Chapter 24 –Sound 24.3 –Sound, Perception and Music pp

24.3 Sound perception and music When you hear a sound, the nerves in your ear respond to more than 15,000 different frequencies at once. When you hear a sound, the nerves in your ear respond to more than 15,000 different frequencies at once. The brain makes sense of complex sound because the ear separates the sound into different frequencies. The brain makes sense of complex sound because the ear separates the sound into different frequencies.

24.3 Sound perception and music A frequency spectrum shows the amplitudes of different frequencies present in a sound. A frequency spectrum shows the amplitudes of different frequencies present in a sound.

24.3 Sonograms More information is found in a sonogram which combines three sound variables: More information is found in a sonogram which combines three sound variables: 1.frequency, 2.time, and 3.amplitude (loudness).

24.3 Sonograms Which letter represents a soft sound lasting 5 seconds? What is it’s frequency?

24.3 How we hear sound The parts of the ear work together: The parts of the ear work together: 1.When the eardrum vibrates, three small bones transmit the vibrations to the cochlea. 2.The vibrations make waves inside the cochlea, which vibrates nerves in the spiral. 3.Each part of the spiral is sensitive to a different frequency.

24.3 Sound protection Listening to loud sounds for a long time causes the hairs on the nerves in the cochlea to weaken or break off resulting in permanent damage. Listening to loud sounds for a long time causes the hairs on the nerves in the cochlea to weaken or break off resulting in permanent damage.

NOISE POLLUTION When noise reaches a level that causes pain or damages the body it is called When noise reaches a level that causes pain or damages the body it is called noise pollution. Noise pollution can damage. Noise pollution can damage the inner ear, causing permanent hearing loss. Noise pollution can contribute to Noise pollution can contribute to sleeplessness, high blood pressure and stress.

WHITE NOISE (like white light is a mixture of all colors). This is an equal mixture of all frequencies (like white light is a mixture of all colors). White noise machines are used. White noise machines are used to calm people and help make them sleep.

24.3 Music The pitch of a sound is how high or low we hear its frequency. The pitch of a sound is how high or low we hear its frequency. Rhythm is a regular time pattern in a series of sounds. Rhythm is a regular time pattern in a series of sounds. Music is a combination of sound and rhythm that we find pleasant. Music is a combination of sound and rhythm that we find pleasant.

24.3 The musical scale Most of the music you listen to is created from a pattern of frequencies called a musical scale. Most of the music you listen to is created from a pattern of frequencies called a musical scale.

24.3 Music and notes Each frequency in the scale is called a note. Each frequency in the scale is called a note. The C major musical scale that starts on the note C (262 Hz). The C major musical scale that starts on the note C (262 Hz).

24.3 Music and harmony Harmony is the study of how sounds work together to create effects desired by the composer. Harmony is the study of how sounds work together to create effects desired by the composer. The tense, dramatic sound track of a horror movie is a vital part of the audience’s experience. The tense, dramatic sound track of a horror movie is a vital part of the audience’s experience. Harmony is based on the frequency relationships of the musical scale. Harmony is based on the frequency relationships of the musical scale.

24.3 Superposition The superposition principle states that when sound waves occur at the same time they combine to make a complex wave. The superposition principle states that when sound waves occur at the same time they combine to make a complex wave. When two frequencies of sound are not exactly equal in value, the loudness of the total sound seems to oscillate or beat. When two frequencies of sound are not exactly equal in value, the loudness of the total sound seems to oscillate or beat.

24.3 Music and harmony When we hear more than one frequency of sound and the combination sounds pleasant, we call it consonance. When we hear more than one frequency of sound and the combination sounds pleasant, we call it consonance. When the combination sounds unsettling, we call it dissonance. When the combination sounds unsettling, we call it dissonance.

24.3 Making sounds The human voice is complex sound that starts in the larynx, at the top of your windpipe. The human voice is complex sound that starts in the larynx, at the top of your windpipe. The sound is changed by passing over by expandable folds (vocal cords) and through openings in the throat and mouth. The sound is changed by passing over by expandable folds (vocal cords) and through openings in the throat and mouth.

3 MAIN FAMILIES OF INSTRUMENTS String instruments String instruments Wind instruments Wind instruments Percussion instruments Percussion instruments

24.3 Making sounds For a guitar in standard tuning, the heaviest string has a natural frequency of 82 Hz and the lightest a frequency of 330 Hz. For a guitar in standard tuning, the heaviest string has a natural frequency of 82 Hz and the lightest a frequency of 330 Hz. Tightening a string raises its natural frequency and loosening lowers it. Tightening a string raises its natural frequency and loosening lowers it.

WIND INSTRUMENTS 2 types of wind instruments: 2 types of wind instruments: –Woodwind –Brass

WIND INSTRUMENTS How wind instruments produce sound:. How wind instruments produce sound: a vibration is created at one end of its air column, and then the vibration creates standing waves in the air column.

PERCUSSION How they make sounds: How they make sounds: They produce sound when they are struck

24.3 Harmonics and music The same note sounds different when played on different instruments. The same note sounds different when played on different instruments. Suppose you compare the note C (262 Hz) played on a guitar and the same note played on a piano. Suppose you compare the note C (262 Hz) played on a guitar and the same note played on a piano. The variation comes from the harmonics in complex sound. The variation comes from the harmonics in complex sound. A single C note from a grand piano might include 20 or more different harmonics. A single C note from a grand piano might include 20 or more different harmonics.

24.3 Harmonics and music A tuning fork is a useful tool for tuning an instrument because it produces a single frequency A tuning fork is a useful tool for tuning an instrument because it produces a single frequency