Communications Biophysics

Contains research objectives and reports on six research projects split into three sections.National Institutes of Health (Grant 5 P01 NS13126-07)National Institutes of Health (Training Grant 5 T32 NS07047-05)National Institutes of Health (Training Grant 2 T32 NS07047-06)National Science Foundation (Grant BNS 77-16861)National Institutes of Health (Grant 5 R01 NS1284606)National Institutes of Health (Grant 5 T32 NS07099)National Science Foundation (Grant BNS77-21751)National Institutes of Health (Grant 5 R01 NS14092-04)Gallaudet College SubcontractKarmazin Foundation through the Council for the Arts at M.I.T.National Institutes of Health (Grant 1 R01 NS1691701A1)National Institutes of Health (Grant 5 R01 NS11080-06)National Institutes of Health (Grant GM-21189

The neural representation and behavioral detection of frequency modulation

Understanding a speech signal is reliant on the ability of the auditory system to accurately encode rapidly changing spectral and temporal cues over time. Evidence from behavioral studies in humans suggests that relatively poor temporal fine structure (TFS) encoding ability is correlated with poorer performance on speech understanding tasks in quiet and in noise. Electroencephalography, including measurement of the frequency-following response, has been used to assess the human central auditory nervous system’s ability to encode temporal patterns in steady-state and dynamic tonal stimuli and short syllables. To date, the FFR has been used to investigate the accuracy of phase-locked auditory encoding of various stimuli, however, no study has demonstrated an FFR evoked by dynamic TFS contained in the modulating frequency content of a carrier tone. Furthermore, the relationship between a physiological representation of TFS encoding and either behavioral perception or speech-in-noise understanding has not been studied. The present study investigated the feasibility of eliciting FFRs in young, normal-hearing listeners using frequency-modulated (FM) tones, which contain TFS. Brainstem responses were compared to the behavioral detection of frequency modulation as well as speech-in-noise understanding. FFRs in response to FM tones were obtained from all listeners, indicating a reliable measurement of TFS encoding within the brainstem. FFRs were more accurate at lower carrier frequencies and at shallower FM depths. FM detection ability was consistent with previously reported findings in normal-hearing listeners. In the present study, however, FFR accuracy was not predictive of behavioral performance. Additionally, FFR accuracy was not predictive of speech-in-noise understanding. Further investigation of brainstem encoding of TFS may reveal a stronger brain-behavior relationship across an age continuum

Communications Biophysics

Contains reports on four research projects.National Institutes of Health (Grant 5 P01 NS13126-02)National Institutes of Health (Grant 5 K04 NS00113-03)National Institutes of Health (Grant 2 ROI NS11153-02A1)National Science Foundation (Grant BNS77-16861)National Institutes of Health (Grant 5 RO1 NS10916-03)National Institutes of Health (Fellowship 1 F32 NS05327)National Institutes of Health (Grant 5 ROI NS12846-02)National Institutes of Health (Fellowship 1 F32 NS05266)Edith E. Sturgis FoundationNational Institutes of Health (Grant 1 R01 NS11680-01)National Institutes of Health (Grant 2 RO1 NS11080-04)National Institutes of Health (Grant 5 T32 GIM107301-03)National Institutes of Health (Grant 5 TOI GM01555-10

The Kingdom, the power, and the glory

None provided

A Computational Model of the Cognition of Tonality

Tonality is the organization of pitches, both simultaneously and across time, so that certain pitches and chords are heard as attracted, in varying degrees, to other pitches and chords. Most art music from the seventeenth to the nineteenth centuries, and popular music to the present day, is heavily steeped in a musical language that makes use of tonality to define a ‘central’ most attractive pitch or chord called the tonic. It is widely thought that the feelings of expectancy and resolution induced by movements towards and away from the tonic allow composers to imbue tonal music with meaning and emotion. In this dissertation, I identify and model some of the innate processes by which feelings of tension, resolution, stability, and so forth, are induced by successions of pitches and chords, irrespective of their harmonic consonance. By innate, I mean processes that do not require the learning of a musical corpus—such processes are important because they provide explanations for why tonal music, and our cognition of it, take the specific forms they do. To do this, I introduce a novel family of mathematical methods—metrics applied to expectation tensors—for calculating the similarity of pitch collections. Importantly, such tensors can represent not just the notated pitches of tones, but also their spectral pitches (their harmonics). I then demonstrate how these techniques can be used to model participants’ ratings of the fits of tones in microtonal melodies, and the fits of all twelve chromatic pitches to an established key centre (Krumhansl’s probe tone data). The techniques can also be generalized to predict the tonics of any arbitrarily chosen scale—even scales with unfamiliar tunings. In summary, I demonstrate that psychoacoustic processes, which are innate and universal, play an important role in our cognition of tonality