# hearing exam6

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1. Classical Measurement Methods
• 1.Method of Limits
• 3.Method of Constant Stimuli
2. Method of Limits
• –Stimulus is presented
• –Subject indicates whether or not they heard it
• –Tester manipulates the level of the stimulus based on the subjects response
3. Run:
4. Number of individual presentations of a stimulus
5. –Ascending run:
stimulus level begins below threshold and is raised until the subject can barely hear the tone
• –The subject controls the stimulus level by turning an unmarked knob
• –Stimulus changes in a continuous fashion (rather than in fixed steps)
7. Method of Constant Stimuli
• Presents various stimulus levels in random order
• •Like the Method of Limits but not sequential
• –No ascending or descending runs
• -Results are tabulated and plotted as a “psychometric function”
8. –Psychometric Function:
• a plot which shows the percentage of times the stimulus was heard at each level
• –Threshold
9. Direct Scaling
10. subject establishes the relationship between a standard and comparison stimulus
• -
• Major Approaches to Direct Scaling:
• •Ratio Scales
• •Magnitude Scales
11. Ratio Estimation:
12. expresses subjective magnitude of one stimulus as a ratio of the other stimulus
–For example: compared to the standard tone, the comparison tone might be twice as loud
13. Ratio Production:
14. adjusts the magnitude of a stimulus to produce a specific ratio of the other
–For example: the subject adjusts the intensity of the stimulus until it is twice as loud as the standard tone
15. Magnitude Estimation:
• –A series of stimuli are presented that vary in some dimension such as intensity or frequency.
• –The subject assigns a number to each stimulus to represent its loudness or pitch.
16. Magnitude Production:
–Physical magnitude adjusted to correspond with numbers indicating perceived magnitude
17. Human Hearing Thresholds
• Humans have sensitivity over a broad range of frequencies: 10 Hz – 20,000 Hz
• •Hearing sensitivity is best between 2000 – 5000 Hz
• •Hearing sensitivity is poor below 100 Hz and above 10,000 Hz
18. 1.Minimum Audible Pressure (MAP):
• based on monaural (one ear) thresholds with earphones
• –Measure sound pressure in the ear canal at threshold
19. Minimum Audible Field (MAF):
• based on binaural (two ears) thresholds from loudspeakers
• –Measure sound pressure in sound field at head level
• -MAF thresholds tend to be 6 dB lower (better) than MAP thresholds due to binaural summation
20. Upper Limits of Hearing
• •Sounds become uncomfortably loud at a level of about 100 dB SLP
• –This level is fairly constant across frequencies
• •Sounds that evoke feeling or pain occur at levels of 120 – 140 dB SPL
• –Tactile sensations rather than auditory
21. Temporal Summation/Integration def
• -trading of duration and intensity
• -When sounds are shorter than approximately 300 ms, threshold (or loudness) depends on duration
22. Temporal Summation/Integration
• •As a sound gets shorter
• –Threshold becomes higher (less sensitivity)
• –The sound is perceived as being softer
• •As the sound get longer
• –Threshold becomes lower (better sensitivity)
• –The sound is perceived as being louder
23. integration
–a 10-fold decrease in duration is offset by a 10 dB increase in intensity
24. Just Noticeable Difference (JND) or Difference Limen (DL):
-the smallest perceptible difference between two sounds
25. Absolute Difference Limens:
• –ΔI: smallest intensity change that can be detected
• –ΔF: smallest frequency change that can be detected
• -they specify the absolute physical difference needed to tell two sounds apart
26. Relative Difference Limen or Weber Fraction:
27. -considers both the absolute DL and the starting point
• -Weber’s Fraction = absolute DL / starting point
• = ΔI/I or Δ F/F
28. Intensity Discrimination
• –Weber’s Fraction (ΔI/I) decreases slightly with increasing intensity
• – ΔI/I is about 0.4 near threshold and decreases to 0.2 at higher intensities
29. •Frequency Discrimination
• –Weber’s Fractions (ΔF/F) are relatively constant for mid-frequencies (600 – 2000 Hz)
• – ΔF/F is smallest (0.002) between 600 – 2000 Hz, and gets larger for frequencies above and below this range
30. Loudness:
31. our perception of intensity
• •Intensity is a physical attribute of sound
• •Loudness is a perceptual attribute of sound
32. Equal Loudness Contours or Phon Curves:
33. lines that connect equally loud stimulus levels at different frequencies
• •A way of quantifying loudness
• •How much
34. Phons:
• units of loudness defined relative to the loudness of a 1000 Hz tone
• –A 40 dB SPL tone at 1kHz has a loudness of 40 phons, a 50 dB SPL tone at 1kHz has a loudness of 50 phons, etc

•All sounds that are equal in phons have the same loudness level even though physical levels (dB) are different
35. Sone:
• another unit of loudness that shows the relationship between loudness and intensity
• •Sone scale compares the loudness of any intensity with the loudness of a specific reference sound
• –Reference = 1 sone = a 1000 Hz tone with an intensity of 40 dB SPL
36. Sone Scale
• Loudness (in sones) doubles for every 10 dB increase in intensity
• •Loudness (in sones) is halved for every 10 dB decrease in intensity
37. Steven’s Power Law:
38. The linear relationship between log loudness and log intensity corresponds to a power relationship between loudness and intensity (in raw units)
• Formula
• Loudness = k * Intensitye
39. Critical Bandwidth (CBW):
bandwidth at which a perceptual change occurs

• •Critical Bands are:
• –larger for higher frequencies
• –smaller for lower frequencies
40. Pitch:
• our perception of frequency
• •The lowest frequency pure tone that evokes a “tonal” pitch is 20 Hz
• •For a tone to sound “tonal”, it must have a minimum duration of at least 10 – 60 ms in duration depending on frequency
41. Mels:
• unit of pitch that parallels the sone unit of intensity
• •Mel scale relates frequency and pitch
• –Reference value

-ratio scale
42. Pitch of the Missing Fundamental:
43. perceived pitch corresponds to the fundamental frequency, even though the fundamental frequency is not physically present
 Author: cgray10 ID: 52319 Card Set: hearing exam6 Updated: 2010-11-30 05:36:54 Tags: hearing Folders: Description: exam 6 Show Answers: