About

I am a researcher in audio signal processing and musical acoustics. My current work focuses on statistical time-frequency analysis of reverberant audio, particularly instrumental vibrato. In addition to my research activities, I lead an undergraduate research class, advising a wide variety of projects in acoustics.

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Research Interests

Instrumental Vibrato Analysis

Musical vibrato is characterized by quasi periodic pitch modulation which is added to the note for expressive effect. Studying performers' vibrato provides an insight into both their technique and musical identities. Furthermore, as a modulated signal, vibrato provides a useful mechanism for investigating acoustic spaces.

Instantaneous Frequency Tracking

Instantaneous frequency tracking extends traditional pitch tracking to independently analyze the constituent partials of a musical note. However, for reverberant sounds, the acoustic space significantly impacts the recorded instantaneous frequencies. While these effects have been observed many times, more modelling is necessary in order to leverage these features in audio applications.

Pitch Shifting of Reverberant Audio

There are many applications where it is necessary to shift the pitch of a recorded sound. However, many of the existing algorithms suffer when the original sound contains significant reverberation. Our work aims to leverage the instantaneous frequency deviations or the initial recording in order to preserve a natural reverberation in the shifted sound.

Characterization of Acoustics Systems

The relationship between instantaneous frequency deviations in reverberant audio and statistical properties of the corresponding impulse response motivates the use of instantaneous frequency as a metric for characterizing acoustic systems. Future work in this area aims to use data from recorded natural sounds to estimate the decay time of a space in multiple frequency bands.

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Publications

Journal Papers

Zhang, Mingfeng, Hengwei Lu, Gang Ren, Sarah Smith, James Beauchamp, and Mark F. Bocko. "A Matlab-Based Signal Processing Toolbox for the Characterization and Analysis of Musical Vibrato." Journal of the Audio Engineering Society 65.5 (2017): 408-422.

Manuscript Reviewed Confrence Proceedings

Smith, Sarah R., and Mark F. Bocko. "Modeling the Effects of Rooms on Frequency Modulated Tones." Audio Engineering Society Convention 143. Audio Engineering Society, 2017. (PDF)

Smith, Sarah R., and Mark F. Bocko. "Preserving Reverberation in a Sinusoidally Modeled Pitch Shifter." Audio Engineering Society Convention 141. Audio Engineering Society, 2016. (PDF)

Smith, Sarah R., and Mark F. Bocko. "Effect of Reverberation on Overtone Correlations in Speech and Music." Audio Engineering Society Convention 139. Audio Engineering Society, 2015. (PDF)

Abstract Reviewed Conference Presentations

Smith, Sarah R., and Mark F. Bocko. "A Statistical Metric for Stability in Instrumental Vibrato." Audio Engineering Society Convention 145. Audio Engineering Society, 2018. (PDF)

Smith, Sarah R., and Mark F. Bocko. "A model for the observed decorrelation of partials in the overtone spectra of bowed stringed instruments." The Journal of the Acoustical Society of America 141.5 (2017): 3723-3723.

Smith, Sarah R., and Mark F. Bocko. "Impact of acoustic resonances on overtone correlations across a large musical instrumental database." The Journal of the Acoustical Society of America 138.3 (2015): 1936-1936.

Smith, Sarah R., and Mark F. Bocko. "Effect of reverberation on instrumental vibrato tones." The Journal of the Acoustical Society of America 137.4 (2015): 2437-2437.

Zhang, Minhao, Mingfeng Zhang, Sarah Smith, and Mark Bocko. "Real-time visualization of musical vibrato for music pedagogy." The Journal of the Acoustical Society of America 137.4 (2015): 2404-2404.

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Teaching

Throughout my graduate studies, I have served as a teaching assistant in both laboratory and classroom settings. Since 2016, I have also developed and led a project based acoustics course for upper level students in the audio and music engineering major.

Courses

Courses Designed

Acoustics Portfolio

Courses Assisted

Musical Acoustics
Introduction to Audio and Music Engineering
Fundamentals of Audio and Music Engineering, Part 1
ECE Math Workshop
Circuits and Microcontrollers for Engineers and Scientists

Sample Project Areas

Loudspeker enclosure designs and compensation
Design and measurement of room acoustics
Speech intelligibility in lecture halls
Musical instrument analysis
Computational modelling of room acoustics
Electromechanical reverberation effects
Noise isolation and masking