hearing review questions

3. Can you match the physical dimensions (amplitude, frequency, complexity) of sound to their perceptual dimensions – which parts of your subjective experience of sound does each dimension correspond to?

  • Amplitude corresponds to perceived loudness

  • frequency corresponds to perceived pitch 

  • Complexity corresponds to timbre or quality of sounds

4. What scale is used to measure sound intensity and at what sound intensity do we experience pain?

  • Decibels 

  • Pain sounds are experienced around  120- 130 dB

5. What is the range of frequencies for human hearing?

  • 20 Hz - 20,000 Hz

6. What is so remarkable about infrasound? How does it impact the human nervous system and why might this type of response be an evolutionary advantage?

  • Infrasound is sound below 20 Hz. It impacts the human nervous system because it can trigger and activate the fight-or-flight response. This may have helped human early to detect dangers, and provide a survival advantage. 

7. Trace sound information through the auditory system starting with the pinna and ending at the dorsal and ventral streams? Your response should include the following structures in the correct order: tympanic membrane, medial geniculate nucleus, stirrup, primary auditory cortex, basilar membrane, inferior colliculus, medulla, oval window, anvil, hammer, auditory nerve, auditory canal

  • Pinna: Sound waves first enter the outer ear through the pinna, which helps to funnel and direct them into the ear.

  • Auditory Canal: The sound waves travel through the auditory canal, where they are directed toward the eardrum.

  •  (Eardrum): The sound waves cause the tympanic membrane to vibrate. These vibrations are essential for transmitting the sound energy to the middle ear.

  • Hammer (Malleus): The vibrations from the eardrum cause the hammer, or malleus, to vibrate. This is the first of the three small ossicles in the middle ear.

  • Anvil (Incus): The vibration is then transferred to the anvil, or incus, the second of the ossicles.

  • Stirrup (Stapes): Finally, the vibration moves to the stirrup, or stapes, which is the third ossicle. The stapes amplifies the vibrations and sends them to the inner ear.

  • Oval Window: The stapes vibrates against the oval window, which is a membrane that separates the middle ear from the cochlea in the inner ear. This movement transfers the vibrations into the fluid-filled cochlea.

  • Cochlea and Basilar Membrane: Inside the cochlea, vibrations create waves in the fluid, which cause the basilar membrane to move. Hair cells along the basilar membrane convert this mechanical movement into electrical signals.

  • Auditory Nerve: These electrical signals are picked up by the auditory nerve fibers, which transmit the signals from the cochlea to the brainstem.

  • Medulla: The auditory nerve carries the signals to the cochlear nucleus in the medulla. From here, the signals begin to ascend through various brainstem structures.

  • Inferior Colliculus: The signal continues to the inferior colliculus in the midbrain, which plays a role in processing spatial aspects of sound and coordinating responses.

  • Medial Geniculate Nucleus: The signal is then relayed to the medial geniculate nucleus (MGN) of the thalamus, which acts as a relay station and further processes the auditory information.

  • Primary Auditory Cortex: From the MGN, the auditory signals reach the primary auditory cortex in the temporal lobe, where basic features of sound, such as pitch and rhythm, are processed.

  • Dorsal and Ventral Streams: Finally, auditory information is distributed along two pathways:

  • Dorsal Stream: Processes spatial information (“where” sounds are coming from).

  • Ventral Stream: Processes the characteristics of the sound, including object identification (“what” the sound is)

8. What is the role of the hammer, anvil and stirrup in an audition?

  • In the audition these are the 3 tiny bones called the ossicles. The hammer starts the process by receiving vibrations from the eardrum 

  • The anvil is the bridge between the hammer and stirrup which acts as a connector. 

  • The stirrup amplifies vibrations before passing into the inner ear, where they are transformed into signals for the brain. 

9. What structures in the auditory system are responsible for the transduction of sound waves into action potentials?

  • Hair cells in the organ of corti are responsible for turning sound waves into action potentials. When sound enters the cochlea, it moves the hair cell, opening channels that let potassium ions in, which causes cells to send electrical signals. The cells travel along the auditory nerve to the brain 

10. If you could jump up and down on the two ends of the basilar membrane, what major difference would you observe in comparing the apex to the base?

  • You would observe a difference between the apex and base. The base of the basilar membrane is narrower and stiffer, leading to higher frequency sounds being processed there. Vibrations at the base would correspond to higher pitches, while those at the apex would correspond to lower pitches

11. Describe how the basilar membrane is designed to respond to sounds of different frequency.

  • The basilar membrane has a narrow base for high-frequency sounds and a wide apex for low-frequency sounds

12. What type of stimulus is required to activate the hair cells? Once they are activated, where do they send their signals?

  • Sound waves activate hair-cells, auditory nerve guides signals to the brain   

13. Describe the general layout of the primary auditory cortex and how it responds to sounds of different frequencies.

  • In the temporal lobe (mainly focusing on auditory information) 

    • Different frequencies of sound stimulate different areas 

      • In response to high frequencies its processed anterior of the brain

      • In response to low frequencies its processed posterior of the brain 

14. Identify the function(s) that would be impaired if the primary auditory cortex was damaged.

  • Functions that would be impaired if the primary auditory cortex were damaged.

    • You wouldn't be able to hear clearly 

      • Sound perception and recognizing and interpreting sound

    • Auditory localization = identifying where sounds are coming  from 

    • Language processing 

17. What specific impairment would result from damage to Wernicke’s area and how would it differ from damage to Broca’s area?

  • Impairment to wernicke's area would impair the ability to understand spoken and written language

  • Broca's area would impair the ability to form grammatically correct sentences followed by slow slurred speech. 

18. What is the primary purpose of a cochlear implant? Who are the best candidates for these devices and why?

  • The primary purpose of a cochlear implant is to help hear better, the best candidates for these devices are people with impaired hearing, such as older people, or even people born with bad hearing.