FINAL EXAM Flashcards
What is Psychoacoustics?
The study of the relationship between the acoustic world and our auditor image of the world:
- How is sound perceived?
- How does perceived loudness relate to sound pressure?
What is sensation?
The awareness of an external stimulus or some change in the body caused by an external stimulus
Example: Loudness, pitch, sound source moving from left to right
What is perception?
Recognizing and interpreting a stimulus based on previous experiences
Example: Speech recognition, voice identification, recognizing a tune
What is the connection between physical stimuli and perception?
Intensity increases= Loudness increases
Frequency increases=pitch increases
Spectral complexity chnages=tibre changes
What is a threshold?
Perceptual: The point where the intensity level of a stimulus Is just large enough to cause a change in the mental response of a person affected by the stimulus
Hearing: lowest sound intensity level at which a listener can barely detect the presence of a sound
What are the 3 types of perceptual thresholds?
1) Absolute Threshold: minimum value
2) Terminal Threshold: Max Value( Uncomfortable loudness)
3) Difference Threshold: Smallest Difference ( You can detect the diff. in pitch, sound, etc)
What are the absolute threshold classifications?
1) Detection Threshold: Sensory
2) Recognition Threshold: Cognitive
What is the threshold of feeling?
Painful sounds to the eardrum
What is the auditory response area?
All the sounds we can hear
What is the threshold of hearing?
-Dependent on lower frequency/duration of a sound
-Lowest sound intensity at which a listener can barley detect the presence of a sound
What is the threshold at 500hz?
look at slide 10 on Nov.8 SS for graph
-200HL
What does this mean?—> it is the softest hearing level they can hear
What is the difference threshold?
-The smallest physical difference between two stimuli in which the listener can determine that two stimuli are perpetually different
-EX: Smallest perceivable change in the pitch of a sound
What is the difference threshold also known as?
- Difference Limen ( DL)
- Just noticeable difference( JND)
What are the detection threshold techniques
- YN(yes-no) technique: Listener responding to yes or no
- N-Alternative Forced Choice(nAFC) Technique : Signal presented–>listener indicates which interval contains the signal
Psychometric Function
- Region Below Threshold: No response
- Threshold region: Responding to it sometimes
- Region above threshold: Intensity is greater, easier to respond
What is signal detection theory?
- (SDT) a method of examining human decisions making in perceptual studies
- Looks at probability( likelihood)
- Considers trials at which are and are not presented
What are the four categories of response:
-HIt: If the signal is presented and the listener responds
- Miss: Signal presented, the listener does not respond
- False Alarm: Signal is not presented, Listener responds
- Correct Rejection: Signal not presented, Listener does not respond
Response criteria/Response bias
Every person develops an internal criterion that dictates how they will respond to a task under conditions of uncertainty
Where do the Yes/No and nAFC techniques originate from?
- Method limits
- Method of Constant (random) Stimuli
- Method of Adjustments
Method of Limits:
- Presenting listeners with the hearing level until they can’t hear it anymore
Benefits: Efficient/Don’t need to know where the threshold is at the start
Limitations: Threshold may be obtained w/o evidence that the listener was really listening
Method of Stimuli:
- Present stimuli to listeners and record the times they report hearing each one
Benefits: Provides a complete picture of sensitivity/Easy to administer
Limitations: Lots of trials, takes time
Method of Adjustments:
- Gives listener control/listener adjusts level until they can just not hear the stimulus
Benefits: Easy to administer/intuitive
Limitations: Potentially unreliable
Difference threshold?
- Intensity
-Frequency
-Duration
In general for people w/ normal hearing, the JND between two frequencies is:
_ Less than 1B
What is loudness?
The property of sound that allows sounds to be ordered on a scale extending from quiet (soft) to loud
Primary dependent on sound intensity
Other factors that impact loudness–> frequency, environment/room you are in, hearing loss, duration of sound
True/False: Our perception of loudness increases as a signal duration increases but only to a certain limit
True
How is stimulus intensity represented in the cochlea?
- In a healthy cochlea, a vibration of a basilar membrane increases with increasing intensity
- In a damaged cochlea, the thresholds are elevated
How is stimulus intensity represented in the auditory nerve?
- different AN Fiber types code for different stimulus intensity levels( high, medium, Low)
- Fibers increase fiberies
- AN Fibers increase firing rate as a stimulus (intensity) level increases
Measuring Loudness:
- Rating the relative loudness of sounds
How loudness changes with intensity - Matching the level of sound to be equally loud as another sound
How loudness changes with frequency
Rating technique for estimating loudness?
- Listener hears a sound
- Assigns number to sound according to perceived loudness
- Resilut= Loudness growth function ( Stimulus level and loudness level)
What is a one sone?
The unit of loudness
Loudness of 40dB at 1,000Hz
Loudness and Intensity: What is considered 2 sones?
Growth of loudness for 1,000Hz pure tones:
- A sound twice as loud would be assigned a value of 2
Loudness and Intensity: What is considered a half-sone?
A sound half as loud would be assigned a value of 0.5
Increasing the level of a sound from 50 to 60 dB SPL?
Loudness goes from two to four sones
For values above 40dB, what happens when you increase the sound by 10dB?
It doubles the loudness
Increase dB level of a sound from 40 to 50 dB SPL, loudness goes from one sone to two stones
Perceive loudness as doubling
What is loudness balancing?
The level of 1000Hz tone in dB SPL is the loudness level of the test sound:
- Measured in phones
- If the reference sound is 40 dB SPL 1000 Hz ton, it would have a loudness level of 40 phones
- If the reference were 70 dB SPL 1000Hz tone, the test sound would have a loudness level of 70 phons
What is Equal Loudness Curve?
Look at Slide 33 from Nov.15th
What are phons?
Unit of measure for loudness level
If phon increases to 10 what happens to sone?
It doubles in loudness
Effects of sensorineural hearing loss on loudness
- Losing volume and clarity
- age-related hearing loss at the cochlea b/c you have hair cell damage
-Rapid growth of loudness, due to outer hair cell loss - Loudness discomfort level is similar for listeners with normal hearing and SNHL
What is the threshold/uncomfortable level of normal hearing?
Threshold 0 dB Hl
Uncomfortable: 100 dB HL
What is the threshold/uncomfortable level of Sensorineural hearing loss?
Threshold 40dB HL
Uncomfortable 100 dB HL
What is the definition of 40 phons?
Perceived loudness of 40dB SL in 1000 Hz
Describe equal loudness contours:
- Measure of loudness level, equal in loudness but not the same as intensity
What is pitch?
Perceptual property of sound that allows them to be ordered from low to high
Perception depends on Frequency, duration, intensity, and spectral complexity
Do all sounds have pitch?
No, not all sound shave pitch even though all sound shave frequency content
Ears cant pick up on some sounds
What is a phantom harmonic?
When our brain fills in the gap/hears it
What is perfect pitch?
A persons ability to identify a musical note correctly upon hearing it or produced a given note on cue by singing
Where can we perceive the most suitable differences (JND) for frequency?
- Mid to high frequency
Why mid to high frequency?
Closer to resonance which we are more sensitive to those frequencies
How do we measure pitch perception?
Masking Experiments
Place Theory- Single Tone?
- Tones of different frequencies stimulate different basilar membrane locations
—> different pitches are perceived
What pitch do we perceive in place theory- single tone?
Complex tones
Where is the most displacement found in place theory- complex tone?
Fundamental frequency: associated with maximal stimulation of the baslier membrane
Pitch of Pure Tones?
- Only measure the pitch of a pure tone relative to another tone
- Present a reference tone to listeners, and ask them to adjust the frequency of a test tone so that it is 1/2 of that reference
- Mel= Unit of pitch
- 1000 mels= pitch associated with a 1000 Hz tone
What is the Frequency Discrimination Experiment?
- Involves 2 Alternate Force Choice experiments
- The listener hears two sounds with different frequencies and is asked to identify the higher/different frequency
What is pitch of complex sounds?
The Pitch of a complex sound is perceived as a pure tone at the fundamental frequency
What is Phantom Fundamental?
- Residue(phantom) pitch at the fundamental is perceived even when low-frequency harmonics are removed
Why is the phantom pitch perceived even when low-frequency harmonics are removed?
- The code for pitch of the sound is synchronized across multiple auditory filters (period/timing being synchronized)
- likely due to the synced-up timing of neural impulses in the auditory nerve
What is masking?
- The process by which the threshold of audibility for one sound is raised by the presence of another (masking) sound.
- Imagine trying to hear someone’s voice in a noisy restaurant*
What is taken into consideration in a masking experiment?
Masker: Noise–> WHat we use to cancel out the tone
probe: Tone–> Signal: persons voice we want to detect
What factors impact whether or not a signal can be heard?
The difference in intensity, frequency, and direction of incoming sounds
What are two types of masking?
- Informational: meaningful masking
- energetic: Noise–> tone/any kind of noise( air pressure moving is found here)
What is simultaneous masking?
When a sound is blocked by another sound that happens at the same time
What is on-frequency masking?
Masker is the same as the signal you are trying to hear
What is off-frequency masking?
- Different frequency than the masker
- Signal: You might have to raise the intensity
- More different to hear here because there are 2 different frequencies
What is the Upward Spread of Masking?
* look at slide 16 from Nov.29 to view the chart*
- Threshold goes up
- Spread of masking grows
- Grows more towards one side than the other
- Upward spread of making: increase Volume
What are Critical bands?
- Responsible for perceiving frequencies
- Cochlea can be considered to be a series of overlapping filters called critical bands
Each responds to a narrow range of frequency
This breaks an auditory signal into different frequency pieces
What happens when a pure tone is masked?
- When a pure tone is masked by a band of noise, as the bandwidth of the noise is increased, the masked threshold will increase
What happens when one sound is hidden by another sound but they are not presented at the same time?
Temporal masking: Not happening at the same time/ auditory masking due to non-simultaneous sounds
What are the two kinds of temporal masking?
- Forward masking
- Backward Masking
What is forward masking?
-The masker is presented slightly before the signal
-Masking of a tone by a sound that ends a short time before the tone begins
What is backward masking?
The masker is presented slightly after the signal
Masking of a tone by a sound that begins sometime later
How do audiologists use auditory masking?
Masking can be used with air conduction, bone conduction, and speech audiometry
Masking: What is Interaural attenuation?
- The decrease in intensity of a sound in one ear of a sound presented to the other ear as the sound is transmitted through the head
Why is it important to learn about auditory masking?
- Shows the presence of auditory filters( critical bands)
- Can help the response to tinnitus( Emotional response to tinnitus)
- Contralateral masking is helpful in audiology( diff. between ears)
- Background noise can mask students ability to hear
What is Binaural hearing?
-The improvement in hearing sensitivity when a person is listening with two ears compared to listening with one ear
- Threshold drops 2 or 3 dB ( more sensitive)
Why is Binaural hearing important for speech intelligibility?
- Because when the talker and unwanted noise occur together in space
What are Binaural Cues?
-Work together to give you a binaural advantage due to these cues
- Internal Intensity difference(IID)
- Interneural Time Differnce( ITD)
What is Internaural Intensity difference (IID)?
Sound intensity/Volume difference from one ear to another
What is Interaural Time Difference (ITD)?
* Look at slide 7 from Dec.1 to view the diagram*
Most sensitive to high frequency
“head produces shadow effect”
“ Move around so you can hear the difference”
What are monaural cues?
Monaural Cues are the directional cues resulting from sound reflections and diffractions around the ridges of the pinnae and upper torso
How does head motion play a key role?
Moving the head during continuous sounds can assist in locating a sound
How does familiarity play a key role?
A person who is familiar with a specific sound can more easily determine the direction and distance of a sound
What is lateralization?
-Identifying the location of a sound within the head is called lateralization
- When listening via headphones, there is an illusion that the sound Is located in various locations within the head
What is the cocktail party effect?
“selective hearing”
- Ability to focus on a single talker or conversation in a noisy environment
What impacts Binaural sensitivity?
- Hearing Loss
- Aging
- Traumatic brain Injury: Less binaural sensitivity/ Space for masking
4.Multiple Sclerosis - Brain Tumors
From the article, what level of noise was the threshold for noise exposure (AKA dose level) ?
- 85dBA for 8 hours
From the article, what was their average daily exposure?
- 89 dBA musicians and 79 dBA for non musicians
From the article, What were the main results of this study?
Musicians have more noise exposure–> outside music activities seem to be louder( leisure events)
How loud is too loud?
View the chart on slides 7-9 from Dec 6
- Normal Conversation: 60-70 dBA
- Lawnmowers: 80 to 100 dBA
- Sport events: 94 to 110dBA
- Sirens from emergency vehicles: 11-129 dBA
Fireworks: 140-160 dBA
What is the OSHA PEL Noise Dose?
View slideshow 10 from December 6th*
What factors impact Noise Exposure?
- Level
- Duration
- Distance
What are the two thresholds for Noise and Hearing Loss?
- Temporary Threshold shifts( TTS) –> Whne you hear a loud sound over and over again; hearing goes back to normal after having some hearing loss
- Permanent Threshold Shift ( PTS) –> Hearing does not go back to normal
What is Tinnitus?
The most common thing people experience
- Possible that some mechanical energy may be reflected back and forth along the cochlea, stimulating the hair cells, leading to self-sustaining oscillation
What is loudness recruitment?
-Rapid growth of loudness as. the level of a tone is increased
-More sensitive to loud sound
-Abnormal Sensitivity to loudness
What happens to OHC and IHC in the psychophysical tuning curves?
- OHCs damaged=IHCs intact
- OHCs intact= IHCs damaged
- OHCs damaged and ICHs damaged
What is the relation between people who have hearing loss and the concept of PTCs?
Individuals with cochlea hearing loss have more broadly tuned PTCs even at characteristic frequency
