APPLICATION

Suprathreshold Discrimination (ACC)

Using the acoustic change complex to show objectively that audible speech cues can be told apart.

What the cortical response shows

  • A present change response confirms the auditory system registered the change; an absent one suggests the contrast is not being resolved, even if the sound is audible.[10]
0100200300400latency (ms)Change response (ACC)
A change within an ongoing sound — of pitch, level or spectrum — evokes a second onset-like response. Its presence proves the change was discriminated, not merely detected.

Why the cortical response here

  • Detecting sound is not the same as telling speech cues apart; the acoustic change complex provides an objective index of discrimination.[8]
  • The ACC is elicited by both spectral and intensity changes, so it can probe the very contrasts that carry speech information.[9]

How it changes management

  • The ACC helps move objective testing beyond audibility toward aidability — whether a device delivers distinguishable, not just detectable, speech.[10]

TEACHING POINT

The acoustic change complex answers a question thresholds cannot: not 'can they hear it?' but 'can they tell it apart?'.[8]

Sources for this page are listed on the References page. Browse all applications from the atlas home.