Sensing Vibrations. Basilar membrane measures the amplitude and frequency of sound waves –amplitude (loudness) - magnitude of displacement of the basilar.

Sensing Vibrations

Sensing Vibrations

• Basilar membrane measures the amplitude and frequency of sound waves

– amplitude (loudness) - magnitude of displacement of the basilar membrane

–frequency (pitch) - frequency and location of displacements of the basilar membrane

Sensing Vibrations

• Basilar membrane measures the amplitude and frequency of sound waves

–frequency (pitch) - frequency and location of displacements of the basilar membrane

Sensing Vibrations

• Bundles of “hair cells” are embedded in basilar membrane

Sensing Vibrations

• When hair cells sway back and forth, they let charges inside

• This flow of charges is converted to action potentials and sent along the auditory pathway

The Auditory Pathway

• The auditory pathway is complex and involves several “stations” along the way to the auditory cortex in the brain

• Lots of processing must be done in real-time on auditory signals!

How Can You Localize Sound?

• Ponder this:– Imagine digging two trenches in the sand beside a

lake so that water can flow into them. Now imagine hanging a piece of cloth in the water in each trench. Your job is to determine the number and location and type of every fish, duck, person, boat, etc. simply by examining the motion of the cloth. That’s what your auditory system does!

- Al Bregman

How do we Stay Balanced?

The Vestibular System

Vestibular System (Balance)

Vestibular System (Balance)

Vestibular System (Balance)

Vestibular System (Balance)

Head accelerates this way

Cupula getspushed

Fluid goes this way

Vestibular System (Balance)

Head accelerates this way

Cupula getspushed

Fluid goes this way

Vestibular System (Balance)

• movement of the cupula is detected by hair cells

• hair cells in the vestibular system are more sensitive than hair cells on the basilar membrane!

Vestibular, Visual, and Proprioceptive Systems Work Together

• Try standing on one foot with your eyes closed!

Fun Facts about The Vestibular System

• Seasickness arises when the vestibular system and the visual system send conflicting information

Fun Facts about The Vestibular System

• Seasickness arises when the vestibular system and the visual system send conflicting information

• People can be knocked down by moving walls!

Fun Facts about The Vestibular System

• Seasickness arises when the vestibular system and the visual system send conflicting information

• People can be knocked down by moving walls!• Alcohol causes the spins by (among other things)

changing the density of the fluid in the semicircular canals