By Michael Pilhofer, Holly Day

There are many things that musicians need to take into account when trying to achieve the best sound. One thing that music theory indicates is important is tone color. The tone color, or character, of an instrument is made up of three basic components:

  • Attack

  • Timbre (or harmonic content)

  • Decay

These three factors are what make every instrument sound different.

Attack: Checking out the beginning sound of a note

The attack is the very first sound you notice when you hear a note, and it’s possibly the most distinguishing aspect of a note played by an instrument. The violin, piano, and guitar all have their own distinctive attacks. Here’s a brief rundown of each:

  • Violin: When you hear the first microsecond of a violin being played, you instantly know it’s a violin because of that quick, raw sound of a bow being drawn across the familiar‐sounding string. It’s beautiful, immediate, and unmistakable. You don’t even know you’re hearing the first tiny point of contact, but it’s there. If you were to slow down a recording of any virtuoso’s violin solo, you would find that gorgeous, familiar rasp at the beginning of every bow stroke.

  • Piano: Each time you hit the key of a piano, a tiny hammer strikes three metal strings simultaneously, producing a beautiful, ringing attack. It’s even more amazing to open up a piano and listen to how each note sounds when the frontpiece or lid isn’t muffling the sound.

  • Guitar: The guitar’s distinctive attack is a sharp little twang when the metal strings are first plucked. However, the sound is definitely less pronounced when the guitar has nylon strings. The different types of strings are partly responsible for the variety of guitar‐playing styles by musicians. Rock, pop, and country songs are usually played with metal‐strung guitars because the metal strings provide a nice, crisp, aggressive‐sounding twang. Classical, flamenco, and much of folk music use nylon‐strung guitars because the attack is much softer‐sounding.

The speed of an instrument’s attack can play just as big a role in the sound of an instrument.

Timbre: Hearing the body of a note

The timbre (pronounced tam‐ber), or harmonic content, of an instrument is what determines the middle part, or body, of each played note. When you remove the attack and the decay of some instruments’ sounds with digital equipment, you find a lot of surprising similarities between instruments.

For example, the timbre and pitch range of a flute and violin are almost identical, but because one is blown and one is bowed, the initial attack of each separate note is completely different and identifies these instruments by their very first split‐second sounds.

However, the harmonics — or sound waves — between some instruments are radically different, simply because of their construction. For example, the harmonic content between a note on a guitar and the same note on a piano is completely different.

Any sound, no matter the source, is caused by something vibrating. Without vibration, sound doesn’t exist. These vibrations cause the air particles next to the source to vibrate as well, and those air particles, in turn, cause the particles next to them to vibrate, and so on and so on, creating a sound wave.

Just like a wave in water, the farther out the sound wave moves, the weaker it gets, until it completely dissipates. If the original vibration creates a strong enough wave, though, it eventually reaches your ears and registers as a sound.

You hear sounds because air vibrates against your eardrums, causing them to vibrate. These vibrations are then analyzed by your brain and registered as music, traffic, birds singing — whatever. Because sound waves are picked up by each unique eardrum and dissected by each unique brain, chances are that nobody hears the same sound exactly the same as anybody else.

Each complete vibration of a sound wave is called a cycle. The number of cycles completed in one second is called the frequency of the vibration. One of the most noticeable differences between two sounds is the difference in pitch; the frequency of a sound determines its pitch. Frequency is measured in hertz, with one hertz (Hz) being one cycle per second. One thousand hertz is called a kilohertz and is written as 1 kHz. A high‐frequency vibration ­produces a high‐pitched note; a low‐frequency vibration gives a low‐pitched note.

The human hearing range (audible range) is about 16Hz to 16 kHz. The frequencies of notes that can be played on a piano range from 27.5 Hz to just over 4 kHz.

Instruments get their specific sounds because their sounds come from many different tones all sounding together at different frequencies. A single note played on a piano, for example, actually consists of several tones all sounding together at slightly different frequencies. The musical note produced by a tuning fork is called a pure tone because it consists of one tone sounding at just one frequency.

Decay: Listening for the final sound of a note

Decay is the final part of an instrument’s played note. Here are the two types of instrument decay:

  • Impulsive: An impulsive decay belongs to instruments that need to be played continuously, or in pulses, in order to continue sounding. Tones are produced and immediately begin to decay until the next note played starts the process again. Common examples of instruments with an impulsive decay are those produced by plucking or striking, such as the guitar, most percussion instruments, and the piano.

  • Sustained: A sustained decay is one for which the vibrating column of an instrument, such as the body of a flute, clarinet, or other column‐shaped instrument, is excited continuously so that the sound continues in a more or less steady state as long as the note is being played. Instruments producing sustained tones are those that are bowed or blown, such as violins and other bowed stringed instruments, woodwinds, free‐reed instruments such as the accordion, and brass instruments.