Auditory Sensitivity Flashcards
Absolute sensitivity:
- measure of central tendency
- how much sound intensity is required for the average person to just barely detect it.
Threshold
Thresholds of audibility are plotted as the threshold in dB SPL as a function of frequency
What is a low threshold?
What is a high threshold?
Low threshold = high sensitivity
High threshold = low sensitivity
The shape of the audibility curve:
Plots the frequency response of the middle ear
Low frequency sounds aren’t transmitted well due to stiffness
High frequency sounds aren’t transmitted well due to weight of ossicles etc.
Middle frequencies transmitted best due to least reflectance of sound
The resonant frequency of the middle ear is _______Hz
1800
Threshold of audibility:
Minimum audible field (MAF) threshold:
SPLs for pure tones @ absolute threshold measures in a free field (both ears, Facing the source, 1 m away from source)
Threshold of audibility
Minimum auditory pressure (MAP) threshold:
Decibel threshold of SPL @ or near the listener’s tympanic membrane
Need to use headphone:
Supra aural = fit over ear
Circum aural = fit around pinna
Insert earphone
Upper limits of hearing:
Pain sensation occurs at ____ dB SPL
Depends on what?
120
Depends on how sensation is defined for patient
Loudness does NOT mean intensity
Standardization refers to what?
What most people hear
Depends on where you live
1954 British standard
1951 American standard
–> differed by 10dB
ISO (international organization for standardization)
Duration:
For a given frequency, threshold for power _______ as duration _________ :
Decreases
Increases
- the longer the signal, the easier to detect
- shorter the signal, the more power needed to detect it
Temporal integration (intensity-time-trade-off):
Auditory system requires about 300ms for perfect performance
If signal is less than 300ms, then power level must be increased
Once you decrease time you must increase power for same level of performance
