Tutorial 4

Question 1

How is sound generated in an electric guitar?

Answer 1

The metal string vibrates over the pickup, which is a small coil around a magnet.
The vibration of the string alters the magnetic field which generates a small current in the coil
This is fed to an amplifier to generate a sound

Question 2

What is meant by the source filter model of voiced sounds?

Answer 2

the source is air from the lungs passing through the vocal folds at the larynx.
the filter is the modification of the sound by the vocal tract, which is the path from the larynx to the lips

Question 3

What are unvoiced sounds?

Answer 3

the vocal cords don’t vibrate
they are held close together producing turbulent air flow and a broad band sound with no harmonics

Question 4

what are the three different types of phonemes?

Answer 4

vowels, fricatives, plosives

Question 5

How do vowels relate to formants?

Answer 5

the vowel sounds can be mapped by their relative amplitudes in the first two formants

Question 6

Describe the chest register

Answer 6

used for low and medium pitches. most of the vocal fold mass vibrates and the glottis is open for a relatively short portion of the vibration cycle

Question 7

describe the head register

Answer 7

used for medium and high pitches. less of the vocal fold mass vibrates and the glottis is open for more of the vibration cycle

Question 8

what are the similarities between electric and acoustic instruments?

Answer 8

the source of sound is mechanical vibration

Question 9

what are the differences between electric and acoustic instruments?

Answer 9

in acoustic instruments, the vibration moves the air directly, or by vibrating a soundboard.
in electric instruments, the vibration is turned into an electrical signal by a pickup

Question 10

why do electric guitars have better sustain than acoustic?

Answer 10

• in acoustic guitars, the energy of vibration is transferred to the soundboard. a relatively high proportion must be transferred to provide some volume, so the sound dies away quickly.
• in electric guitars, the vibration is turned into an electrical signal by a pickup, which takes away very little energy from the vibrating string. if the body and bridge are very solid and heavy then very little energy is lost from the string, allowing prolonged vibration

Question 11

what makes an electronic instrument better than an electric or acoustic one?

Answer 11

• in electric and acoustic instruments, the waveform is generated from a physical vibration like a string
• in electronic instruments the waveform is generated directly by an electronics circuit.

Question 12

What is additive synthesis?

Answer 12

additive synthesis constructs a waveform using the Fourier principle, that any waveform can be made by adding the fundamental and a series of harmonics with suitable amplitudes.
it is very difficult in practise, with analogue circuits, since each component requires a separate oscillator circuit.