Week 11 Lecture 1 and 2

what are the 7 main pictorial cues?

1. occlusion

2. relative height

3. familiar and relative size

4. perspective convergence

5. atmospheric perspective

6. texture gradient

7. shadows

what is occlusion?

where objects appear and disappear, called deletion and accretion.

what is the correspondence problem?

when the eyes can’t tell what order an object is with a line of objects at different distances.

colour allows you to see

what is the relationship between depth and size?

how big an object appears affects how far away it appears, and how far away it is can affect how big it is.

what are the two oculomotor depth cues?

there are two main oculomotor depth cues:

• accommodation

• binocular convergence

what are the three monocular depth cues?

there are three main cues:

• accommodation

• movement-based cues

• pictorial cues

please list four pictorial depth cues

• occlusion

• relative height

• familiar and relative size

• perspective convergence

how to achieve size constancy?

• an observer needs to consider both the size of the retinal image and the distance to the object.

S = K x (R x D)

S= apparent size of an object

K is a constant

R = size of the retinal image

D= perceived distance to the object

how does the Ames room work?

• the ames room has a corner that is much larger than the other corner, and so the apparent shape of the room looks to be rectangular or square, through the viewing peephole.

what were the three depth cues in the Holway and Boring (1941) experiment?

• Binocular Cues: Information from both eyes, specifically binocular disparity (the slight difference in images between the left and right eyes), which provides robust depth information.

• Monocular Cues: Visual information that can be seen with one eye, which in this study included motion parallax (the effect of the observer moving their head or body to judge distances) and pictorial cues (such as linear perspective, shadows, and relative size).

if a tree falls in the forest and no one is there to hear it, is there a sound?

The term “sound” is often used to refer to both the physical phenomenon (e.g. people talk about “sound waves”) and to the perceptual phenomenon.

• Physical definition: Sound is pressure changes in the air or other medium (e.g. sound waves in water).

• Perceptual definition: Sound is the experience (i.e. sensation) we have when we hear.

If a tree falls in the forest and no one is there to hear it there will be a sound in the physical sense but not in the perceptual sense.

what type of sounds have a fundamental frequency and, for these sounds, how is the fundamental frequency defined?

Complex tones are sounds that are created by combining pure tones of different frequencies (i.e. sinusoidal waves of different frequencies).

what are the two attributes of pitch?

1. tone height

2. chroma

Chroma is cyclic in that neighbouring letters of the same type (e.g. C₁ and C₂) sound similar

Conversely, tone height increase from left to right on the piano keyboard in a continuous manner.

Thus, when talking about pitch you need to be clear whether you are talking about tone height or chroma

what is timbre?

When two different instruments play the same note, they don’t sound the same

This is because, in addition to playing the fundamental frequency, each instrument plays many of the harmonics (i.e. multiples) of the fundamental frequency.

The amplitude of these harmonics will be different for different instruments…

…which makes the resultant waveform different…

…which is why different instruments sound different.

They are said to have different timbres.

what is the ‘cone of confusion’?

Any two points connected by a circumference line on the surface of this cone have the same difference in distance to the two ears.

Thus, they will have the same interaural time difference.

So binaural cues cannot be used to distinguish between the two points

how do observers determine the elevation of a sound source?

Sound coming from different elevations bounces off different parts of the pinna before entering the ear canal. (pinna is the outer, fleshy part of the ear)

when listening to a sound in a room, why do people not hear echoes?

when echoes are really near to each other, the brain quietens the extra echoes to merge and form just one.

If you hear the same sound twice with a temporal separation of 5-20ms, you will not register the second sound.

Thus, you will not hear an echo.