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Auditory Motion II

Auditory Motion II. Or how I learned to stop worrying and love collisions. Potential Sources of Information for Auditory Motion. Spectral content High frequencies more easily attenuated than low frequencies Tau varies across frequency

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Auditory Motion II

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  1. Auditory Motion II Or how I learned to stop worrying and love collisions

  2. Potential Sources of Information for Auditory Motion • Spectral content • High frequencies more easily attenuated than low frequencies • Tau varies across frequency • Relative change in spectral content across the hearing spectrum • Exponential increase in high frequencies during approach • Döppler Shift • Phenomenal change in pitch over time • Relative distance between sound waves decreases for an approaching object • Fairly constant rise in pitch • Dramatic change near listener, little change over approach • Interaural position***(Where we left off) • Objects farther in distance tend to be less lateralized • Change in lateralization over passage

  3. How do we perceive auditory TTA? • Potential Information • Tau-Intensity, Doppler shift, or ITD • Paradigms • Judge moment of passage (Rosenblum et al., 1987) • Simulate a racetrack, button press at passage point • Compare which of two sound sources traveled farther (Lutfi & Wang, 1999) • Speed Dependent results • Slow-moderate (less than 80 km/h) • Intensity most salient • Fast speed • Doppler shift • All cues contribute to judgments, relative contribution varies

  4. What is the influence of frequency on TTA perception? • Judge the terminal characteristic of a sound source (Neuhoff, 1999) • Exp. Rising/Falling intensity sound (Demo) • Exp. Rising/Falling Pitch sound (Demo) • Match terminal sound to standard • Accurate Falling; Biased Rising • Sensitivity to approaching sound characteristics • Harmonic tones • Compare bias with Harmonic Tone vs. Noise • No bias with Noise, only with tone • Less sensitivity to broadband TTA • Rhesus Monkeys also sensitive to rising tones • Supports detection of tau using intensity • Innate ability for judgment

  5. What about acoustic Spectrum? • Relative rate of attenuation across frequencies varies • Is there a ‘sweet spot’ for spectral change/exponent? • Are human better at a specific frequency range?

  6. Is there a contribution of spectrum? 20000 – 15000 – 10000 – 5000 – 0 – Frequency (Hz) | | | | | | 10 8 6 4 2 0 Time-to-Arrival for a Listener (sec)

  7. Spectral TTA • Test: Listeners judge TTA for eight 1-octave noise bands (Gordon et al., 2004) • 40-80 Hz; 80-160 Hz; …10,000-20,000Hz • Spectral bands differ in frequency and exponent slope (Demo bands) • Independent manipulations of exponents, spectral bands • Both the exponent and band contribute to judgments • Frequency has strongest influence • More underestimation at high freq

  8. Why does frequency bias responses? • Relative appearance of high frequencies in TTA • Closer sounds are higher in frequency • Evolutionary bias for frequency cue? • Other cues for proximal sound source • Higher intensity • Ripple noise pitch distortion • Timbrel dissonance • All cues for proximal sound sources correlate with perceived urgency • Urgency: need to respond • Subjective correlation: 1 – 100 scale of urgency • Response time: faster reaction to more urgent sounds

  9. Goals in Acoustic Design • Improve speech communication • Acoustic Structure to facilitate speech • Classroom; concert hall • Noise elimination • Algorithms for gain control • Noise isolation from signal • Non-visual warning systems • Alarms for urgency • Train horn; fire alarm • Actions cues for non-invasive guidance • Auticons; cross-walk signals • Auditory spatial displays • Visual enhancement cues • Blind-user interface; Cockpit display

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