Hearing Science Quiz 5

List one nucleus in the central auditory system

Cochlear nuclei-First stop in the brainstem. Characterized by complex response patterns that analyze the time and spectral information of the incoming signal. 

List one auditory tasks

Auditory Identification (Recognition): The ability to correctly recognize or label a sound stimulus (e.g., identifying a specific tone or speech sound).

Displacement in the basilar membrane is only caused by characteristic frequency (T/F)

FALSE -because Every location on the basilar membrane is sensitive to a range of frequencie

The method of limits with adaptive methods is the only way to detect a single threshold (T/F)

FALSE - bc method of constant stimuli and method of adjustment can detect single thresholds

Explain spontaneous firing rates

 Auditory neurons respond to sounds near their preferred frequency

Func- helps the ear stay sensitive to quiet sounds while preventing loud sounds at that frequency from overwhelming the system 

Explain psychometric functions

a mathematical model that describes the relationship between an auditory stimulus and a listener's ability to detect, discriminate, or identify that stimulus

What is the central auditory system made of?

Auditory Brainstem, auditory forebrain, forming the main auditory pathway.

What is the Auditory Brainstem composed of?

1. Cochlear Nuclei (CN)

2. Superior Olivary Complex (SOC)

3. Nucleus of the Lateral Lemniscus (NLL)

4. Inferior Colliculus (IC)

Divisions of the Cochlear Nuclei

 Anteroventral Cochlear Nucleus (AVCN), Posteroventral Cochlear Nucleus (PVCN), and Dorsal Cochlea (DCN)

Superior Olivary Complex (SOC)

Input: Receives bilateral inputs (from both ears). 

Function: Primary nucleus for sound localization

Divisions and Functions within the SOC

1. Medial Superior Olive (MSO): Processes interaural time differences (ITD) for low-frequency sound localization. 

2. Lateral Superior Olive (LSO): Processes interaural intensity differences (IID) for high-frequency sound localization. 

Nucleus of the Lateral Lemniscus (NLL)

Function: Further relay point; contributes to temporal processing. 

 Inferior Colliculus (IC)

 Input: Receives input from all lower nuclei. 

Function: Combines the analysis of complex sound features and sound direction in space simultaneously.

 What is the Auditory Forebrain Nuclei composed of?

Medial Geniculate Body (MGB), Auditory Cortex (AC)

 Medial Geniculate Body (MGB)

 Function: The thalamic relay station. Processes and relays specific, detailed auditory information to the auditory cortex.

Auditory Cortex (AC)

○ Divisions: Primary Auditory Cortex (AI) and Secondary Auditory Cortex (AII).

Function: Tonotopic organization: Frequency mapping is maintained. Detection of complex features: Neurons respond to specific patterns, such as frequency-modulation (FM) detectors and temporal-modulation detectors. 

Auditory Attention Neurons: Respond only to novel stimuli, quickly becoming habituated to repeated sounds. 

What is Psychoacoustics?

The study of the relationship between acoustic features (physical sound properties) and psychological features (auditory perception).

Types of Auditory Perceptual Task

1. Auditory Sensitivity (Detection)

2. Auditory Discrimination

3. Auditory Identification (Recognition)

What is Auditory Sensitivity (Detection)?

Determining the minimum physical level of a sound required for a person to detect its presence (e.g., finding the absolute threshold of hearing). 

What is  Auditory Discrimination?

Measuring the smallest change in a sound's physical property (like frequency or intensity) that a person can detect (e.g., just noticeable difference, or JND). 

What is  Auditory Identification (Recognition)?

The ability to correctly recognize or label a sound stimulus (e.g., identifying a specific tone or speech sound). 

Physiology of Inner ear

Turning curve(frequency response) and nonlinear compression at CF

auditory neuron

spontaneous activity, tuning curve (freq. response), intensity response (dynamic range), and phase locking.

Psychoacoustic Methods-Two classic methods  to measure auditory perception

1. Method of Limits- It uses both ascending (starting below threshold and increasing the stimulus level) and descending (starting above threshold and decreasing the stimulus level) series. ● Stimulus level changes by a fixed step size. 

○ Adaptive Method: A variation where the presentation level is based on the subject's previous response, often following an "up-down rule"

2. Method of Constant Stimuli-  This method presents a fixed, equal number of stimuli at each predetermined level. 

   The results are plotted as a psychometric function, showing the percentage of correct or "yes" responses for each stimulus level. The threshold is defined as the stimulus level corresponding to a certain percentage point on the psychometric function (e.g., the 50% or 75% correct point). - Scaling Method: aims to directly establish the correspondence between the physical properties of sounds and their subjective perception (e.g., relating intensity to loudness or frequency to pitch).