mod4

• Harmonic Spectrum


  Measured frequencies as integers in Hertz
• Missing Fundamental Effect


  Imagined perception of absent frequencies alongside present ones
• Timbre


  Psychological sensation combining sound frequency and harmonic spectrum
• Onset and offset of sounds

  Alter sound quality
• Interaural level difference


  Sounds from one side perceived louder by the corresponding ear
• Interaural Time Difference


  Sound reaching one ear before the other
• Cone of confusion


  Area making sound localization difficult
• Elevation Perception


  Vertical sound source localization
• Reverberation and Echo


  Delayed sound reflections
• Sound frequency and travel distance

  Amplitude reduction at 1/(distance)² rate
• Echo


  Sound reflections arriving 40-50 ms after the initial sound
• Auditory Scene Analysis


  Process of segregating sounds spatially, temporally, and spectrally
• Spatial segregation


  Separating sounds by perceived location
• Temporal segregation


  Separating sounds by chronological order
• Spectral segregation


  Grouping sounds by frequency
• Spectral Sensitivity


  Efficiency in detecting sound frequencies
• Sound restoration


  Brain reconstructing fragmented sounds
• Roles of vestibular information in our daily life

  • Vestibulo-spinal reflex (balance and postural control)
  • Vestibulo-Ocular Response (visual stability)
  • Vestibulo-autonomic reflex (regulation of blood pressure)
• Vestibular System


  Provides information about balance and spatial orientation
• Vestibular organs and sensitivity to changes

  • Anterior semicircular canal
  • Posterior semicircular canal
  • Horizontal semicircular canal
• Vestibular organs


  • Senses rotational movements
  • Utricle and Saccule (otolith organs) sense linear acceleration and gravity
• How vestibular organs work when the head is moving (and when the head is not moving)

  1. Resting State - head not moving, stereocilia are not bent

  2. Head movement causes stereocilia to bend

  3. Depolarization (Excitation) - observed when stereocilia bend in the direction of kinocilium

  4. Hyperpolarization (Inhibition) - observed when stereocilia bend in opposite direction of kinocilium
• Otolith organs


  Sense linear acceleration and gravity
• Utricles


  • Contains 30,000 hair cells that detect changes along the horizontal plane
• Saccules


  • Contains 15,000 hair cells that detect changes along the vertical plane
• Otoconia


  • Crystalline surface on top of a gelatinous layer, displaced by linear acceleration and gravity
• Striola


  • Band which determines direction of the kinocilium
• Hair cells


  • Embedded in gelatinous layer
• Semicircular Canals


  • Senses rotational movements
  • Three semicircular canals: anterior, posterior, and horizontal
• Ampulla


  • One per canal, contains a cupula (gelatinous membrane)
• Cupula


  • Has hair cells on its bottom (~7000) involved in transduction of neural signals