SOUND & INTENSITY
Sound is a physical phenomenon that is produced when an object vibrates. The vibration is transmitted in the form of sound waves and it must travel through a “medium” such as air, water and wood. The speed of sound through air is 340 meters per second (m/s). Sound cannot travel through a vacuum because there are no particles to carry the vibrations.
Chladni plates experiment
Acoustics is the scientific study of sound. It also refers to the properties of a room that cause it to reflect, refract, and absorb sound. It is important to control how sound behaves to design spaces such as auditoriums, theaters and libraries. In an auditorium, acoustic design helps sound travel so that everyone can hear the music, while in a library acoustic design prevents sound from traveling to keep the environment quiet.
It is essential to consider the reflection, absorption and transmission of sound. When a wave reaches surfaces such as walls, floor and ceiling, part of the wave is reflected, part is absorbed and part is transmitted to the other side. There are materials that reverberate or absorb more than others, e.g. tiled floor compared to carpeted one.
Silence is the absence of sound or noise. It is an element in music that is as important as sound, because both elements are the basis of musical creation. In music, a rest is the time in which no sound is produced. Composers use rests to serve different purposes: as a contrast with sounds, as a brief pause between phrases or sections; or as the beginning or end of a musical work. Some composers such as John Cage have used silence as a major element of their pieces. For example, 4’33'' by John Cage. This piece is made up of silence during 4 minutes and 33 seconds.
John Cage - 4'33''
Anechoic chamber
"There is no such thing as silence.
Something is always happening that makes a sound."
– John Cage
Noise is usually defined as a disagreeable auditory experience, but this is a subjective definition. The difference between sound and noise is the sort of waves: sound waves are regular and noise waves are irregular.
​Noise pollution is produced when the sound gets too loud or lasts too long. It’s a very common problem in our society and can be harmful to our health.
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Some of the causes of environmental noise are: transportation, industrial and construction activities, social events, etc.
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Effects of noise on health include: hearing loss, sleep disorders, stress and aggressive behavior.
HEARING
The ear is the organ that perceives sound. Hearing is the process in which sound waves are captured by the outer ear and cause the eardrum to vibrate in the middle ear. These vibrations are turned into electrical signals and transmitted to the brain in the inner ear.
Ear parts: A outer ear, B middle ear, C inner ear; 1 pinna, 2 ear canal, 3 eardrum, 4 hammer/malleus, 5 anvil/incus, 6 stirrup/stapes, 7 Eustachian tube, 8 semicircular canals, 9 cochlea, 10 auditory nerve.
Human hearing limits
The human ear cannot detect all sounds.
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Regarding pitch, the range of human hearing normally goes from 20 to 20.000 hertz (Hz). Frequencies below the human hearing range are known as infrasounds and those above it are known as ultrasounds. But age and prolonged exposure to loud sounds can significantly lower your ability to hear high frequencies.
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Regarding intensity, the range of human hearing normally goes from 10 decibels (dB) which is the threshold of hearing to 120 decibels (dB) which is the threshold of pain.
Ear care tips​
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Don't stick cotton swabs or your nails into your ears because you can damage the ear canal, push earwax deeper into the ear and even rupture your eardrum.
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Lower the volume of video games, television and music, especially if you listen to them with in-ear earphones (those that are worn inside the ear) as they can damage your hearing as much as a chainsaw.
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Wear protective earplugs or earmuffs when you are exposed to loud noises at concerts, car races, etc.
QUALITIES OF SOUND
Every sound has four qualities: intensity, pitch, duration and timbre.
Intensity is the quality of sound that depends on the wave amplitude and allows us to distinguish between loud and soft sounds. We represent intensity in scores by means of dynamic markings.
Pitch is the quality of sound that depends on the wave frequency and allows us to distinguish between low and high sounds. We represent different pitches in scores by means of musical notes.
Duration is the quality of sound that depends on the wave persistence and allows us to distinguish between long and short sounds. We represent duration in scores by means of note values and rests.
Timbre is the quality of sound that allows us to identify the object that produces the sound (different voices and instruments). It depends on the shape of the object, the material from which it is made and the way the sound is made. The result is a complex wave composed of a fundamental frequency and its harmonics.
INTENSITY AND DYNAMICS
In music, we use the word dynamics to describe the volume of sound and we represent it in scores by means of dynamic markings. These markings are usually placed below the staff by means of Italian words, abbreviations or signs. Intensity of sound is measured in decibels but dynamic markings are relative, they don't correspond to a specific number of decibels. E.g. a fortissimo performed by a whole orchestra will be much louder than a fortissimo played by one violin.
Haydn - Symphony n. 94 'Surprise' II. Andante
Björk - It's Oh So Quiet
Types of dynamic markings
Uniform dynamic markings: These markings point out that the volume should be maintained until another marking appears to modify it. The basic markings are the Italian words piano, meaning soft, and forte, meaning loud.
We expand the range of terms by adding these modifiers:
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The prefix mezzo- means "half" or "moderately" and it lessens the effect of the term.
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The suffix -issimo means "very" and it increases the effect of the term. We can reinforce this superlative by adding -iss-, e.g. pianississimo.
In theory, it is possible to add as many p or f as one would like, but in practice we rarely find more than two or three. Some composers use these extreme dynamics. E.g. Tchaikovsky’s Pathetique symphony includes six pppppp, Holst's Mars includes four ffff and Ligeti's The Devil's Staircase goes up to eight ffffffff.
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Variable dynamic markings: These markings point out that the volume changes. The signs < and > are known as hairpins and they are as long or short as necessary to indicate how long the effect should last.
Debussy - Clair de lune
(pianissimo)
Carl Orff - Carmina Burana. O Fortuna
(fortissimo - pianissimo)
R. Strauss - Also Sprach Zarathustra
(crescendo)
Grieg - The death of Aase
(crescendo - diminuendo)
ACTIVITIES
1.1. Write the type and meaning of the following dynamic markings.
1.2. Order these dynamic markings from softest to loudest.
Mezzopiano – Fortissimo – Pianississimo – Mezzoforte – Fortississimo – Pianissimo – Piano – Forte
1.3. Sound meter task.
a) Measure 3 sounds you hear in your environment with a sound meter app and write down the result in dB.
(Sound Meter: Android or Decibel X: Android & iOS). Describe them using these adjectives:
high, low, loud, soft, long, short, pleasant, unpleasant, irritating, stressful, serene, calm.
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b) Analyze the results taking into account that the limit noise level per day accepted by
the World Health Organization (WHO) is 55-65 dB.
- Is there noise pollution in your environment?
- How can we reduce noise pollution?