Auditory Brain
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Questions and Answers

What primarily characterizes presbycusis?

  • Hearing loss due to cochlear implant interference
  • Hearing loss caused by excess oxygen in the cochlea
  • Temporary hearing loss due to loud noises
  • Age-related hearing loss affecting high frequencies first (correct)

Which of the following best describes noise-induced impairments?

  • Can be temporary and reversible or permanent (correct)
  • Always permanent and irreversible
  • Only affects low-frequency hearing
  • Caused only by loud explosions

What is the main consequence of excitotoxicity in hair cells?

  • Normal function of auditory neurons
  • Improved blood flow to the cochlea
  • Swelling and damage to auditory neurons (correct)
  • Increased production of oxygen-based free radicals

Which component of a cochlear implant is responsible for external sound capture?

<p>Microphone (B)</p> Signup and view all the answers

How does echolocation primarily help in sound localization?

<p>By emitting and processing sound echoes (D)</p> Signup and view all the answers

The precedence effect in sound localization helps in which of the following?

<p>Minimizing the effects of echoes in localization (C)</p> Signup and view all the answers

What visual cue factors influence sound localization according to the ventriloquism effect?

<p>Contiguity, plausibility, and contingency (B)</p> Signup and view all the answers

What term describes all sounds entering the ears at a given time?

<p>Auditory scene (D)</p> Signup and view all the answers

What is the first structure that auditory signals encounter on their pathway from the ear to the brain?

<p>Cochlear nucleus (D)</p> Signup and view all the answers

What is the primary function of the acoustic reflex in the auditory system?

<p>Limiting movements of the ossicles to prevent cochlear overstimulation (C)</p> Signup and view all the answers

Where are neurons coding for high frequencies located in the primary auditory cortex (A1)?

<p>Posterior/caudal end of A1 (A)</p> Signup and view all the answers

Which type of hearing impairment is caused by problems in the cochlea or auditory nerve?

<p>Sensorineural hearing impairment (B)</p> Signup and view all the answers

What is the primary purpose of pure tone audiometry?

<p>To estimate absolute thresholds for specific frequencies (D)</p> Signup and view all the answers

Which auditory pathway is responsible for identifying sound location?

<p>Core &gt; posterior auditory cortex &gt; posterior parietal cortex (A)</p> Signup and view all the answers

What is the role of the inferior colliculus in the auditory pathway?

<p>Integrating and unifying location cues for sound (C)</p> Signup and view all the answers

What distinguishes broadly-tuned neurons in the primary auditory cortex?

<p>They integrate components of complex sounds. (D)</p> Signup and view all the answers

What could cause conductive hearing impairment?

<p>Blockage of the ear canal (C)</p> Signup and view all the answers

How do sound waves change as they move towards an observer according to the Doppler effect?

<p>They increase in frequency. (D)</p> Signup and view all the answers

Which structure is responsible for receiving signals from inner hair cells in the ear?

<p>Cochlear nucleus (B)</p> Signup and view all the answers

What type of cues are primarily used to determine the azimuth of sound?

<p>Binaural cues (A)</p> Signup and view all the answers

How does interaural time difference (ITD) primarily contribute to sound localization?

<p>It gives the difference in arrival time of the same sound at each ear. (B)</p> Signup and view all the answers

Which factor is most critical for resolving distance of a sound?

<p>Intensity of the sound (B)</p> Signup and view all the answers

In which area of the brain is the interaural level difference processed?

<p>Lateral superior olive (C)</p> Signup and view all the answers

What occurs at 90 degrees concerning interaural time difference?

<p>ITD is at its peak. (D)</p> Signup and view all the answers

What is the cone of confusion in sound localization?

<p>Surface where two sound sources are indistinguishable (D)</p> Signup and view all the answers

Which type of cue helps resolve front/back ambiguity in sound localization?

<p>Monaural cues (B)</p> Signup and view all the answers

Which cue is primarily associated with determining the azimuth (horizontal) of sound?

<p>Binaural cues (D)</p> Signup and view all the answers

Interaural time difference (ITD) is more precise for higher frequency sounds.

<p>False (B)</p> Signup and view all the answers

What physical feature affects sound reflection and can create direction-specific frequency distortions?

<p>pinna</p> Signup and view all the answers

The analysis of sound spatial positions is often represented using __________ coordinates.

<p>spherical</p> Signup and view all the answers

Match the cue with its primary function:

<p>Interaural Level Difference (ILD) = Best for higher frequency sounds Interaural Time Difference (ITD) = Best for lower frequency sounds Spectral Cues = Resolve front/back ambiguities Intensity = Estimate distance of sound</p> Signup and view all the answers

What is the purpose of head motion in sound localization?

<p>To resolve ambiguities in ILD and ITD (A)</p> Signup and view all the answers

The zone called the cone of confusion helps differentiate between two sound sources at similar distances.

<p>False (B)</p> Signup and view all the answers

According to the inverse square law, if a sound source is twice as far away, how much lower is the intensity?

<p>4 times lower</p> Signup and view all the answers

What is auditory stream segregation primarily concerned with?

<p>Grouping sounds from a single source together (C)</p> Signup and view all the answers

Frequencies that are harmonics of different fundamental frequencies are typically grouped together.

<p>False (B)</p> Signup and view all the answers

What is the term for the process of extracting and organizing frequencies from multiple sound sources?

<p>auditory scene analysis</p> Signup and view all the answers

The process where sounds that are similar in pitch are perceived as part of the same auditory stream is known as ______.

<p>frequency similarity</p> Signup and view all the answers

Match the following processes with their definitions:

<p>Harmonic Coherence = Grouping frequencies that are harmonics of the same fundamental frequency Synchrony = Grouping sounds that begin or end at the same time Temporal Proximity = Grouping sounds based on their closeness in time Frequency Similarity = Grouping sounds based on similar pitches</p> Signup and view all the answers

What is the initial impact of presbycusis on hearing?

<p>Loss of high-frequency hearing (B)</p> Signup and view all the answers

Cochlear implants provide perfect reproduction of pitch.

<p>False (B)</p> Signup and view all the answers

What is excitotoxicity?

<p>Excess glutamate causing swelling and damage to auditory neurons.</p> Signup and view all the answers

The main external component of a cochlear implant that captures sound is the ______.

<p>microphone</p> Signup and view all the answers

Which of the following factors is NOT necessary for the ventriloquism effect to occur?

<p>Frequency of sounds (C)</p> Signup and view all the answers

Match the type of impairment with its description:

<p>Presbycusis = Age-related hearing loss affecting high frequencies Noise-induced impairment = Hearing loss due to exposure to loud sounds Excitotoxicity = Damage to neurons from excess glutamate Cochlear implant = Device that stimulates auditory neurons</p> Signup and view all the answers

Oxygen-based free radicals can contribute to hearing damage.

<p>True (A)</p> Signup and view all the answers

What does auditory scene analysis refer to?

<p>All the sound entering the ears during the current interval of time.</p> Signup and view all the answers

What is the auditory structure that receives signals from the inner hair cells in the ipsilateral ear?

<p>Cochlear nucleus (D)</p> Signup and view all the answers

The Doppler effect indicates a higher pitch when a sound source is moving away from an observer.

<p>False (B)</p> Signup and view all the answers

What is the primary role of the acoustic reflex in the auditory system?

<p>To protect the ear from damage by limiting ossicle movement.</p> Signup and view all the answers

The hearing impairment caused by damage to the cochlea or auditory nerve is known as __________.

<p>sensorineural</p> Signup and view all the answers

Match the following auditory structures to their primary functions:

<p>Cochlear nucleus = Processes signals from inner hair cells Inferior colliculus = Integrates auditory information from both ears Medial geniculate nucleus = Relays auditory signals to the cortex Superior olivary complex = Helps in sound localization</p> Signup and view all the answers

What is the primary auditory cortex (A1) responsible for?

<p>Sound frequency processing (D)</p> Signup and view all the answers

Tinnitus is characterized by the perception of sound caused by an external stimulus.

<p>False (B)</p> Signup and view all the answers

Name one common cause of conductive hearing impairment.

<p>Blockage of the ear canal or damage to the tympanic membrane.</p> Signup and view all the answers

The pathway responsible for determining the location of sound in the brain includes the core, posterior auditory cortex, and __________.

<p>posterior parietal cortex</p> Signup and view all the answers

Which auditory cue is primarily used to assist in determining sound frequency?

<p>Spectral cues (A)</p> Signup and view all the answers

Flashcards

Presbycusis

Age-related hearing loss, often starting with high-frequency sounds.

Noise-Induced Hearing Loss

Hearing loss caused by loud noises, potentially temporary or permanent.

Cochlear Implant

A device that stimulates auditory nerve fibers in the inner ear.

Echolocation

Using sound echoes to determine the location of objects.

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Precedence Effect

Sounds location perceived from the first arriving source.

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Ventriloquism Effect

Sound location based on visual cues.

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Auditory Scene Analysis

Processes multiple sounds entering the ears into understandable patterns.

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Excitotoxicity

Excess glutamate damaging auditory neurons.

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Sound Localization

The ability to perceive the location of a sound source in space.

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Azimuth

The angle in the horizontal plane that describes a sound source's location relative to the observer.

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Elevation

The angle in the vertical plane that describes a sound source's location relative to the observer.

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Minimum Audible Angle

The smallest angular separation between two sound sources of the same frequency that can be reliably distinguished.

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Interaural Time Difference (ITD)

The difference in arrival time of the same sound at the two ears.

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Interaural Level Difference (ILD)

The difference in sound level at the two ears for the same sound.

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Cone of Confusion

A hypothetical cone-shaped surface in auditory space where sounds from different locations have the same ILD and ITD.

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Spectral Cues

Frequency distortions caused by sound reflections off the pinna, providing information about the elevation of a sound.

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Doppler Effect

The change in frequency of a sound wave depending on the relative motion between the source and the observer. If the source is moving towards you, the frequency increases (higher pitch). If the source is moving away from you, the frequency decreases (lower pitch).

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Ascending Auditory Pathway

The pathway that carries auditory information from the ear to the brain.

It starts at the cochlea, then travels through the cochlear nucleus, superior olivary complex, inferior colliculus, medial geniculate body, and finally to the primary auditory cortex (A1).

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Cochlear Nucleus

The first stop in the brainstem that receives auditory signals from the inner hair cells of the cochlea.

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Superior Olivary Complex (SOC)

A brain stem structure that receives input from both cochlear nuclei. It plays a role in sound localization.

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Inferior Colliculus

A midbrain structure that acts like a 'switchboard' for auditory information. It receives information from the SOC and sends it on to the thalamus.

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Medial Geniculate Body (MGB)

The last stop in the thalamus before information reaches the auditory cortex.

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Primary Auditory Cortex (A1)

The part of the brain responsible for the conscious perception of sound. It receives auditory information from the MGB and processes it further.

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Tonotopic Organization

The way that auditory information is organized in the brain. Neurons that respond to low frequencies are located in one region, while neurons that respond to high frequencies are located in another region It begins on the basilar membrane and is maintained through the ascending auditory pathway into A1.

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Acoustic Reflex

A protective mechanism that contracts the tiny muscles attached the ossicles (middle ear bones) to reduce the amount of sound reaching the cochlea.

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Sound Localization: Time & Intensity Cues

The brain uses the differences in the time of arrival and the intensity of sound between the two ears to figure out where a sound is coming from. This processing occurs in the Superior Olive (SOC) and Cochlea (cochlear amplifier).

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What is Sound Localization?

The ability to pinpoint the location of a sound source in space.

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What are Binaural Cues?

Clues used for sound localization that involve both ears.

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What are Monaural Cues?

Clues used for sound localization that involve just one ear.

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What is the Cone of Confusion?

A region in space where sound sources create the same ILD and ITD, making their location ambiguous.

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What are Spectral Cues?

Frequency distortions caused by sound reflections off the pinna, providing information about the elevation of a sound.

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How does head motion help in sound localization?

Moving your head changes the ILD and ITD, resolving ambiguity from the Cone of Confusion.

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Auditory Stream Segregation

Perceptually grouping sounds that belong together (like notes from the same instrument) and separating them from other sounds

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Harmonic Coherence

Frequencies that are multiples of a fundamental frequency tend to be grouped together, contributing to our perception of individual sound sources.

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Synchrony

Sounds that start, stop, or change at the same time are more likely to be perceived as belonging to the same source.

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Frequency Similarity

Sounds with similar pitches tend to be grouped together, contributing to our perception of a single auditory stream.

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Direct vs. Reflected Sound

Direct sound reaches the listener directly from the source, while reflected (echo) sound bounces off surfaces before reaching the listener.

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Where is sound processed?

Sound is processed in the brainstem, specifically in the Superior Olive for localization, the Cochlear Nucleus for spectral cues, and the Inferior Colliculus for unifying location cues.

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What is A1?

Primary Auditory Cortex (A1) is the area in the brain where you consciously hear sound. It's located in the superior temporal gyrus.

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What is Tonotopic organization?

The arrangement of neurons in the auditory system, where cells responding to low frequencies are near those responding to high frequencies, and this pattern follows the basilar membrane to A1.

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What is the acoustic reflex?

A protective mechanism in the ear: tiny muscles contract to reduce the sound reaching the cochlea, preventing damage from loud noises.

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Sound Localization: Time vs. Intensity

The brain uses the difference in sound arrival time (ITD) and loudness (ILD) between the two ears to determine the location of a sound.

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What and Where Pathways

The 'what' pathway analyzes sound identity, while the 'where' pathway determines sound location. These pathways originate in A1 and project to different areas of the brain.

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What is Conductive Hearing Loss?

A hearing impairment caused by problems with sound transmission to the cochlea, like earwax or damage to the eardrum.

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Study Notes

Sound Localization

  • Cochlear nucleus receives signals via Type 1 auditory nerve fibers from inner hair cells in the ipsilateral ear.
  • Spatial hearing uses spherical coordinates to represent a source's position.
  • Azimuth: horizontal angle.
  • Minimum audible angle: minimum angular separation for 75% correct judgments of same-frequency tones.
  • Elevation: vertical angle.
  • Distance.
  • Hearing is more accurate in the horizontal plane than the vertical.

Brainstem Processing

  • Interaural level difference (ILD): difference in sound level at the two ears.
  • Processed in the lateral superior olive to the inferior colliculus.
  • Acoustic shadow: reduction in sound level on the opposite side of the head due to sound waves being blocked.
  • Interaural time difference (ITD): difference in arrival time at the two ears.
  • Processed in the medial superior olive to the inferior colliculus.
  • ITD peaks at 90 degrees.

Types of Cues

  • Binaural cues: provide azimuth (horizontal position) information.
  • ILD for higher frequencies.
  • ITD for lower frequencies.
  • Neural code for lower frequencies is phase-locked.
  • Lower frequency precision is less precise than higher frequencies..
  • Cone of confusion: hypothetical cone-shaped surface where sound source locations are difficult to distinguish due to similar ILD and ITD values.
  • Head movement resolves ambiguity

Monaural Cues

  • Provide elevation (vertical position) information.
  • Sound reflections off the pinna create direction-specific frequency distortions.
  • Spectral cues resolve front/back ambiguities for sound location.
  • Distance perception cues:
  • Intensity (inverse square law); double the distance, the intensity is quartered.
  • Relative intensity of direct vs. reflected sound.

Doppler Effect

  • Frequency of a sound wave changes if the sound source is moving relative to the observer.
  • Towards = higher frequency, pitch.
  • Away = lower frequency, pitch.

Auditory Pathway

  • Sound > cochlea > cochlear nucleus (brain stem)
  • Superior olivary complexes > inferior colliculus
  • Medial geniculate nucleus (thalamus)
  • Primary auditory cortex (A1).

Descending Pathways

  • Numerous pathways connect auditory cortex, subcortical areas, and the ears.
  • Acoustic reflex: helps protect the ear from damage.

Processing in the Brainstem

  • Localization based on time and intensity.
  • Spectral cues.
  • Integration of location information.

Primary Auditory Cortex (A1)

  • Located in superior temporal gyrus (STG).
  • Core region (A1) + belt + parabelt regions.
  • Tonotopic organization (lower frequencies in anterior/rostral A1; higher frequencies in posterior/caudal A1).

Hearing Disorders

  • Hearing impairment = decreased ability to detect or discriminate sounds.
  • Tinnitus: persistent perception of sound without an external stimulus.
  • Conductive hearing loss: problem with sound transmission to cochlea (e.g., earwax, damage to eardrum).
  • Sensorineural hearing loss: damage to cochlea, auditory nerve, or auditory areas (e.g., age, noise exposure).
  • Age-related hearing loss (presbycusis): affects high frequencies first.
  • Noise-induced hearing loss: loud noise can cause temporary or permanent damage.
  • Hair cell death: excitotoxicity; reduced blood flow can damage auditory neurons.

Cochlear Implants

  • Linear array of electrodes implanted in the cochlea to stimulate auditory neurons.
  • Effective in restoring hearing, but pitch reproduction is not perfect.
  • Beneficial for children born deaf.

Auditory Scene Analysis

  • Contextualization of sound signals.
  • Auditory scene: sounds present at one time.
  • Extraction of sound sources and distinct streams of sounds.
  • Auditory stream segregation.

Simultaneuous and Sequential Grouping

  • Harmonic coherence.
  • Synchronous sounds.
  • Frequency similarity.
  • Temporal proximity.

Seeing by Hearing

  • Sensory Substitution Devices.

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Auditory Brain PDF

Description

This quiz covers the principles of sound localization, including how signals are processed in the cochlear nucleus and brainstem. It explores key concepts such as interaural level difference and interaural time difference, along with the types of cues used for spatial hearing. Test your understanding of how our auditory system perceives sound direction and distance.

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