Chapter 11 Sound, Auditory system, and Pitch perception

Question 1

Sound (physical)

Answer 1

Pressure in the air or other medium

Question 2

Sound (perceptual)

Answer 2

Experience we have when we hear

Question 3

• Condensation
• Refraction

Answer 3

• When surrounding air molecules are pushed together, increasing the air pressure
• When air molecules spread out, filling in the increased space = decreased air presure.

Question 4

Sound wave

Answer 4

Pattern of pressure change in a medium.
Air: 340m/s
Water: 1,500m/s

Question 5

How do sound waves travel?

Answer 5

The air molecules move back and forth, but stay in the same place. Analogous to ripples in water when a pebble is dropped.

Question 6

Pure tone

Answer 6

A sound wave that is characterized by a sine wave pattern of pressure change.

Question 7

Amplitude

Answer 7

Size of the pressure change

Question 8

Frequency

Answer 8

Number of times per second that the pressure changes repeat.

Question 9

Decibel (dB)

Answer 9

Unit of sound indicating the presence of a tone relative a reference pressure.
dB = 20 log (p/po)
(p): pressure of the tone (stimulus)
(po): reference pressure (usually set at 20 micropascal)

Question 10

SPL (sound pressure level)
ex. 20 dB SPL

Answer 10

Indicates we have a standard pressure (po) of 20 micropascals

Question 11

Level/Sound level

Answer 11

Refers to decibels or sound pressure of a sound stimulus

Question 13

What perception of sound is frequency associated with?

Answer 13

Pitch. Higher frequency = higher pitch

Question 14

Frequency is indicated in what units?

Answer 14

Hertz. 1 Hz = 1 cycle per second

Question 15

Fundamental frequency

Answer 15

First harmonic (lowest frequency) of a complex tone

Question 16

Periodic tone

Answer 16

The properity of sound waves to repeat (pure tones, complex tones)

Question 17

Additive synthesis

Answer 17

Technique for building a complex tone in which a number of sine waves (pure tones) are added together. Fundamental frequency (ex. 200 Hz) is added with another pure tone that is a multiple of the fundamental (ex. 200Hz +200Hz = 400Hz).

Question 18

Harmonics

Answer 18

Additional tones added too the fundamental frequency during additive synthesis.

Question 19

Loudness

Answer 19

Quality of sound related to amplitude or sound pressure. Also referred to as the level of an auditory stimulus. dB is often associated with loudness.

Question 20

Decibel vs. Loudness

Answer 20

Decibel is a physical measure.
Loudness is psychological

Question 21

Pitch

Answer 21

The attribute of auditory sensation in terms of which sounds may be ordered on a musical scale. Perceptual quality we describe as “high” or “low”. Closely related to frequency.

Question 22

Tone height

Answer 22

The increase in pitch due to the frequency being increased.

Question 23

Tone chroma

Answer 23

Perceptual similarity of notes seperated by octaves.

Question 24

Octave

Answer 24

Tones that have frequencies that are binary multiples of each other. ex. 800Hz is one octave above 400Hz.

Question 25

How is pitch determined?

Answer 25

By information that indicates the fundamental frequency (ie. spacing of harmonics, repetition rate of waveform), NOT b/c of its presence.

Question 26

Effect of the missing fundamental

Answer 26

When the fundamental or other harmonics are removed but does not change the tones pitch. Produces a periodicity pitch.

Question 27

Periodicity pitch

Answer 27

A pitch that maintains its tone when some harmonics are removed.

Question 28

Range of hearing

Answer 28

Specific range of frequencies in which sound can be heard.

Question 29

Audibility curve

Answer 29

Indicates the threshold for hearing by comparing free-field presentation (listening to loud speaker) vs. frequency.

Question 30

What is our range of hearing?
What frequencies are we most sensitive too?

Answer 30

20Hz - 20,000Hz
-Most sensitive between 2,000Hz - 4,000Hz.

Question 31

Auditory repsonse area

Answer 31

Light green area above the audibility curve. We can hear sounds within this area.

Question 32

How do we determine the loudness of a tone?

Answer 32

By knowing its dB level and its frequency

Question 33

Equal loudness curves

Answer 33

Tones that create the same perception of loudness at different frequencies.

Question 34

Timbre

Answer 34

Another perceptual quality of tones; Distinguishes between two tones that have the same loudness, pitch, and duration, but still sound different.

Question 35

Attack

Answer 35

The buildup of sound at the beginning of the tone.