Identifying sound sources

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Identifying sound sources

• Chapter 12 sensation and perception

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Auditory Scene Analysis

• How does the auditory system allow us to perceive
  and recognise many different sounds occurring at
  the same time?
• A bird chirping and a cat meowing at the same
  time - the combined signal (pressure wave) enters
  the ear
• Auditory scene - refers to the array of sounds
  in our environment
• Auditory scene analysis the process by which we
  separate the sounds into separate perceptions to
  allow us to recognise each of the sounds

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Auditory Scene Analysis

• Spatial location separate and recognise the
  individual sounds according to where each sound
  is coming from?
• Recording from a single speaker possible to
  hear the individual instruments?
• Cues that allow us to analyze the auditory scene
  Principles of Auditory Grouping

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Principles of Auditory Grouping

• Spatial location
• Similarity of timbre and pitch auditory stream
  segregation lab - also separate simultaneous
  talkers based on pitch and timbre of their voices
• Proximity in time Before stream segregation due
  to similarity of timbre or pitch can occur, tones
  with similar timbres or frequencies have to occur
  close together in time. See figure 12.16 and
  explanation lab demonstration

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Principles of Auditory Grouping

• Good continuation see lab on tone bursts with
  gaps of silence vs. noise figure 12.20
• Experience e.g. melody schema
• Together, these principles of auditory grouping
  provide information about the number and identity
  of sound sources in the environment. One alone is
  not sufficient.

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Hearing inside rooms

• How our perception of sound is influenced by the
  properties of our listening environments
  (outside, inside, room size etc)
• Direct sound
• Indirect sound
• even though reflections from surfaces enable us
  to receive a sequence of sounds coming from many
  directions, we generally perceive the sound as
  coming from only one location.

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Perceiving 2 sounds that reach the ears at
different times

• Fusion
• Precedence effect (1-5ms)
• Echo threshold (gt5ms) depends on relative level
  and duration