Week 5B – Sound, the Ear and Auditory Perception

A set of vocabulary flashcards covering sound physics, ear anatomy, sensory transduction, and auditory perception concepts from the lecture.

Frequency

The characteristic of a sound wave measured in Hertz ($Hz$), which corresponds to the perceptual attribute of pitch.

Amplitude

The intensity of a sound wave, measured in decibels ($dB$), which maps to the perceptual attribute of loudness.

Complexity

The physical characteristic of a sound wave that determines its timbre, or sound quality.

Hertz (Hz)

The unit of measurement for frequency, representing the number of sound waves per second.

Decibels (dB)

The unit of measurement used to express the amplitude or intensity of a sound.

Timbre

The quality of a sound that allows a listener to distinguish between different instruments, such as a piano and a flute, even when they play the same pitch.

Pitch

The perceptual phenomenon that depends primarily on the frequency of the sound wave.

Loudness

The perceptual phenomenon that depends primarily on the amplitude or intensity of the sound wave.

Compression

The phase of a sound wave where air molecules are pushed together, resulting in high pressure.

Rarefaction

The phase of a sound wave where air molecules are spread apart, resulting in low pressure.

Fundamental frequency

The wavelength of the longest component in a complex wave which determines the perceived pitch of the sound.

Harmonics

The components of a complex sound wave that determine its timbre or sound quality.

Fourier Analysis

The process of breaking down a complex wave into its fundamental frequency and harmonics.

Ossicles

The three small bones of the middle ear, consisting of the malleus, incus, and stapes.

Cochlea

The snail-shaped structure in the inner ear where the process of auditory transduction occurs.

Basilar membrane

A structure within the cochlea that vibrates in response to sound and contains the organ of Corti.

Organ of Corti

The structure in the cochlea that contains hair cells which detect vibrations in the basilar membrane.

Hair cells

The receptors for hearing that change their firing rate when they are bent by vibrations.

Tonotopic

The organizational principle where hair cells and neurons respond preferentially to specific frequencies, maintained from the cochlea to the primary auditory cortex.

Transduction

The process of converting environmental stimuli into neural signals; in hearing, this involves air pressure changes becoming neural firing.

Vestibular system

The system in the inner ear, including the semicircular canals, that is responsible for balance.

Vestibular-ocular reflex

The mechanism that allows the eyes to stay focused on an object while the head is moving.

Endolymph

The fluid contained within the semicircular canals of the vestibular system.

Cupula

A structure within the vestibular system involved in sensing movement and the illusion of turning.

Threshold of hearing

The lowest intensity level, typically defined as $0\,dB$, at which a human can detect a sound.

Equal loudness curve

A graph showing that low frequency sounds must be more intense than mid-range frequencies to be perceived as equally loud.

Monaural cues

Space perception cues, such as loudness and the Doppler effect, that are available even when using only one ear.

Binaural cues

Space perception cues, such as interaural intensity and time differences, that require both ears to perceive direction.

Head shadow effect

The attenuation of sound as it travels around the head to the far ear, resulting in interaural intensity differences.

Interaural time differences

The small lag in time, up to $0.07\,seconds$, between a sound reaching one ear versus the other.

Auditory scene analysis

The process of organizing the complex mixture of sounds reaching the ears into separate perceptual objects.

Auditory streaming

The process of grouping sounds by proximity in space, time, or frequency to separate them into distinct sources.

Continuity

An auditory phenomenon analogous to visual filling-in, where a sound is perceived as continuous even when interrupted by noise.

Shepard Tones

An auditory illusion involving mixtures of tones that create the appearance of a scale that ascends forever.

Sine-wave speech

Speech that has been stripped of acoustic cues but can still be recognized as speech if the listener has prior knowledge of the sentence.

e.g if i hear god save the queen from ambiguous but then it is actually played in its original form as the floor is slippery. then listening to ambiguous again i can hear the original.

Infrasound

Frequencies that fall below the typical human hearing range of $20\,Hz$.

Ultrasound

Frequencies that fall above the typical human hearing range of $20,000\,Hz$.

Tip link

The structures connecting the hairs on hair cells that assist in opening 'trap doors' for ion flow during bending.