Coure summary

Question 1

What element of the string affects the frequency?

Answer 1

thickness

Question 2

how is sound produced in a wind instrument?

Answer 2

vibration in wind instruments is caused by some mechanism converting the linear flow of air from the player’s breath into a period motion which produces the standing waves in the pipe

Question 3

what are the two oscillators which normally make up wind instruments?

Answer 3

lip+mouthpiece and the instrument itself

Question 4

Why do hammered instruments have a high volume?

Answer 4

due to mechanism of the hammers and the very large soundboard

Question 5

why do hammered instruments have very good dynamic range?

Answer 5

velocity sensitive nature of the keys / hammers

Question 6

Can a hammered instrument bend notes?

Answer 6

no, it is fixed on a chromatic scale

Question 7

How does a whistle produce sound?

Answer 7

flow of air directed over fipple, where the turbulent motion of the air causes a vibration to be set up

Question 8

Why are wind instruments capable of high volume?

Answer 8

they move air directly rather than relying on transmission to a soundboard

Question 9

How do formants relate to singing?

Answer 9

in singing, formants define the unique sound of a singer’s voice, and a strong formant in the 2-3kHz range is important for opera singers, as it is the range they tend to be weak

Question 10

what are the three classes of percussion instruments?

Answer 10

chordophones, membranophones, idiophones

Question 11

describe a membranophone

Answer 11

does not have harmonic series, produce high volumes due to the large volume of air they move, large dynamic range since they can be struck with a large range of forces and implements

Question 12

describe an idiophone

Answer 12

solid vibrating material struck directly

Question 13

describe subtractive synthesis

Answer 13

• fundamental sounds are based on sawtooth or square waves, which already contain a rich combination of Fourier components (harmonics) which can be filtered or amplified to modify the sound

Question 14

describe digital signal processing

Answer 14

signals are generated and processed by algorithms

Question 15

how does a loudspeaker work?

Answer 15

small, changing current in the coil generates a magnetic field.
this interacts with field of permanent magnet
this causes a force between the coil and magnet, which in turn makes the cone vibrate, which generates sound

Question 16

explain analogue recording

Answer 16

• the sound is sampled continuously and converted to a signal which can have any value between some limits
• this is converted into a quantity that can be stored on a mechanical or magnetic medium

Question 17

explain digital recording

Answer 17

• sound is sampled periodically at a high rate, and converted from a signal into a number which can only have discreet values between some limits
• the number is converted to binary, where it can be represented by 0s and 1s, which are easy to store in mechanical or magnetic format

Question 18

describe the disadvantages and advantages of digital and analogue recording

Answer 18

advantages:
- digital communication has noise immunity
^after the initial digitalisation of the sound (x1) all subsequent stages are perfectly reproduced and the signal is converted back to analogue sound for hearing (x2)

disadvantages:
- in audio, each stage of an analogue recording and playback system introduces more noise on top of the original signal