1.1 Music and Sound Flashcards Preview

As Physics Unit 1- Dr Bebb > 1.1 Music and Sound > Flashcards

Flashcards in 1.1 Music and Sound Deck (27)
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1
Q

How is sound formed?

A

Through vibrations that require a medium to travel through.

2
Q

What wave type does sound travel as and what happens?

A

Longitudinal, otherwise known as compression waves. In which a series of compressions (regions of higher pressure than the surroundings) and rarefactions (regions of lower pressure than normal).

3
Q

What is a wavelength?

A

The distance between two successive compressions is one wavelength and the symbol is λ.

4
Q

What is the frequency?

A

The number of vibrations per second or the number of compressions passing a fixed point per second and is measured in herts (Hz).

5
Q

What equation links frequency and wavelength to wave speed?

A

c = f x λ.

Wave speed = frequency x wavelength.

6
Q

What is infrasound?

A

Sound below 20 Hz is below human capabilities of hearing and known as infrasound.

7
Q

What is ultrasound?

A

Sound above 20 kHz is above human capabilities of hearing and known as ultrasound.

8
Q

When sounds are turned into an electrical signal, with a detector such as a microphone, how can the frequency be measured?

A

Using an oscilloscope. From the time-base setting the period (the time for one vibration, T) can be measured and hence the frequency (f) can be found using the equation. Period = 1/frequency

9
Q

What is the time-base of an oscilloscope?

A

This is a circuit which controls how long it takes for the trace to cross the screen horizontally.

10
Q

How is the pitch of sound from a musical instrument produced?

A

From the fundamental frequency plus harmonics.

11
Q

What is a harmonic?

A

Multiples of the fundamental frequency.

12
Q

What are sound waves of certain pitches that make a pleasant sound together known as?

A

Consonant or harmonics.

13
Q

What do consonants/harmonic sound waves form the pass of?

A

Musical interval.

14
Q

What is a musical interval?

A

An interval between two notes on a musical scale determined by the ratio of the frequencies of the notes.

15
Q

What is quality sometimes called?

A

Timbre- it is an important factor that gives a musical instrument or voice its unique character.

16
Q

What three aspects is the timbre of a sound made up of?

A

The harmonics present, the attack and decay of the sound and the vibrato.

17
Q

How can harmonics be analysed?

A

Using Fourier analysis- this characterises the wave in terms of the different amplitudes of the frequencies that make up the harmonics of the sound wave.

18
Q

How can harmonics be synthesised electronically?

A

Fourier synthesis- this is a process by which any regular sound can be reproduced by adding regular alternating voltages together.

19
Q

What is the attack of sound?

A

A measure of how quickly it reaches its peak amplitude or loudness.

20
Q

What is the decay of sound?

A

A measure of how long it takes to die away.

21
Q

What is vibrato?

A

A periodic change in the pitch of the waveform as the sound continues to be produced.

22
Q

What is a tremolo?

A

A name to describe a periodic change in amplitude- musicians will often do this deliberately to give expression or variation to music.

23
Q

Middle C has a frequency of 256 Hz. What are the frequencies of the Cs which are one and two octaves higher than middle C?

A

512 Hz and 1024 Hz.

24
Q

Define octave.

A

Musical interval between harmonics that have frequency f and 2f. Doubling/ halving of frequency.

25
Q

Define period.

A

Time for one complete cycle.

26
Q

State what is meant by the threshold of hearing.

A

Minimum intensity which can be detected by normal human ear.

27
Q

A sound source emits a continuous tone at a constant frequency.
An observer, walking at a constant speed from the source to a wall, hears a regular rise and fall in the intensity of the sound.
Explain how the minima of intensity occur.

A

Standing waves formed as a result of superposition.
Two waves, opposite directions.
They are permanently out of phase and destructively interfere.