CHAPTER 10PSYCHOACOUSTICSThreshold or LimenMinimum Audibility Curve--Slide 5Auditory Response AreaDifferential SensitivityWeber’s Law--A Theory of human differential sensitivityFrequency ResolutionGood Frequency Resolution Allows you to:Brief Sounds: Temporal IntegrationTemporal Aspects: TEMPORAL INTEGRATIONCHAPTER 10Auditory SensitivityPSYCHOACOUSTICS•A branch of psychophysicsThe study of the relation between: •the physical aspects of sound and •the psychological experience of soundThreshold or Limen•Absolute Threshold -- lowest value of stimulus which can be detected•Difference Threshold -- smallest detectable change in a stimulus•These 2 Thresholds were the primary questions in CLASSICAL PSYCHOPHYSICSThresholdsMinimum Audibility Curve--•Plot of threshold of detection (in dB SPL) as a function of frequency•Lowest thresholds in 1 to 4 kHz regionThresholdsThe Auditory Response AreaThresholdsAuditory Response Area•Range of useable hearing-- from threshold of detection to threshold of feeling/pain•Also called the DYNAMIC RANGE OF HEARINGThresholdsDifferential Sensitivity•Detecting changes in a stimulus•(e.g., how small a change in frequency can you detect)•Measured as the jnd - just noticeable differenceDiff. Sensitivity//Weber’s LawWeber’s Law--A Theory of human differential sensitivity• Δ S/S = k•Size of jnd = constant fraction of the stimulus you start with•It’s easier to detect small changes in a stimulus if it had a small value to begin with.Diff. Sensitivity//Weber’s LawFrequency Resolution•The Critical Band reflects “internal filtering”--the ability to attend to a narrow range of frequencies•Remember the tuning curves from Bekesy’s dead ear and the healthy cochlea?•You need the healthy cochlea to have good frequency resolving powerGood Frequency Resolution Allows you to:•Listen to harmonic structure of complex signals•Detect Shifts in Frequency (esp. formant transitions)•Hear and Understand signals in noiseBrief Sounds: Temporal IntegrationTemporal IntegrationTemporal Aspects: TEMPORAL INTEGRATION •A certain amount of energy must be present for detection of a brief signal.•The process of summing energy over time is called integration and it is completed by 300 ms.•If the signal is shorter than 300 ms, then power must be increased for the signal to be detected. Temporal