~Chapter 11 - Lecture Section 11.1

Question 1

What is the physical description of sound?

Answer 1

Pressure changes in the air (or other physical medium, like water)

Question 2

What is the perceptual description of sound?

Answer 2

The experience of hearing. Perceptually, we experience these vibrations as a sense of hearing.

Question 3

We hear ___. First, the ___ vibrate, then the ___ vibrate, then our ___ vibrate.

Answer 3

vibrations // objects // air molecules // eardrums

Question 4

What is condensed/compressed air?

Answer 4

An object moving/vibrating causes all the air molecules directly in front to be bunched up, a bit like a snow shovel compacting the snow into itself.
This compression causes all of these air molecules to bump into these other air molecules.

Question 5

Do photons and sound/air molecules travel the same way?

Answer 5

No

Question 6

How do sound/air molecules travel?

Answer 6

They bump into each other and transfer their kinetic energy.

Question 7

The pushing out of the speakers diaphragm is then followed by a pulling inwards of the speakers diaphragm which creates a large area of space for a small number of molecules, and so this creates almost like a vacuum, where it is referred to as ___.

Answer 7

Rarefied Air/Negative Pressure

Question 8

What is Rarefied Air/Negative Pressure?

Answer 8

Rarefied Air/Negative Pressure creates an area of low-density

Question 9

When you have compressions followed by rarfraction/rarefied air, what you get are ___ of pressure where there is alternation between ___ and ___, and they propagate outwards away from the sound-source and all that kinetic energy of these air molecules bouncing off each other in a wave-form will eventually reach you ear, and it will cause vibrations on your eardrum, and this is where we get to the perceptual aspect.

Answer 9

longitudinal waves // rarified // condensed air

Question 10

What are the simplest sound-waves?

Answer 10

Pure Tones

Question 11

A Pure Tone is defined as a ___ wave.

Answer 11

sinusoidal

Question 12

The sinusoidal transition between maximum pressure and minimum pressure creates a ___.

Answer 12

Pure Tone

Question 13

If we’re making a graph for Pure Tone, and plot time on the X-axis and pressure on the y-axis, we have a Sine wave, where at the peak it represents the ___, so this is the condensation/compression of air molecules at some amplitude. At the ___ we have the lowest pressure/the rarefication of the air molecules.

Answer 13

highest pressure // bottom

Question 14

Pure Tones can vary in ___.

Answer 14

Amplitude

Question 15

What is Amplitude?

Answer 15

The difference in pressure between the highest part of the peaks and lowest part of the troughs/peaks of the wave.

Question 16

Perception of Amplitude is ___.

Answer 16

loudness

Question 17

What is a Decibel (dB)?

Answer 17

Decibel is the physical measure of sound intensity. Decibel is a measure of magnitude, and is used as the measure of Amplitude.

Question 18

What is the formula for Decibels?

Answer 18

dB = 20 × log^10(p/po this is the standard pressure) (measured in Micropascals)

Question 19

If standard pressure is ___ Micropascals, then this is referred to as the ___.

Answer 19

20 // Standard Sound Pressure Level (SPL)

Question 20

What is a benefit of the formula for Decibels?

Answer 20

Because the formula for Decibels include this logarithmic calculation the decibel measure covers a large range of sound pressures in a manageable scale and corresponds to the non-linear perception of loudness that we have

Question 21

What range of pressures can be covered by the Decibel (dB) scale?

Answer 21

There is a huge range of the Relative Amplitude going from barely audible (threshold) to giant sounds (spacecraft launch at close range) in Micropascal pressures is captured by the very manageable Decibel range of about 160.

Question 22

The range of pressures that can be covered by the Decibel (dB) scale is ___.

Answer 22

0-160

Question 23

Pure Tones can vary in ___.

Answer 23

Frequency

Question 24

How is Frequency measured?

Answer 24

In cycles per second: in Hertz (Hz)

Frequency = 1 cycle/period

Question 25

The highest Frequency has the ___ period.

Answer 25

lowest

Question 26

The lowest Frequency has the ___ period.

Answer 26

longest

Question 27

Frequency is the ___ of the period, the longer the period, the ___ the frequency.

Answer 27

inverse // lower

Question 28

Frequency is somewhat linked to the perception of Pitch, such that lower frequency sounds are often perceived as ___ pitch, and higher frequency sounds are often perceived as ___ pitch.

Answer 28

lower // higher

Question 29

Often, when we are considering the perception of Pitch, it’s useful to think about ___.

Answer 29

musical notes

Question 30

Musical notes can be described by their ___.

Answer 30

Tone Height

Question 31

What is Tone Height?

Answer 31

Tone Height is the perceptual experience of increasing pitch as sound frequency increases. It is more intricate than just low keys and higher keys on a piano

Question 32

We are able to group certain ___ together.

Answer 32

Frequencies

Question 33

On a keyboard, the notes A, B, C, D, E, F, G repeat, and notes of the same letter sound similar, they are said to have the same ___. Notes of the same letter have the same ___.

Answer 33

Tone Chroma // Tone Chroma

Question 34

With a Tone Chroma, what we appear to be keeping track of perceptually is the ___ of ___ in these notes.

Answer 34

doubling // frequencies

Question 35

The difference in frequency in A1, A2, A3, A4, ect, is that the frequency ___ as you go up each set.

Answer 35

doubles

Question 36

A1 has ___Hz frequency A2 has ___Hz frequency A3 has ___Hz frequency A4 has ___Hz frequency

Answer 36

27 ½ // 55 // 110 // 220

Question 37

The frequency doubling as you go up a set in notes is referred to as an ___.

Answer 37

Octave increase

Question 38

Musical Notes are described in ___.

Answer 38

Octaves

Question 39

What is the formula for an Octave?

Answer 39

fOctave(n) = fbase* ^2^(n)

Question 40

Notes of the same ___ have frequencies that are an ___ apart.

Answer 40

Tone Chroma // Octave

Question 41

Both ___ and ___ will affect the perception of loudness

Answer 41

Frequency // Intensity

Question 42

What is the Threshold of Feeling?

Answer 42

This is from when you stop hearing a sound and start feeling it vibrating through your body.

Question 43

Any intensity below the ___ is inaudible, and just above it is barely audible.

Answer 43

Audibility Curve/Threshold of Hearing

Question 44

What is an Equal Loudness Curves

Answer 44

Sounds that are relatively the same in dB and Hz would have an Equal Loudness

Question 45

What animals can hear higher frequencies than us?

Answer 45

Dogs, Dolphins, and Mice

Question 46

A dog whistle makes frequencies around ___Hz.

Answer 46

30,000

Question 47

Elephants have a range of hearing that goes to very ___ bands, ___ than what humans can detect, and this is referred to as ___.

Answer 47

low // lower // Subsonic Communication

Question 48

The Amplitude of a Pure Tone is mostly related to the ___.

Answer 48

perceived loudness

Question 49

The Frequency of the tone is mostly related to the ___.

Answer 49

perceived Pitch

Question 50

Pure tones are ___ tones, and realistic tones are more ___.

Answer 50

simple // complex

Question 51

The perceptual quality of sound that can be directly related to its physical nature is ___, ___, and ___.

Answer 51

Sound Quality/Timbre // Loudness // Pitch

Question 52

All the other properties of sound except for Loudness and Pitch will constitute ___.

Answer 52

Timbre

Question 53

Most of our auditory experience is of ___ tones/sounds.

Answer 53

complex

Question 54

We don’t usually hear ___ at all in our natural environment

Answer 54

Pure Tones

Question 55

A ___ is the closest thing to an instrument that makes a Pure Tone.

Answer 55

Flute

Question 56

What is Additive Synthesis?

Answer 56

The summation of multiple Pure Tones to make up Complex Tone.

Question 57

Multiple Frequencies making up Complex Tones is an example of ___.

Answer 57

Additive Synthesis

Question 58

Periodic Complex Tones such as musical notes that are played are made up of multiple ___.

Answer 58

Pure Tones

Question 59

The first tone of a Harmonic is the lowest frequency, this is referred to as the ___.

Answer 59

Fundamental/First Harmonic

Question 60

In Harmonics, the Second Harmonic is ___ times the frequency of the ___.

Answer 60

double // Fundamental

Question 61

In Harmonics, the Third Harmonic is ___ times the frequency of the ___.

Answer 61

triple // Fundamental

Question 62

In Harmonics, the Fourth Harmonic is ___ times the frequency of the ___.

Answer 62

quadruple // Fundamental

Question 63

Adding Harmonics together produces a ___ and is an example of ___.

Answer 63

Complex wave-form // Additive Synthesis

Question 64

Frequency, and the Amplitude of the Frequency produce a ___.

Answer 64

Frequency Spectra

Question 65

What is the Periodicity Pitch?

Answer 65

The perceived similarity of tones that have the Harmonics removed

Question 66

How is our auditory system able to achieve Periodicity Pitch?

Answer 66

In the Frequency spectra we see that all of the Harmonics have equal power, and creates that wave form → If we remove the Fundamental, now we only have Second, Third and Fourth Harmonics, the 200 Fundamental is removed. → The wave form between the original sound and the one that is missing the fundamental still has the same period, that is to say, the waveform is the smallest non-repeating unit. → The sound with the missing Fundamental has the same period before it repeats → What we have when we look at the frequency Spectra, we can see that the Fundamental Frequency is not only indicated by the power, but by the spacing of all of the subsequent Harmonics. → We can see in b that each of the subsequent Harmonics are spaced by 200Hz, therefore, we are able to reconstruct what the Fundamental should be.

Question 67

How is it that the same note played by different instruments sounds the same tone height, but you can clearly distinguish a guitar from a piano?

Answer 67

This is due to the power of each of the Harmonics.

Question 68

Even though the Fundamental Frequency of the G3 note is 196Hz, we can see that the pattern of Harmonics that are created in a guitar or busson or alt sax, they all have the same frequencies, but the ___ of the subsequent Harmonics is slightly different. This is the ___ of the different notes.

Answer 68

Amplitude // Timbre

Question 69

What is Attack?

Answer 69

Attack of a tone is the buildup of sound at the beginning of the tone, so that it can start quiet and get louder and vice versa.

Question 70

What is Decay?

Answer 70

Decay of a tone is the decrease in sound at end of tone. This can be very rapid or very gradual

Question 71

Piano notes have a very rapid ___. If you play a note on a piano ___ it sounds like an ___.

Answer 71

Attack // backwards // Organ

Question 72

What is a Periodic?

Answer 72

Periodic sound is a sound where the pattern of pressure changes repeats. These are the musical notes / Pure Tones we’ve been talking about

Question 73

What is an Aperiodic?

Answer 73

Aperiodic sounds is where the pattern of sound waves does not repeat (e.g. door slamming or object dropping, crunch of a leaf, ect.)

Question 74

___ sounds are what we mainly encounter outside of the time we are listening to music.

Answer 74

Aperiodic