Humans must process fleeting auditory information in real time, such as speech and music. The amplitude modulation of the acoustic waveforms of speech and music is rhythmically organized in time, following, for example, the beats of music or the syllables of speech, and this property enables temporal prediction and proactive perceptual optimization. At the neural level, external rhythmic sensory input entrains internal neural oscillatory activities, including low-frequency (e.g., delta, 1-4 Hz) phase, high-frequency (e.g., beta, 15-25 Hz) power, and their phase-amplitude coupling. These neural entrainment activities represent internal temporal prediction and proactive perceptual optimization. The present thesis investigated two critical but previously unsolved questions. First, do these multiple entrainment mechanisms for tracking auditory rhythm have distinct but coordinated perceptual functions? Second, does regularity in the temporal (when) domain associate with prediction and perception in the orthogonal spectral (what) domain of audition? This thesis addressed these topics by combining electroencephalography (EEG), psychophysics, and statistical modeling approaches. Chapter II shows that beta power entrainment reflects both rhythmic temporal prediction (when events are expected) and violation of spectral information prediction (what events are expected). Chapter III further demonstrates that degree of beta power entrainment prior to a pitch change reflects how well an upcoming pitch change
will be predicted. Chapter IV reveals that rhythmic organization of sensory input proactively facilitates pitch perception. Trial-by-trial behavioural-neural associations suggested that delta phase entrainment reflects temporal expectation, beta power entrainment reflects temporal attention, and their phase-amplitude coupling reflects the alignment of these two perceptual mechanisms and is associated with auditory-motor communication. Together, this thesis advanced our understanding of how neural entrainment mechanisms relate to perceptual functions for tracking auditory events in time, which are essential for perceiving speech and music. / Thesis / Doctor of Science (PhD) / Perceiving speech and musical sounds in real time is challenging, because they occur in rapid succession and each sound masks the previous one. Rhythmic timing regularities (e.g., musical beats, speech syllable onsets) may greatly aid in overcoming this challenge, because timing regularity enables the brain to make temporal predictions and, thereby, anticipatorily prepare for perceiving upcoming sounds. This thesis investigated the perceptual and neural mechanisms for tracking auditory rhythm and enhancing perception. Perceptually, rhythmic regularity in streams of tones facilitates pitch perception. Neurally, multiple neural oscillatory activities (high-frequency power, low-frequency phase, and their coupling) track auditory inputs, and they are associated with distinct perceptual mechanisms (enhancing sensitivity or decreasing reaction time), and these mechanisms are coordinated to proactively track rhythmic regularity and enhance audition. The findings start the discussion of answering how the human brain is able to process and understand the information in rapid speech and musical streams.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/24860 |
| Date | January 2019 |
| Creators | Chang, Andrew |
| Contributors | Trainor, Laurel, Psychology |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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