Sound Quality

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Sound Quality

This lesson aligns with NGSS PS4.A

Introduction

Imagine you go to a concert where a piano, guitar, and violin are all playing together. Despite having the same pitch and loudness, each instrument produces a distinct sound to your ears. How does your brain manage to differentiate between these sounds? Have you ever been told that the music you enjoy is considered noise by others? Indeed, there is a difference between music and noise. The answer lies in a concept called “timbre” or the quality of the sound. In this lesson, we will explore the concept of sound quality, and how different instruments have different sound quality.

Sound Quality

Timbre is a general term used to differentiate one sound apart from another, it is also known as sound quality. The quality of sound depends on the material through which the sound is produced.

Suppose the identical note is played with the same loudness on both a piano and violin. Even though the notes are the same, you can likely differentiate them due to the distinctive sounds each instrument produces. This distinction arises because every instrument produces several pitches, including the fundamental and several overtones.

The result of multiple pitches blending through the phenomenon of interference is called sound quality. Each instrument possesses a distinct sound quality that sets it apart from others.

Sound Quality of Different Instruments

When you attend an orchestra performance, you can hear many different kinds of instruments. The difference in sound quality among these instruments comes from the structural differences of the instrument. All musical instruments generate sound through vibrations, but the specific parts of the instrument that vibrate and the methods of producing vibration differ from one instrument to another.

Even so, all instruments can be categorized into three main families: string instruments, wind instruments, and percussion instruments.

String Instruments

Examples of string instruments include violins, guitars, and banjos. They generate sound when their strings vibrate after being plucked or bowed. Figure 1 illustrates how two different string instruments produce sounds.

Cellos and electric guitars have strings of different thicknesses. In addition, the thicker the string, the lower the pitch.

Wind Instruments

Sound is produced in a wind instrument when a vibration is created at one end of its air column. This vibration generates standing waves within the air column. Wind instruments are commonly categorized into two groups: woodwinds and brass instruments. Woodwind examples include saxophones, oboes, and recorders, while brass examples include French horns, trombones, and tubas. A woodwind instrument and a brass instrument are shown in the mentioned figure.

Percussion Instruments

Examples of percussion instruments include drums, bells, and cymbals and they generate sound when struck. These instruments come in different sizes which are used to get different pitches. In general, the larger the instrument, the lower the pitch. The mentioned figure illustrates the percussion instrument.

Summary

Sound quality is a result of multiple pitches blending through the phenomenon of interference.
Each instrument has a distinct sound quality that sets it apart from others.
String instruments generate sound when their strings vibrate after being plucked or bowed.
Wind instruments produce sound when a vibration is created at one end of its air column.
Percussion instruments generate sound when they are struck.

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