Developing a model to explain and stimulate the perception of sounds in three dimensions
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Transcript of Developing a model to explain and stimulate the perception of sounds in three dimensions
Developing a model to explain and stimulate the perception
of sounds in three dimensions
David Kraljevich and Chris Dove
Experimental Goal
• Create a model describing how sound waves recorded at the position of the eardrum change depending on the location of their source.
• Test the model by attempting to synthesize “directional” sounds and evaluate them subjectively.
Sound, the Listener, and the Environment
• Pressure waves• Diffraction and
Reflection• Interference• Reverberation :
Direct Field vs. Indirect Field
From “A 3D Sound Primer” http://www.northwestern.edu/musicschool/classes/3D/pages/sndPrmGK.html#anchor509080
Pressure waves
Two researchers, Headphones, and a Brain:
Winter experimentsA sound arriving at the near ear is more intense and arrives earlier than the sound at the far ear.
• The speed of sound at room temperature and 1atm is 343 m/s
• At most, there will be a 0.7 to 0.8 ms difference between the time it takes to reach one ear and the other.
• We also predict that they will usually arrive at different phases.
Out of Phase Experiment
Right channel: slightly out of phase
Results: perceived sound coming from the right!
Soundforge 4.5. 60 Hz stereo. 44100 samples/sec
Zen Clock Experiment
1. Record “silence”
2. Record Bar Resonating
3. Spectral Analysis
http://www.serenityhealth.com/zclok_burg.html
Amplitude (dB) vs. time (samples)
Amplitude (dB) vs. Frequency (Hz) (FFT)
Signal vs Noise
Frequency spectrum of “silent” recording. Computed with a Fast Fourier Transform using 4096 samples. No smoothing windows applied. RMS power = -52.30 dB
silence
clock
Time-domain to frequency-domain
Spectrum of 6500Hz sine wave
Frequency spectra of piano and violin
Our Model
Will Include• Phase differences • Time differences• Intensity differences
May Include• Spectral differences
Won’t Include• Psychological
factors• Head movement• Moving sources• Environmental cues
-Reverberation
Spring Research
• Use of Binaural Head
• Deeper exploration of Fourier analysis
• Quantitative treatment of elevation