Animals hear different worlds
Humans hear 20 ans 15k hz
Sounds above are ultrasound
Sounds below are known as intrasound, used by elephants and whales to comm. long distant

The Sound Stimulus

Collision of molecules taking place in gas, solid, liquid.

• waves
• amp and wave length
• amp - loudness
• wave - pitch
• human auditory
  • percicve auditory ssensitivity of 10 billion
  • we use logrithmic scale cause dB
    • The sound energy of a vacuum cleaner (80 dB) is ten times more intense than the sound energy of busy street traffic (70 dB).
• 60/60 rule, 60 dB or lower, less than 60 min of listening a day

The Ear

Outer to middle to inner

• Innter (transduction begins)
• Cochlea transduces sound into neural data

Cochlea

• Hair cells and Basilar Membrane
  • Basiklar Membrane
    • Whip like movement senz hair cells
    • amount of movement is based around pitch
    • max displacement is high pitch
    • apex is wide and floppy
    • displacement there is low frequency

Transduction in Hair cells

• Not muh movement for response
• When potassium channel open,s it enters hair cells, triggers high of calcium, increased relase of futament

Auditory Pathways

Auditory Cortex

Lower freq. sounds are processed rostrally
high, caudally

• rimary auditory cortec (A1)
• Secondary processes complex, like speech

Equal loudness contours

• Part. hear 1k hz tone, E63 pitch
• 100 hz tone has to be 60db, or 100 times louder, than 1000 at 40, before they seem as loud
• sensitive to range of spoken language

SOund localization

• Arrivl times of sounds of the two ears
• before right than left, we percieve as right

McGurk Illiusion

• see one thing, hear another
• say baba, lips, gaga, hear da-da

Disorders of hearing

• Some hearing loss is normal
• lose sensitivity to higher pitches first
• should take seriously, cna lead to dementia
• can be peripheral, damage to hair cell, problems with circuluation
• can be central, such as stroke
• source determins treatment, like cochlear implant or hearing aid