Week 6 Flashcards
Corollary Discharge Theory
Definition: movement perception depends on three signals:
Motor, Corollary discharge, image displacement
Motor signal (MS)
signal sent to eyes to move eye muscles
Movement is perceived when ____ (an evaluation unit) receives either a ___, ____.
comparator; CDS; IDS
Corollary discharge signal (CDS)
identical copy of the motor signal
○ Informs the brain about the intentional eye movement.
Image displacement signal (IDS)
movement of image stimulating receptors across the retina.
Movement is perceived when we have either CDS or IDS. T or F
T
STS Superior Temporal Sulcus
Biological motion is processed by sts and ffa
Evidence for sts
Transcranial magnetic stimulation (TMS) applied to STS caused a decrease in ability to detect biological motion.
● Result: This temporary lesion interrupted brain functioning and decreased accuracy on the task.
Sound
Sound is the experience we have when we hear.
Physical definition of sound
● Sound is pressure changes in the air (or other medium).
● Condensation: Higher levels of local air pressure.
● Rarefaction: Decreased regions/ Lower levels of air pressure.
● Sound wave: The pattern of changes in pressure across a space.
Timbre
- “quality” of a sound
- allows us to distinguish between different musical instruments playing the same pitch at the same loudness.
Perception of timbre is influenced by
Attack: how quickly a note reaches its maximum volume after being played
- Fast attack (piano note) sounds more abrupt vs. Slow attack (bowing of a violin) sounds more gradual
Decay: How quickly the sound diminishes after the initial peak
- Guitar string (rapid decay) vs. Organ (long decay)
Different harmonics: Different instruments have different harmonic content for the same pitch
Pure tones
- Perceived as a single note without any harmonics or overtones
- Simplest form of a sound wave
Complex tones:
- A combination of multiple frequencies with various harmonics or overtones
- Give the tone its timbre
Additive Synthesis:
- Constructs complex tones by adding together pure tones at different frequencies
Signal Decomposition
Fourier Analysis: breaks down a complex waveform into a series of sine waves
that sum up to the original waveform.
Fundamental frequency
- The lowest frequency in a complex tone
- Determines the pitch of the note
Missing Fundamental Effect
- Perceived pitch: periodicity pitch; when a harmonic or the fundamental frequency is lost, the perceived pitch remains the same due to the effect of the missing fundamental.
- Consistent fundamental frequency
- The spacing of the harmonics and the repetition rate of the waveform carry the pitch information related to the fundamental frequency.
Audibility Curve
- The minimum sound pressure level that the average human ear can detect at each frequency
- Humans are most sensitive to sounds in curve dips in the 2-5 kHz range
Equal Loudness Curves:
- A set of curves that illustrate the ear’s sensitivity to different frequencies at various loudness levels
- The ear is less sensitive to very low and very high frequencies.
In the sound stimulus, greater condensation of air molecules would correspond to
higher amplitude
If a sound level meter measures 0 decibels (dB), this means no sound signal is present.
False
The decibel scale relates physical pressure in the sound wave to the psychological experience of loudness. This scale demonstrates ____________________ as we attempt to estimate the magnitude of the physical stimulus.
response compression
Perceived tone height corresponds to which of the following physical dimensions of sound?
Frequency
What physical property of the sound signal does the perception of timbre correspond to most directly?
complexity
The maximum frequency that a healthy, 20-year old person with normal hearing can detect is as high as:
20,000 Hz
Sound amplitude is related to perceived loudness of a signal. If you play different frequencies at the same amplitude (intensity), they must have the same perceived loudness.
False
Which of the ossicles is attached to the tympanic membrane?
Malleus
Amplitude
Sound pressure level that corresponds to perceived loudness (for a given frequency).
tone height
The perceptual experience of increasing pitch that happens when frequency is increased.
Frequency
umber of cycles per second in which the sound pressure repeats corresponds to perceived pitch.
