Section 2 Flashcards
What is the dynamic range of hearing?
The range of intensity of which the fiber will increase its intensity rate as the sound increases. Only about 50dB
Name the two efferent pathways into the cochlea
1.) Crossed Olivocochlear Bundles
2.) Uncrossed Olivocochlear Bundles
What do we mean when we characterize the classic phsycophysical methods described by Fechner as “inefficient?” Who modified one of these methods to be more efficient and what is his method called?
Bekesy Tracking: Von Bekesy thought that the classic methods were inefficient and wasted everyone’s time because you would spend a significant amount of time presenting too loud/soft sounds that was nowhere near a person’s threshold. He cleans up the Method of Limits and starts with a loud sound, goes down until they can’t hear it, then goes back up until they can, back down, etc and then takes the average of the reversal points
What are the 3 psychophysical methods described by Fechner?
1.) Method of Constant Stimuli
2.) Method of Limits
3.) Method of Adjustment
In SDT, what is a hit?
A signal is presented and you say “yes”
In SDT, what is a miss?
A signal is presented and you say “no”
In SDT, what is a false alarm?
A signal is not presented and you say “yes”
In SDT, what is a correct rejection?
A signal is not presented and you say “no”
How does hearing sensitivity as plotted on an audiogram show thresholds differently from when plotted on a threshold function? Why are audiograms plotted this way?
Audiograms use a 0dB HL scale because we are comparing the subject’s hearing with the average person’s hearing. A threshold function uses the dB SPL scale. We are also asking different questions. The threshold function asks “What is the smallest sound a person can hear?” and the audiogram is asking “What can I hear compared to everyone else?”
What is 0db SPL?
0dB SPL is a method of measuring hearing level using an onjective level of sound. It is about 20 micropascals
What is 0dB HL?
0dB HL is the average of a large set of human hearing to define a normal hearing range. It is used to compare to the average person’s hearing level. A score of 0dB HL at different frequencies would mean you have no hearing loss
What does the smallest sound a person can hear depend on?
1.) Question you’re asking
2.) How you measure it
3.) Frequencies
4.) Continuous vs intermittent sounds
5.) Duration of sound
How would you use the concepts of Signal Detection Theory to create a test to differentiate between 2 different diagnoses?
You should use SDT to create a test with a high hit rate and a low false alarm rate. A high hit rate means the test has good sensitivity, which means that it will actually detect a disorder when it is actually present. A low false alarm rate means the test has good specificity, which means if a disorder is not present then the test will not detect anything
What is a high-pass and low-pass filter?
High pass: only frequencies above a certain frequency can pass through
Low pass: only frequencies below a certain point can pass through
Why do we care about the cubic difference tone?
-It’s why beating occurs
-Product of OAE, which we use to assess the function of OHC and identify potential HL related to cochlear damage
What is the cubic difference tone?
Difference tone that generates the biggest response on the BM
2f(1)-f(2)
What is the goal of Critical Band Theory?
To find the narrowest band of noise possible that will still effectively mask a target
What is Critical Band Theory?
The range of frequencies that activates the same part of the BM. When multiple tones are close in frequency, they can share hair cells on the BM and fall within the same critical band
What does Critical Band Theory help to explain?
When the target sound and masker fall into the same critical band, they get “mixed” together and are perceived as one sound
What is afferent innervation density?
The distribution of afferent fibers is not equal across the entire BM. They are more dense/concentrated toward middle frequency ranges (1000-4000Hz). This is where we are more behaviorally sensitive and this is where the afferent fibers are more multivesicular
What is the Upward Spread of Masking?
The phenomenon in which a lower frequency masker masks a signal more effectively than a masker at the signal frequency
**If a lower frequency sound is too intense, they can mask over the high frequency regions of the BM
What is Signal Detection Theory?
A framework that allows you to separate a person’s hearing sensitivity from their response bias. There is always some sound present because of physiological activity. People also have biases and make internal decisions about their criterion and where to set it
What do we mean by sensitivity in SDT?
Sensitivity is how far apart the means of the distributions are
What are the 3 results of Wegel and Lane’s study with beats?
1.) When the target and masker are close in frequency, the masker is more effective
2.) When the target and masker are extremely close in frequency, beating occurs
3.) Beating occurs at harmonics of the masker frequency because of cochlear nonlinearities
What is masking?
-The ability of one sound to interfere with the perception of another
-Measured by how much the threshold of a signal increases with the introduction of another sound
Why is masking relevant?
-Everything you listen to has interference
-Used in clinical audiology to measure thresholds if someone has an asymmetric hearing loss
What is d-prime?
The measure of sensitivity
Why is the audiogram line different than the dB SPL line?
dB SPL is a direct measurement of sound pressure level, regardless of individual hearing ability
The audiogram line uses the dB HL scale, which is measuring a person’s hearing threshold relative to the average person’s hearing ability (normal hearing curve)
What are the 5 things a person can do with a sound?
1.) Detection
2.) Discrimination
3.) Localization
4.) Identification
5.) Comprehension
What is Weber’s Law?
The ratio of the smallest noticeable change in a stimulus to the original stimulus is a constant
Change in intensity/reference intensity = constant (k)
Why is the dB scale logarithmic?
It must be compressed to make a mathematically manageable scale
Why do we use different dB scales?
They reflect the question you’re asking.
Audiograms use dB HL.
dB SPL would be used to indicate potential for hearing damage
What does a spectrum measure?
How amplitude changes as frequency changes
What does a waveform measure?
Changes in intensity over time
What does a spectrogram measure?
Changes in frequency over time
What types of things can be maskers/masked?
Target signals: pure tones, speech
Maskers: pure tones, speech, steady state noise
What is beating? What is the perceived frequency and the fluctuation rate?
-Fluctuating tones when 2 tones extremely close in frequency are played on top of each other
-Perceived frequency is average between the 2 tones
-Fluctuation rate is the difference between the 2 tones
What is backward masking?
-Signal precedes the masker
-Masker is presented after the target
What is forward masking?
-Signal start after the masker stops
-Masker is presented before the target
Why does forward masking happen?
Auditory system is fatigued from processing masker
What are the 2 types of combination tones?
1.) Summation tones
2.) Difference tones
What are the 3 kinds of adverse conditions of sound?1
1.) Degradation of the sound source
2.) Degradation of the listening environment (background noise)
3.) Degradation at the level of the listener
What is the Method of Adjustment
Give a person a dial, present a sound and the person uses the dial to adjust the level until they can barely hear it. Repeat. Average all the points/levels of the softest sound they can hear
What problem does threshold bring up?
Why are responses not yes/no 100% of the time? You either hear it or you don’t….
What is physiological noise?
-Breathing, respiration, heartbeats, etc.
-Spontaneous auditory nerve firings
What does SDT argue that it can do?
SDT argues that it can separate sensitivity from bias
Why would children appear to perform poorly on a hearing test?
They may be nervous and more prone to give liberal/conservative responses because of this
What types of factors would influence people to give liberal/conservative responses on a hearing test?
-Children
-Older adults trying to prove or deny a hearing loss
-Outside influences, such as monetary gain
What is the error of anticipation?
You anticipate a shift, so you start thinking that you should change your response before you actually should
What is the error of habituation?
You get so used to making a response that you keep making the same response over and over when you shouldn’t
What are 2 problems that can occur with the Method of Limits?
1.) Error of Habituation
2.) Error of Anticipation
What is psychophysics?
The mapping of the physical characteristic of a stimulus to a psychological percept
What frequency range are we most sensitive to?
1000-4000Hz
0dB SPL = ___
20 micropascals
What are 4 types of masking?
1.) Tone-on-tone masking (beats, and upward spread of masking)
2.) Tone-in-noise
3.) Speech in Noise
4.) Temporal Masking
Does Weber’s Law hold for frequency changes?
Yes, it kind of works between 500Hz and 2000Hz. Outside of that range, it does not
Does Weber’s Law work for intensity?
“Near miss”. Ideally, it would be a straight line, but combining everything in the graph, it looks like a slightly down-turned line
Does Weber’s Law work for duration?
It looks like it for the function being used (change in I/I) instead of ((change in I/I)/I). But when you actually look at the num,bers on the x-axis, then it does not work because it uses a log scale
What are 3 ways to visualize sound?
1.) Spectrum
2.) Spectrogram
3.) Waveform
