What is Timbre?

Timbre is the word we use to describe the quality of a sound beyond melody, harmony, and rhythm. Timbre is how we can distinguish between different voices over the phone or how we can tell the difference between instruments in an orchestra.

Thanks to the advent of musical technology, it’s possible to describe timbre in technical terms. The two main components of timbre are:

Envelope: how the amplitude (volume) changes over time.

• Attack: The length of the initiation of sound. Longer attacks sound like volume swells (think of string instruments) while shorter attacks sound like an impact (imagine a snare drum).
• Decay: Typically the initial attack is louder than the sustained volume. The decay measures how much time there is between these two parts of the envelope.
• Sustain: This refers to how long the sustained volume is maintained. It’s interesting to note that often the sustain sounds similar regardless of the instrument.
• Release: The amount of time it takes for the sound to diminish after the sustain ends.

Overtones: the frequency content of a sound

Although we tend to think of frequency as a specific pitch, the truth is that nearly all sounds are comprised of a collection of frequencies. The way in which the frequencies combine and cancel each other out work like a fingerprint. These combinations are so specific that it’s possible to hear the difference between two different musicians playing the same instrument! What makes this even more complex is that the overtones of a sound will change as the envelope changes and will even change depending on the surrounding area. A trumpet will sound different in a concert hall, open field, and practice room.

In theory, it’s possible to synthesize any sound given a firm understanding of it’s envelope and the overtones that are being created. Let’s try and thought experiment to see how this works.

Creating white noise

White noise is something that most people have heard at some point, whether it was from TV or radio static that wasn’t tuned to the proper channel or from a “white noise” machine that helps people sleep it’s all relatively the same sound. From a technical perspective white noise is the sound of all possible frequencies happening at the same time, but, due to the nature of sound waves, the higher frequencies tend to dominate what we hear.

How could we make that sound with just our voice?

SHHHHHHHH!

That’s all it takes, but let’s go a step further. While saying “shhh” try moving your lips, tongue, and mouth to as many different positions as you can think of. Notice how each new position causes the quality of the sound to change, that’s timbre!