Perception Lecture 7 - Test #2

Test #2

1). sound localization,

2). speech perception,

3). and musical perception

What are the three topics of auditory perception (how we experience and make sense of sound)

Distance and direction!

Our sound localization is excellent! We can localize for ___ and ___

Monaural cues

auditory cues that require input from only one ear to help us localize sound.

Intensity differences

• Differences in loudness of a sound as a function of distance

• Louder sounds → closer, softer sounds → farther

• Helps the brain localize the distance of a sound

pitch differences

for Approaching or Receding Objects (Doppler) (also help to localize distance)

Binaural cues

use both ears to determine the direction of a sound

Interaural Time Differences

difference in time it takes for a sound to arrive at one ear versus the other

About 10 microseconds

What is the absolute threshold for detecting Interaural Time Differences

Medial Superior Olive (MSO), part of the Superior Olivary Complex

Where are Interaural Time Differences (ITDs) processed in the brain?

in front or behind you (think of movie) sound is going to hit each ear the same way if in front or back of you;

• If the sound is straight in front or straight behind:

  • Time difference = 0 → sound hits both ears at the same time

  • Intensity difference = 0 → sound is equally loud in both ears

  • The brain has no difference to detect, so it can’t tell if the sound is in front or behind - Interaural Time Differences = 0

Sound localization is the toughest to locate when a sound directly

TRUE

TRUE OR FALSE: Head Movements Change Interaural Sound Reception

Cone of Confusion

• sounds produce the same timing (ITD) and intensity (IID) cues in both ears

• your brain can’t tell if the sound is in front, behind, above, or below—so localization becomes ambiguous.

Tilt your head!

How do you fix cones of confusion

Reverberations

Reflected sounds off surfaces in listening space

• Effects on sound:

  • Positive: If reflections are controlled → sound feels full and rich (like in a concert hall).

  • Negative: If too many or uncontrolled → sound becomes muddy, echoey, or vague, hard to understand.

Surround Sound Processing

create fake echoes → brain perceives depth and direction in sound

• our brain interprets these reflected sounds as 3D spatial cues, so it feels like the sound is coming from different directions.

Convincing Illusions

what is the result of surround sound processing?

They are created from surround sound processing, and its when brain interprets these reflected sounds as 3D spatial cues, so it feels like the sound is coming from different directions.

what are convincing illusions?

Language

A dynamic set of symbols of communication and the elements used to manipulate them

Functions of Language

❖To communicate (to inform and influence)

❖Guide decisions
❖Share accumulated knowledge ❖Generational transmission of knowledge

❖Provides structure to organize, share, and remember thoughts

• It is uniquely human ability

  • We are the only ones with the specialized vocal apparatus to produce speech 

Semantics

Elements which convey meaning

• The word “dog” refers to a four-legged animal (gives meaning)

Syntax

Specific rules of expression in a highly structured system

• word order (SVO)

• Sometimes called grammar

• English language subject, verb, object = most common grammatical structure

Symbolic (Displacement)

communication about things that are not physically present

• Language allows us to discuss the abstract

Generativity

Capacity for infinite expression

• We can always create now words, phrases to convey new ideas, new objects, new things in our world

• Every year the major dictionaries put out a word of the year which gained traction that year-shows how new words emerge 

Arbitrariness of Symbols

Use of non-iconic symbols

• The word “dog” doesn’t look or sound like a dog — we just agree it represents that animal.

• have no inherent connection to their meaning

• For example, the word book doesn't actually tell you book, you learn the word to associate it with the symbol 

• Only a select number of iconic symbols (MOO)

Phoneme

 individual speech sound (smallest unit of sound). English has 44 phonemes (20 vowels and 24 consonants). Other languages have 20-60 phonemes

• Morpheme

• smallest MEANINGFUL unit of language; can be prefixes, suffixes, or words

  • Example: walk = one morpheme; walked = two morphemes (because the ED changes the meaning)

  • incoming:

    1. in- → prefix → meaning “toward”

    2. come → root/base → meaning “move”

    3. -ing → suffix → meaning “action in progress”

By altering the vocal tract to allow or block airflow (mouth, tongue, lips, vocal cords).

How are phonemes produced?

auditory templete

A brain mechanism that recognizes and categorizes phonemes, so you can identify them no matter who says them.

Phonemic boundaries

no blending, but shifting

• No blending: When you hear sounds that vary gradually (like a /b/ → /p/ continuum), your brain categorizes them as either one phoneme or another, not as something in between.

• Shifting phonemic boundaries: With experience, your brain adjusts where it draws the line between two phonemes based on the language you hear.

• Think about letters B and P, categorically distinct but very similar in production. However we never hear a balancing between them, the brain automatically puts them in their own category 

• When you learn phonemes, you are learning them based upon the sound you hear in year 1 of life, if you don't hear it in that time then it is very difficult to hear it afterwards. Children lose the ability to pick up phonemic differences in other languages

place of articulation

The point in the vocal tract where airflow is obstructed (e.g., lips, teeth, tongue).

• where sound is made

• lips pressed together (p, m, b)

Manner of articulation

How the block is produced (stop, nasal, etc.)

• airflow squeezed through narrow gap → hissing sound (f, v, z, s)

Grammer

Set of rules that specify how units of language can be meaningfully combined

• Subject-verb-object most common structure

• We perceive, interpret, and produce it at a rate far beyond normal auditory processing, showing its evolutionary and cognitive importance.

• We perceive, interpret, and produce it at a rate far beyond normal auditory processing, showing its evolutionary and cognitive importance. (JUST KNOW)

Bottom up

• taking sensory information and then assembling and integrating it (acoustical information of phonemes) 

  • data driven —> brain doesn’t rely on prior knowledge, context, or expectations

Top down processing

uses models, ideas, and expectations to interpret sensory information 

• most critical in speech and sound

• like hearing a muffled word in a sentence you already know: your brain uses context and expectations to “fill in” the sounds.

Aphasia

an impairment in the ability to produce or understand language, usually caused by damage to the brain

Broca’s Area

involved in language production

involved in language comprehension

Wernicke’s area

inproducing speech (putting words together in sentences or even speaking single words)

Damage to Broca’s area leads to difficulty

comprehending speech and producing coherent speech (not easily monitoring one’s own speech to make sure it makes sense).

Damage to Wernicke’s area leads to difficulty

Broca’s area and Wernicke’s area

what are the two critical brain regions for processing and producing language.

Four Examples of Top-Down Effects

❖The McGurk Effect
❖The Phonemic Restoration Effect

❖Speech Boundaries (Segmentation)

❖Speech Perception

The McGurk Effect

❖Visual stimuli (lip movements) can influence speech perception (what you think you hear)

❖Cross-modal integration of auditory and visual stimuli

❖Occurs mostly for phonemes, not words

• Example: Seeing a mouth say “ga” but hearing “ba” → you perceive “da”.

• Shows that vision + expectation affects auditory perception.

Phonemic Restoration Effect

❖Context can fill in missing phonemes

❖We can eliminate up to half of the speech

signal with little effect on perception

❖Very common example of closure (your brain’s “fill-in-the-blank” ability)

The Kingsmen “Louie Louie” Controversy

• Why did people think the lyrics were dirty?

• What does this illustrate about speech perception?

• Recording Facts:

  • Marathon 90-min session night before → Ely sore throat, braces

  • Single overhead mic 15 ft away → muffled vocals

  • Take was basically a practice version → vocals unclear

• Urban Legend:

  • Listeners claimed “dirty lyrics” → rumor spread

  • Led to 2.5-year FBI investigation

• Key Lesson:

  • Signal was ambiguous → perception influenced by expectations

  • Top-down processing: people “heard” what they imagined; Expectation & context shaping perception; People hear what they expect or are told to hear

  • Real-world example of speech perception + top-down effects

• Quotes:

  • Kingsmen: “a listener might think he heard anything he imagined”

  • FBI: “record is unintelligible at any speed”

speech segmentation?

The process by which listeners divide continuous speech into separate words

• we as perceivers must add the speech breaks

Because we can’t segment the speech, so it sounds like one fast, continuous stream.

Why do foreign languages sound faster?

Languages don’t differ much in actual speed—they only feel faster when you can’t understand or segment them. (KNOW)

All languages are around 125 to 175 words per minute. (KNOW)

vibrating objects

Music, like all objects are produced by __ __

25 to 4200 Hz

music extends from __ Hz to __Hz

TRUE

TRUE OR FALSE: Music can be produced by ANY vibrating object, does not have to specially be an instrument.

Playing A Note
❖Resulting pitch depends upon length of vibrating body

❖Creates a fundamental frequency and accompanyingharmonics (multiples of the original frequency). ❖Different instruments produce different harmonics. ❖Produces psychological characteristic of Timbre: Character of a musical sound or voice as distinct from pitch and intensity (JUST KNOW)

Playing A Note
❖Resulting pitch depends upon length of vibrating body

❖Creates a fundamental frequency and accompanyingharmonics (multiples of the original frequency). ❖Different instruments produce different harmonics. ❖Produces psychological characteristic of Timbre: Character of a musical sound or voice as distinct from pitch and intensity (JUST KNOW)

Pitch

music, like all sound is organized by ___

length of vibrating body

• Shorter vibrating length → higher pitch (higher frequency)

• Longer vibrating length → lower pitch (lower frequency)

Pitch depends upon the

An octave is the distance between two notes where one is double the frequency, and they sound like the same note at different pitch levels.

whats an octave?

Doubling length lowers pitch by an octave, halving length raises pitch by an octave.

if you double or half the length…

semitones

the smallest step between two notes

12 semitones

all the possible pitches in one octave

Tone Height

Increases in Pitch with Increasing Frequency

• Pitch goes up when frequency increases

• Voice:

  • Whispering a low note → low frequency → low pitch

  • Singing a high note → high frequency → high pitch

Tone Chroma

Psychological Similarity of Sound Occupying Same Relative Position on Different Octaves

• Even if the pitch is higher or lower, notes with the same tone chroma sound similar in their musical identity

• example

  • Piano: C3, C4, C5

    • Frequencies are different → tone height changes

    • All are C notes → same tone chroma

Chords

Three or more notes played simultaneously

• Guitar: strum C major chord → C + E + G

• Piano: press C + E + G at the same time

• Violin/Strings: multiple players play different notes together

• Voice: 3+ singers can sing different notes at once → chord

Melody

Linear arrangement of notes played in succession

• a sequence of single notes played one after another

• Example: “Twinkle Twinkle Little Star” → the notes you sing form the melody.

Consonance

simple frequency ratios → sound harmonious; perfect fifth (3:2) is especially pleasing.

• pleasing to the ear.

Dissonance

complex frequency ratios → less pleasing to the ear.

Harmony

Individual notes, melodies, or chords played simultaneously (by multiple sources).

melody, harmony and rhythm

Music is built by the interplay of :

Rhythm

Combining notes of different durations for patterns of sounds and silence. The arrangement of sounds as you move through time.

• Example: “Clap–clap–pause–clap” over a steady 1–2–3–4 beat

tempo

speed of music (how fast fast or slow)

accent

emphasis or stressed placed on particular notes

beat

steady, repeating pulse in music

• the regular, steady timing → you can tap your foot to it

duration

how long the note lasts

Meter

regularly reoccurring group of beats into measures

These are 3 examples of gestalt principles that help fill in as a whole (

Gestalt principles[

are rules your brain uses to organize information and perceive wholes, even when parts are missing.

similarity, Proximity,and closure

what are the 3 Gestalt Principles that we will go over?

• there is 7 buy going over 3

❖Pitch

We readily differentiate and organize on the basis of pitch.

❖Timbre

Grouping based on unique sound of individual instruments

Proximity

Temporal Pattern of Notes

Completing the progression of the melody

Closure