nsci/psyc 225 exam 3 UNC

Sound (physical definition)

Pressure changes in the air or other medium.

Sound (perceptual definition)

The experience we have when we hear.

Condensation

Increase in pressure pushes particles together.

Rarefraction

Decrease in pressure causes particles to spread out.

Frequency

How many wave peaks pass a certain point per given time.

Amplitude of a wave

The maximum displacement of the medium from its rest position.

Waveform

Timbre.

Pure tone

A tone of a single frequency (rare).

Hertz (Hz)

Unit of measurement for frequency.

Frequency is the __________ of wavelength.

Inverse.

Wavelength is to color as frequency is to:

Pitch.

Amplitude determines… (sound)

Loudness.

Tone chroma

A sound quality shared by tones that have the same octave interval.

1 hertz

1 cycle per second.

Human Hearing Range

20-20,000 Hz.

Humans hear best at

1000-5000 Hz.

Amplitude (sound definition)

The pressure difference between the atmospheric pressure and the maximum pressure of the wave.

Amplitude is measured in

Decibels (dB).

Decibel SPL formula

20 log (p/20).

20 micropascals

The reference for the expression sound-pressure level (SPL).

What are complex waves made up of?

Different frequency sine waves.

Harmonics

Whole number multiples of the fundamental frequency.

Fundamental frequency

The lowest, and usually most intense, frequency of a complex sound; most often perceived as the sound's basic pitch.

Higher harmonics

Pure tones with frequencies that are whole number multiples of the fundamental frequency.

Timbre depends on

Harmonics, attack, and delay.

What are the three main cues we use to localize sound?

Binaural cues (interaural time difference and interaural level difference), and one monaural cue (spectral).

Interaural time difference (ITD)

The difference in time between a sound arriving at one ear versus the other.

Interaural level difference (ILD)

The difference in level (intensity) between a sound arriving at one ear versus the other.

Spectral cue

The distribution of frequencies reaching the ear that are associated with specific locations of a sound.

Azimuth plane

Looks kind of like the horoptor for vision; left-right plane where binaural cues help us.

Acoustic shadow

The shadow created by the head that decreases the level of high-frequency sounds on the opposite side of the head.

Cone of confusion

A region of positions in space where all sounds produce the same time and level (intensity) differences.

Normal ears can detect a time difference of…

10 m/s.

What are the various parts of the ear?

Outer ear, middle ear, inner ear, pinna, auditory canal, tympanic membrane, malleus, incus, stapes, cochlea, semi-circular canals.

Pinna

What you see of the ear; localization of sound.

Auditory canal

The area that sound waves pass through to reach the eardrum.

Resonance

Occurs when sound waves are reflected back from the closed end of the canal.

Organ of Corti

Center part of the cochlea, containing hair cells, canals, and membranes.

Cochlea

A coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses.

Scala media

Middle tunnel of the cochlea where the receptor cells for hearing are located.

3 tunnels in the cochlea

Scala vestibuli, scala media, scala tympani.

Receptors in the cochlea

Hair cells (mechanoreceptors).

Inner and outer hair cells

The ear's transducers that convert mechanical disturbance into electrical potential.

Inner hair cells

Neurons in the organ of Corti responsible for auditory transduction.

Outer hair cells

Neurons in the organ of Corti that amplify and sharpen responses of inner hair cells.

How is loudness coded?

By the amplitude of vibrations of the basilar membrane.

Place theory of hearing

The theory that different areas of the basilar membrane respond to different frequencies.

Place coding theory of hearing

The place on the membrane where the maximum peak of the wave depends on the frequency of the wave.

Complex tones

Sounds with a mixture of frequencies.

Fourier analysis

A mathematical procedure for decomposing a complex waveform into sine waves with various frequencies and amplitudes.

Tuning curves in auditory cortex

Specific frequency that each nerve fires best to.

Motile response

A response by outer hair cells that magnifies the movements of the basilar membrane.

The motile response occurs due to the _____ hair cells and serves to ____ the movements of the basilar membrane.

Outer, amplify.

Timing code

Pitch is coded by bursts of firing within peaks of sine waves.

How is sound amplitude coded with timing code?

More action potentials occurring within each burst for frequency.

Timing code only works for __________ frequencies because of the ______________________________.

Low frequencies (up to around 100 Hz) because of the refractory period of nerve cells.

Volley principle

The theory holding that groups of auditory nerve fibers fire neural impulses in rapid succession.

Auditory pathway

SONIC MG cochlear nuclei -> superior olivary nucleus (medulla) -> inferior colliculi (midbrain) -> medial geniculate nucleus (thalamus) -> primary auditory cortex.

Tonotopic map

Representation in the auditory cortex of different sound frequencies.

McGurk Effect

An error in perception that occurs when we misperceive sounds because the audio and visual parts are mismatched.

Pure tone audiometry

A procedure used to assess hearing sensitivity at discrete frequencies.

Audiometer

Instrument to measure hearing.

Audiogram

A graphic representation of the relation of vibration frequency and the minimum sound intensity for hearing.

2 types of hearing loss

Conductive and sensorineural.

Conductive hearing loss

Hearing impairment caused by interference with sound in the external canal, middle ear, or ossicles.

Sensorineural hearing loss

Hearing loss caused by damage to the cochlea's receptor cells or to the auditory nerves.

Causes of conductive hearing loss

Excessive earwax, foreign object, rupture of ear drum, infection.

Cause of sensorineural hearing loss

Damage to sound impulse pathways from the hair cells of the inner ear to the auditory nerve.

Presbycusis

A gradual loss of sensorineural hearing that occurs as the body ages.

Tinnitus

Ringing or buzzing in the ears.

Cochlear implants

A device for converting sounds into electrical signals to stimulate the auditory nerve.

Mechanoreceptors

Sensory receptors responsible for sensing distortion in body tissues.

Proprioception

Sensation of body position and limb movement.

Kinesthesis

The system for sensing the position and movement of individual body parts.

Thermoreceptors

Respond to changes in temperature.

Nociception

Perception of pain.

What type of receptors have encapsulated nerve endings?

Mechanoreceptors.

What type of receptors have free nerve endings?

Thermo/nociceptors.

Slow adapting receptors

Merkel and Ruffini.

Rapidly adapting receptors

Meissner's corpuscles and Pacinian corpuscles.

Meissner's corpuscles

Sensitive touch receptors in the dermis.

Ruffini corpuscles

Heavy touch, pressure, joint movements, and skin stretching.

Pacinian corpuscles

Respond to deep pressure and vibration; located deep within the skin.

Merkel's disks

Pressure.

Receptive field for mechanoreceptors

The skin.

Weber's 2-point threshold of tactile acuity

When does perception switch from perceiving 2 points to perceiving 1?

Low threshold

Better acuity.

Duplex theory of texture perception

The idea that texture perception is determined by both spatial and temporal cues.

Homonculus

A rendering of the body in which each part is shown in proportion to the somatosensory cortex it occupies.

Cortical plasticity

The capacity to change cortical organization as a result of experience.

Cause of Phantom Limb Pain

Areas of the somatosensory cortex take over areas of the cortex that are no longer being used.

Exploratory procedures (EPs)

Movements of hands and fingers while identifying 3D objects by touch.

EP examples

Lateral motion, pressure, enclosure, contour following.

Active touch

Touch in which the observer actively explores an object.

Temperature that cold fibers fire best at

80 F.

Temperature that warm fibers respond best at

112 F.

Paradoxical Cold Response

Both warm and cold fibers respond to really hot stimuli.

Thermal adaptation

A decrease in the perceived intensity of a temperature as time passes.

Aristotle's illusion

With fingers crossed, one touch to different fingers feels like two touches.

Pinocchio illusion

If you rub your nose and a person in front of you's nose, you may feel your nose is long.