1 research outputs found
Periodicity Pitch Detection in Complex Harmonies on EEG Timeline Data
An acoustic stimulus, e.g., a musical harmony, is transformed in a highly
non-linear way during the hearing process in ear and brain. We study this by
comparing the frequency spectrum of an input stimulus and its response spectrum
in the auditory processing stream using the frequency following response (FFR).
Using electroencephalography (EEG), we investigate whether the periodicity
pitches of complex harmonies (which are related to their missing fundamentals)
are added in the auditory brainstem by analyzing the FFR. While other
experiments focus on common musical harmonies like the major and the minor
triad and dyads, we also consider the suspended chord. The suspended chord
causes tension foreign to the common triads and therefore holds a special role
among the triads.
While watching a muted nature documentary, the participants hear synthesized
classic piano triads and single tones with a duration of 300ms for the stimulus
and 100ms interstimulus interval. We acquired EEG data of 64 electrodes with a
sampling rate of 5kHz to get a detailed enough resolution of the perception
process in the human brain.
Applying a fast Fourier transformation (FFT) on the EEG response, starting
50ms after stimulus onset, the evaluation of the frequency spectra shows that
the periodicity pitch frequencies calculated beforehand +/-3Hz occur with some
accuracy. However, jitter turned out as a problem here. Note that the
sought-for periodicity pitch frequencies do not physically exist in the
frequency spectra of the stimuli.Comment: 10 pages, 4 figures, 2 table