1. Human hearing Limits, the human ear, and issues of perception
Phys1061, S.Boyd

2. Physical Characteristics
Human hearing
Physical Characteristics
Frequency range: 20 Hz … 20 kHz
Factor of 1000
Intensity range: to 1 W/m2
Factor of 1012
Filtering of information
Phys1061, S.Boyd

3. Physical characteristics
Human hearing
Physical characteristics
Graphics: Rossing, Moore & Wheeler, The Science of Sound, 3rd Ed.
Phys1061, S.Boyd

4. Human hearing
Psychophysics:
objective and quantitative study of the relation of physical stimuli and sensory perceptions
Middle Ear:
Transformation into mechanical and then electrical signals
Processing:
sorting, selection,
recognition
Pressure fluctuations
Phys1061, S.Boyd

5. Structure of the human ear
Human hearing
Structure of the human ear
Phys1061, S.Boyd

6. Important parts of the ear
Human hearing
Important parts of the ear
Outer Ear:
Auditory canal
Ear drum
Middle ear:
Ossicles: hammer (malleus), anvil (incus), stirrup (stapes)
Inner Ear
Cochlea
Auditory nerve
Phys1061, S.Boyd

7. Important parts of the Cochlea
Human hearing
Important parts of the Cochlea
Oval window
Scala vestibuli (filled with fluid)
Scala timpani
Round window
Basiliar membrane
Organ of Corti
Auditory nerve
Phys1061, S.Boyd

8. Mechanism of signal transport
Human hearing
Mechanism of signal transport
Hall, Musical Acoustics, 3rd Ed.
Phys1061, S.Boyd

9. Lever action of ossicles
Small displacement over large area becomes large displacement over small area

10. Hearing loss
Conduction deafness: reduced mobility of ossicles due to vibrous tissue (i. e. from repeated otitis)
Nerve deafness: deterioration of hair cells or nerve (also age-related presbycusis)
Can be distinguished through bone conduction

11. Just noticable differences
At which frequency difference do two tones sound different to us?
200/201 Hz
200/202 Hz
200/203 Hz
2000/2002 Hz
2000/2003 Hz
2000/2004 Hz
2000/2006 Hz
2000/2008 Hz
2000/2002 Hz
2000/2003 Hz
2000/2004 Hz
2000/2006 Hz
2000/2008 Hz

12. Simultaneous sounds
At which difference in frequency can we hear two distinct sounds?
1000 Hz combined with …
700 Hz
800 Hz
900 Hz
990 Hz
1010 Hz
1100 Hz
1200 Hz
1300 Hz
980 Hz
1020 Hz
950 Hz
1050 Hz

13. How are sounds resolved?

14. How are sounds resolved?
Critical band: region on basiliar membrane for reception of a pure tone
If critical bands overlap, only a single tone is heard
The critical band is larger at low frequencies.