The [ Select ] is made up of cartilage and its job is to "catch" sound waves and pass them down the [ Select ] . The sound waves push back and forth on the [ Select ] , setting it into vibration. This structure is connected to three tiny bones (the ossicles), which are then also set into motion. The last bone (the stapes) is connected to the cochlea via the oval window. Inside the cochlea is the [ Select ] , which is "tuned" to vibrate at different frequencies along its length. Connected to this structure is the [ Select ] , which is home to hair cells that when activated send a signal to the auditory nerve that travels up to the auditory cortex.