Lecture 6

Question 1

What are some properties of sound?

Answer 1

Sound requires a medium full of molecules to propagate
• When these molecules are forced together they have more collisions
• This results in a net movement of concentrated molecules out of the area of concentration until the average distance of the medium is restored

Question 2

Sound is generated by producing what?

Answer 2

a local concentration of molecules in a medium.
This concentration moves as a sphere of increasing diameter.
Only the disturbance is propagated frm layer to layer
Some disturbance energy is lost as heat when the molecules collide.

Question 3

Give an example of a transverse wave?

Answer 3

guitar string

Question 4

Describe longitudinal waves?

Answer 4

sound in gases and liquids is based on longitudinal waves

Question 5

What are the 3 basic components of sound?

Answer 5

frequency, intensity and time

Question 6

Describe frequency

Answer 6

Measured in cycles per second or Hz
The more cycles per second the higher the pitch sounds
High frequency waves…

Question 7

Sound waves have properties in _________ and _________.

Answer 7

time and frequency

Question 8

What kind of studies allow you to quantify changes?

Answer 8

playback studies

Question 9

When can distortions happen?

Answer 9

either in time domain or frequency domain

Question 10

What distortions can be analyzed in a cross correlational design?

Answer 10

time distortions

• No distortion results in a correlation of 1
• Any correlation less than 1 indicates a time distortion

Question 11

The results of playback studies indicates a difference spectrum. What is a difference spectrum?

Answer 11

it highlights the effects of the environment on the signal that is being produced.

Question 12

When do high frequency waves occur?

Answer 12

occur in short range communciation

Question 13

When do low frequency waves occur?

Answer 13

occur in long range communication

Question 14

Sound production involves…?

Answer 14

production and modulation of acoustical energy

coupling of vibrations to the medium

Question 15

Transmission through medium involves…?

Answer 15

impedence matching

sources of distortion

Question 16

sound reception involves…?

Answer 16

Coupling of vibrations to sound receptors

mechanical to neural transduction

Question 17

What factors affect acoustic transmission?

Answer 17

Absorption
Attenuation 
diffraction
geometric spreading
interference
reflection
refraction
reverberation
scattering

Question 18

Define absorption

Answer 18

object takes in sound energy when sound waves are encountered, as opposed to reflecting the energy. Part of the absorbed energy is transformed into heat and part is transmitted through the absorbing body.

Question 19

define attenuation

Answer 19

measure of the energy loss of sound propagation in media

Question 20

Define diffraction

Answer 20

how waves bend, or change direction, as they travel around the edges of obstacles

Question 21

define geometric spreading

Answer 21

As the sound moves away from the source, the area that the sound energy covers becomes larger and thus sound intensity decreases

Question 22

define interference

Answer 22

signals reflected from the substrate later interact with the originally transmitted signal

Question 23

define reflection

Answer 23

When sound travels in a given medium, it strikes the surface of another medium and bounces back in some other direction

Question 24

Define refraction

Answer 24

is the bending of waves when they enter a medium where their speed is different.

Question 25

define reverberation

Answer 25

multiple scattering events produce time delay in the arrival of the signal – Echo

Question 26

define scattering

Answer 26

the real part of a plane wave travelling upwards

Question 27

Define intensity

Answer 27

perceived as loudness, measured in decibels, higher the intensity of a sound, the louder it sounds

Question 28

How are frequency distortions calculated

Answer 28

by subtracting the fourier transforms of each signal’s waveform

Question 29

ability to perceive a sound depends on 2 main points?

Answer 29

biological ability to detect and register signal

Attentional preparedness to receive signal

Question 30

what is the basis of signal detection theory?

Answer 30

the relationship between physical ability and attention

Question 31

How do you quantify a receiver’s optimum strategy for detecting a stimulus especially in marginal conditions?

Answer 31

• probability distribution of a signal being present given level of noise
• costs associated with the failure to detect signal that is present versus reacting to one that is not there

Question 32

Define just noticeable difference

Answer 32

The smallest change in signal that a perceptual system can register under ideal conditions

Question 33

Define just meaningful difference

Answer 33

The amount of change the perceptual system CHOOSES to recognize as a biologically significant difference

Question 34

Define habituation

Answer 34

occurs at brain level of perception
–Signals are still being relayed from sense organs to the brain, but subcortical areas of the brain are altering level of response

Question 35

Define sensory adaptation

Answer 35

• -occurs at sensory detection level

- -sensory detectors are picking up the signal, but are no longer relaying info to brain.