What is sound?
Sound refers to pressure waves generated by vibrating air molecules
Physical aspects of sound
Air- 340 m/s Water- 1500m/s Glass- 5300m/s Light- Air- 300,000 km/s
Sensitivity to sound- amplitude
Using the magnitude estimation method, subjects report perception of loudness function to the sounds physical intensity expressed as a proportion of sound intensity. (40 DB sound pressure level- SPL)
Sensitivity to sound- frequency
Human audible spectrum ranges from 20 to 20,000 HZ
- the sensitivity is greatest in the range of 500 to 5000HZ.
- small animals generally hear higher frequencies, because of cochlea or small animals is smaller and resonates better at high frequencies
Sensitivity to sound- pitch and timbre perception
Pitch: property or auditory sensation regarding sound may be offered from their musical scale (low to high). It closely relates to physical properties or fundamental frequency.
Timber- when two tones have the same loudness, pitch, duration but sounds different
Sound waves and complexity
Frequency- (pitch) nb cycles per second hertz
Amplitude- (loudness) sound pressure level: DECIBEL (db)
A relative unit defined by the sensitivity of human hearing- OdB~ 2.10-5 pascal (newtons m-2) unit of pressure.
Sounds that consist of sine wave are known as pure tones.
Sound complexity- most sounds = complexes made up of one frequency and several harmonies of the fundamental.
Sound legislation 1- binimaurql cues
- azimuth- elevation
- neurone in the medical supervisor olive ( MSO) com location of sound by acting coincide detectors.
- the systematic variation delay lengths/ lines are two impute that work effectively to create a map of sound.
- neutron E would be most sensitive to sound
- sounds have high levels of intensity
Auditory system- outer, middle and inner ear
Outer ear- gathers sound
• pinnacle, tympanic membrane
Middle ear- mechanical transformer
• ossicles, malleus, incus, stapes, footplate connected to the oval window
Inner ear- where auditory receptors are located
• semicircular canld, vestibule, cochlea
How do we capture sound
High frequency- greatest vibration near membrane
Base and low frequency- greatest vibration near the ape
The basilar membrane has a frequency to place conversion for pure tone stimuli
Organ of corti
- the inner ears receptor= the organ of Corti
- corti contains 16000 hair cells in four rows. A single Raw of the inner ear and the three in the outer hair cells
- afferent axons to cochlear nucleus end on inner hair cells.
- efferent axons largely innervate outer hair cells

Auditory system two- hair cells, transduction and cochlear amplifier
- hair cells transform mechanical energy into neural signal
- The displacement of the stereocilia open K + channels. FaceTime opens CA + + channels in the cell space which causes neurotransmitter release to excites axons whoar cell bodies are in the spiral or cochlear ganglion
