping out a happy dance on the rest of my organs." ~Cora Carmack, Losing It
"Timbre" is a rather difficult-to-define yet hard-to-ignore concept. When it comes to musical timbre, I have described it before as the color of sound. It's the quality of the sound we hear that helps us differentiate between a flute, a violin, and a tuba.
Our perception of timbre is informed in large part by the acoustical qualities of a sound—the type of attack, the decay, the shape of the waveform that creates the pitch. These are combined and work together to create a sound that is unique to that instrument, to the song, and even to that particular performer.
Much of the research on timbre has explored the acoustical qualities that contribute to timbral perception. For example, there are consistent attempts to quantify ways in which different sounds are perceived as different through identifying the qualities that make a sound unique (e.g. the slight "thump" and damp sound that ends a harpsichord sound). There are spectral qualities that influence our perception of timbre and temporal qualities. And to add to the complexity of timbre perception, individuals differ in how much they rely on the spectral and temporal qualities (McAdams & Giordano, 2009).
In other words, there is no one way to perceive timbre.
Other researchers have started exploring the neural mechanisms underlying timbre processing. For example, researchers at Johns Hopkins University developed a computerized mathematical model that would simulate how the brain processes timbre. Their particular model correctly identified an instrument based on its timbral qualities 98.7% of the time.
Why this interest in timbre? As a music therapist, understanding timbre informs my research and clinical work through its connection to emotions. I consider the music-emotion connection to be one of the primary mechanisms underlying why music therapy works. Music therapists learn to manipulate timbre as a way to connect with clients, influence them emotionally, grab their attention, and help them sustain their focus. Timbre can help build and release tension (McAdams & Giordano, 2009), it can impact emotional expressions and perceptions (Gabrielsson & Lindström, 2010; Juslin & Timmers, 2010), and it can even be manipulated with our youngest clients as we are born with a capability to perceive timbre (Trehub, 2003).
Although my understanding of timbre is from a music-biased perspective, it would not surprise me if understanding timbre processing translates to non-musical sounds as well. The timbre of a baby laughing compared with the timbre of a baby crying elicits completely different emotional responses. Same with the color of a kitten purring verses that of a lion roaring. And what about choosing what type of voice you prefer your GPS be set to? I imagine there's a reason some prefer the deep British-sounding male voice over the higher, Siri-sounding female voice (and vice versa).
So why take an interest in understanding timbre? It seems to me it goes beyond pure scholarly and scientific reasons. Our quest to understand timbre may be part of a larger exploration in understanding and making sense of the colors of all the sounds we live around.
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Gabrielsson, A. & Lindström, E. (2010). The role of structure in the musical expression of emotions. In P. Juslin & J. Sloboda (Eds.), Handbook of music and emotion: Theory, research, applications (pp. 367-400). Oxford: Oxford University Press.
Juslin, P. N. & Timmers, R. (2010). Expression and communication of emotion in music performance. In P. Juslin & J. Sloboda (Eds.), Handbook of music and emotion: Theory, research, applications (pp. 453-489). Oxford: Oxford University Press.
McAdams, S. & Giordano, B. L. (2009). The perception of musical timbre. In S. Hallam, I. Cross, & M. Thaut (Eds.) The Oxford handbook of music psychology (pp. 72-80). Oxford: Oxford University Press.