How do different musical instruments produce sound?
The voice as an instrument
Long before guitars and pianos, there was the human voice. Singing goes far back in human history – as early as the Egyptians, the Greeks, and the Romans. And, though not everyone is blessed with a golden voice, most of us would’ve made our first attempts at singing as toddlers, mimicking the nursery rhymes we were taught.
The voice as an instrument varies in range and quality depending on several factors. Sound is created through vibrations that travel through our windpipes and vocal cords, so the pitch we create is greatly affected by our anatomy – including the shape and size of our mouth.
As children, our smaller larynxes and thinner, shorter vocal cords produce higher-pitched sounds. This changes during puberty, when our voice deepens, and then again in old age, when we revert back to a higher pitch.
Our vocal range is also partially determined by our physical characteristics. The average human has a range of two to three octaves depending on their level of vocal training. That said, we have outliers like singer Mariah Carey, who is famous for her five-octave range.
A range of vocal styles and skills
The human voice is highly versatile. Just as there are innumerable sound patterns across different languages around the globe, there are also many ways in which we can manipulate and control our voice in music.
In opera, singers use a technique called vibrato, partly to add flavor and partly to ensure that their voice carries through to the end of the opera house. This involves tightening and loosening the vocal cords so that the resulting sound fluctuates between two pitches very close to each other.
Outside the opera house, we see performers making percussive sounds through beatboxing, mimicking jazz instrumentation while scat singing, or fusing rhymes with rhythm when rapping. Genres like punk and death metal involve scream-singing, which seems easy for an untrained listener but requires skill and practice to protect one’s vocal cords. Other musical traditions have their own distinct singing styles as well, like yodeling in the Alps, throat singing in Mongolia, and ululation in some African countries.
Blowing through the wind
Most musicians classify the voice as a wind instrument because we produce sound using air from the lungs. However, all other wind instruments belong to either woodwind or brass families.
Woodwind instruments usually have a tubular body through which air moves. The length of the air column influences the resulting pitch. A longer column allows for longer sound waves, associated with a lower pitch. Shortening the air column limits the length of sound waves, resulting in a higher pitch.
With many such instruments, the musician’s fingers alter the pitch by covering keys or holes found along the tube. Something we find in many woodwind instruments is a strip of material, usually made of wood or metal, called a reed. With reeded instruments, sound waves come from the vibrations produced by blowing through the reed.
Woodwind instruments
Initially made out of hollow reeds, flutes are now mostly made of plastic or metal. They create high-pitched tones. Their shorter cousin, the piccolo, produces even higher-pitched tones, but with a narrower range of sound. Since they’re just half the size of a flute, a piccolo is even more limited in terms of the lengths of sound waves it can create.
Clarinets feature heavily in orchestras since they produce a clear, bright sound suitable for melodies. They aren’t to be mistaken for oboes, which look similar but sound more nasally.
This difference in sound is primarily due to their construction. The clarinet is a single-reed instrument, the oboe is double-reed. With the clarinet, the air coming from the musician’s mouth vibrates against the mouthpiece to produce a sound. With the oboe, the two reeds vibrate against each other to create sound.
Though made of metal, saxophones also produce music through a reed and are thus considered woodwind instruments. Their dynamic and flexible sound make them popular in jazz music and marching bands.
Bold as brass
Whereas woodwind instruments rely on a reed to produce sound, brass instruments rely on vibrations that come directly from a musician’s mouth. The player holds their lips tightly against the mouthpiece, blowing air through to create a buzz which travels through the instrument’s air column. This vibration resonates through the body before it emerges as sound at the other end, also called the ‘bell.’
With brass instruments, controlling one’s breathing is crucial. Musicians alter loudness and pitch by the force of their breath and the positioning of their lips. A slower breath out produces a lower pitch, for example. In addition, some instruments have valves, which provide access to a wider range of pitches when adjusted. The trombone is unique in that it uses a slide, which lowers the pitch when extended.
Because of their construction, brass instruments can produce sounds much louder than most instruments. They can be heard from far away and are a mainstay in marching bands for this reason. Historically, trumpets have been used during wartime and hunting. Other popular brass instruments include the French horn, the trombone, and the tuba.
From ritual to battle without missing a beat
Among the oldest group of musical instruments humans would have used is the family of percussion instruments. History shows us how important drums are in the African tradition. Drums were used for religious ceremonies, and were considered sacred because they symbolized protection for royalty. Outside of rituals, drums were used to send messages to neighboring towns.
Across the world, drums have also been widely used in battle. The steady pulse kept soldiers marching and motivated while the thunderous beat intimidated the opposing side, warning them of impending danger.
Drawing its name from the Latin word meaning ‘to strike forcibly,’ percussion instruments encompass anything that creates music when struck, shaken, or scraped against something else. A baby rattle can be used as percussion. So can a baby’s tiny hands when they clap to a rhythm, or a toddler’s stomping feet – as long as they do it with enough rhythm.
How do percussion instruments work?
At its most basic, a drum is just a hollow body, usually a cylinder, with a piece of skin or other material tightly stretched over it. Striking its top produces vibrations that carry through to its interior. This chain reaction results in sound waves that reach our ears.
Percussion instruments can be either pitched or unpitched. For example, cymbals and gongs are unpitched because they have no definite pitch and do not require tuning.
Rather than contributing to the melody or harmony of a song, these instruments are used to provide a sense of rhythm. In contrast, xylophones and marimbas are pitched. The length of their wooden bars or keys determines the pitch created. As such, they support a song’s melody and harmony in addition to the rhythm.
Though some percussion instruments may seem deceptively simple to operate, playing these instruments skillfully requires a good sense of rhythm. Anyone who hopes to play a full drum kit as part of a band also needs good motor skills and coordination.
Drummers may go unnoticed performing behind their kits, but they play a crucial role as the band’s timekeeper. Percussionists set the vibe and energy of a band and can spell the difference between a good performance and a bad one.
Playing on the (harp) strings
String instruments use different lengths and thicknesses of string to produce sound. Players pluck, strum, or draw a bow across an instrument’s strings to make them vibrate.
These vibrations create sound waves that reach our ears as music. The pitch produced depends on the thickness, length, and tightness of the instrument’s strings. Thicker strings vibrate more slowly, resulting in lower frequencies and thus lower pitches. Shorter strings contain less material, and as such produce higher pitches. Pressing down on a string along a guitar’s neck effectively ‘shortens’ the string, creating a higher pitch.
Under this family of instruments, we find the guitar, violin, viola, cello, and double bass. The harp transports us to an ethereal ambiance, though if we were feeling a bit bluesy, we could pick up the banjo or the ukulele. Elsewhere across the globe, Russia has the balalaika, India has its sitar, and China has the guzheng.
A controversial half-member of this family is the piano, which straddles the line between a string and a percussion instrument. Pianos produce sound when their strings vibrate, but what sets off these vibrations is a percussive motion – pressing on a piano key triggers a mechanism in which a piano hammer strikes its corresponding string.
That music sounds electric!
Unlike wind, string, and percussion instruments, electronic musical instruments do not produce sounds conventionally, with physical vibrations. Instead, they produce and transmit signals electronically that are then converted into music.
Some electronic musical instruments serve as alternative versions of analog instruments. A keyboard works like a regular piano, except it makes sound using electricity. Many keyboards offer the added functionality of a synthesizer, which adds patterns, filters, and other effects to the music created. Likewise, the electric guitar is played through strumming or plucking, but its vibrations are amplified, and musicians can add effects to the final sound.
The theremin has the distinction of being the first musical instrument to be played without touch. It uses a magnetic field to detect the player’s hand movements. On one side, a vertical antenna adjusts the pitch created. On the other, a loop antenna controls the loudness. The instrument may come across as an oddity to some, but since its invention in the 1920s, it has been used for sci-fi movie soundtracks and pop songs alike, as in The Beach Boys’ “Good Vibrations.”
Hitting several notes with one pluck
With wind and string instruments, hitting one note involves more than just one note. Say we pluck a guitar at A2. The guitar string vibrates at 110 Hz, and we perceive the resulting sound waves as A2.
Besides vibrating as its entire length at 110 Hz, the string also vibrates as two halves of its length, at a frequency twice as fast, 220 Hz. This secondary vibration produces another tone one octave higher, A3. We call this A3 a ‘harmonic’ or an ‘overtone.’ It’s essentially the same note – an A – just higher in pitch.
Strings can also divide themselves into thirds, quarters, or fifths, producing overtones other than A. The resulting frequencies are no longer multiples of 110 Hz, and thus aren’t considered harmonic.
Given all the notes created by one pluck of a guitar string, how do we still perceive the sound as originally intended, as A2? The fundamental frequency, A2, produces a much louder sound than the secondary tones. Overtones add flavor to the overall sound, but fundamentally, what we hear above the noise is still the original A2 that was plucked.
Why do instruments sound different?
When we play the note C4 on a piano, why does it sound different from the C4 on a guitar or a clarinet? Why can we identify the same pitch as being played on a piano and not a guitar? Shouldn’t both sounds reach our ears as exactly the same?
The reason why musicians can distinguish between sounds coming from two different instruments is because of a quality called ‘timbre,’ pronounced TAM-bər, unlike the ‘timber’ one yells out when chopping down a tree.
Instruments differ in construction and material, resulting in different sets of frequencies when a single note is played. Timbre refers to the overall sound quality of a musical instrument as a result of the different overtones the instrument produces. Since different instruments produce different sets of frequencies, they don’t all sound alike, even when the same note is being played.
When we say an oboe sounds nasally, an electric guitar sounds distorted, or a tuba has a deep, rich sound, we’re referring to these instruments’ timbres. Different instruments have different mechanisms for creating sound, especially across instrument families. This affects their sound quality.
Instruments in the same family vary in size and shape, and might even be made from slightly different materials. These variations contribute to the array of sounds produced by the different instruments.
