The document discusses how human hearing works. It describes sound as pressure variations in air or other mediums that can be detected by the ear. It explains that the ear has an intensity range of over 10 trillion units, detecting sounds from 20-20,000 Hz and distinguishing sounds that are only 1 Hz different. The ear consists of the outer, middle, and inner ear. The middle ear contains ossicles that transmit sound to the cochlea in the inner ear, where hair cells convert sound waves to nerve signals sent to the brain.
The document discusses how human hearing works. It describes sound as pressure variations in air or other mediums that can be detected by the ear. It explains that the ear has an intensity range of over 10 trillion units, detecting sounds from 20-20,000 Hz and distinguishing sounds that are only 1 Hz different. The ear consists of the outer, middle, and inner ear. The middle ear contains ossicles that transmit sound to the cochlea in the inner ear, where hair cells convert sound waves to nerve signals sent to the brain.
The document discusses how human hearing works. It describes sound as pressure variations in air or other mediums that can be detected by the ear. It explains that the ear has an intensity range of over 10 trillion units, detecting sounds from 20-20,000 Hz and distinguishing sounds that are only 1 Hz different. The ear consists of the outer, middle, and inner ear. The middle ear contains ossicles that transmit sound to the cochlea in the inner ear, where hair cells convert sound waves to nerve signals sent to the brain.
The document discusses how human hearing works. It describes sound as pressure variations in air or other mediums that can be detected by the ear. It explains that the ear has an intensity range of over 10 trillion units, detecting sounds from 20-20,000 Hz and distinguishing sounds that are only 1 Hz different. The ear consists of the outer, middle, and inner ear. The middle ear contains ossicles that transmit sound to the cochlea in the inner ear, where hair cells convert sound waves to nerve signals sent to the brain.
C LINIC AL AU DIO LO GY I PAC S 5601 AMANDA O RTMANN, PH D What is sound? Perceptual Properties Sound is just movement (pressure) of molecules in the air (medium):
Physical Properties What can we hear? Intensity: Frequency: Duration: What can we hear? Intensity: measured in decibels or dB SPL (sound pressure level) Frequency: Duration: Dynamic range of hearing = loudest sound that you can tolerate – the softest sound that you can hear
So what is the intensity range of human hearing?
What can we hear? Intensity: The softest sound that we can hear is one billionth of an atmospheric pressure Frequency: ◦ We can detect the motion variation the length of 1/10 of an atom Duration: Dynamic range of hearing is on the order of 10 trillion units
Let’s put that in perspective. . .
What can we hear? Intensity: Frequency: Duration: What can we hear? Intensity: Dynamic range of hearing is on the order of 10 trillion units Frequency: But wait . . . what about the audiogram? Duration: What can we hear? Intensity: Dynamic range of hearing is on the order of 10 trillion units Frequency: But wait . . . what about the audiogram? Duration: What can we hear? Intensity: Dynamic range of hearing is on the order of 10 trillion units Frequency: But wait . . . what about the audiogram? Duration: dB HL dB Hearing Level
(normalize)
dB SPL dB Sound Pressure Level What can we hear? Intensity: We can hear from 20 -20,000 Hz Frequency: Duration: Better yet, we are able to distinguish 1 Hz steps. What can we hear? Intensity: We can detect gaps in sounds that are on order of milliseconds Frequency: People with normal hearing can detect gaps as low as 5 ms with over 96% accuracy. 4 ms with 70% accuracy . . . 2 ms with 30% accuracy. Duration: So how do we hear? Hearing Overview The middle ear If we did not have a middle ear system, how much sound energy would be reflected or lost? ◦ More than 90% ◦ 80% ◦ 75% ◦ 50%
Eardrum Response
Ossicles
Entire Auditory Transduction Video is in Canvas
The inner ear The inner ear
Auditory Hair Cells
cochlea Nerve Fibers Hearing Overview Hearing Loss Outer and Middle Ear: ◦ Conductive Loss
Inner Ear ◦ Sensorineural Loss
Both ◦ Mixed Loss
These are the types of
hearing losses Your assignment . . . Make a video of yourself giving a 3-5 minute explanation of how we hear. I just want you to put everything in your own words; the explanation can be geared toward your peers. (soon we will tailor this so that it is for patients, families, etc.) The assignment link can be found in Canvas. Image Credits What is sound ◦ http://apg.mechanicsofhearing.org/
