Professor Kreiman’s NIH-supported research, jointly
conducted with Bruce Gerratt, PhD in The Voice Perception Laboratory, focuses
on the perception (and secondarily on the production) of normal and
pathological voice. Voice quality is a primary means by which humans signal
their identity, internal state, and intentions to others, and voice disorders
can have devastating personal and professional consequences, creating an
undesirable personal image and making vocal communication difficult or
impossible. However, despite the importance of voice perception and large
literatures in disciplines ranging from music to medicine, little progress has
been made in understanding how listeners perceive voices. In fact, the modern
history of voice research may be viewed as a series of efforts to circumvent
the problem of measuring quality by substituting “objective” measures of
acoustics, physiological functions, or airflow. Unfortunately, objective
measures of quality are meaningless unless they are validated against
perceptual measures. Thus, perception of voice remains of central importance
even in efforts to eliminate perceptual measures.
Their research attempts to develop models of voice
perception and speaker recognition. Without such models, the goal of
understanding how listeners perceive voices will not be achieved. Initial
studies in the laboratory sought to specify the sources of variability in
listeners’ ratings of vocal quality. More recently, studies have focused on
developing reliable, valid methods to measure perceived vocal quality, by
controlling the factors underlying response variability. They have devised a
new, theoretically-motivated method of assessing quality – listener-mediated
analysis-resynthesis—in which listeners explicitly compare synthetic and
natural voice samples, and change speech synthesizer parameters to create
acceptable auditory matches to voice stimuli. This method is designed to
replace usable internal standards for qualities like breathiness and roughness
with externally presented stimuli. Initial results indicate that this technique
does control the major hypothetical sources of disagreement in rating scale judgments.
A reliable and valid method of measuring what listeners
hear is an essential component of a common theoretical framework that links
together physiology, aerodynamics, acoustics, and perception, to explain how
tissue movement finally results in the perception of speech sounds. However,
voice production, perception, and acoustics in the past have been studied as
nearly independent disciplines, with little cross-fertilization of ideas and
virtually no theory to link levels of description. A unified approach to the
study of voice could have many potential benefits, including theoretically
motivating surgeries to improved voice quality, allowing prediction of
post-surgical voice quality given a patient’s particular findings, motivating
objective measures of voice, specifying which aspects of a voice are essential
to its identification, and so on. Development of such a theory (in
collaboration with other faculty members in Head and Neck Surgery, Engineering,
and Linguistics) is the ultimate goal of this ongoing research.
- Kreiman J., Gerratt B.R., Khan S.U., “Effects of native language on perception of voice quality,” J Phon. 2010 Oct 1;38(4):588-93.
- Kreiman J., Antonanzas-Barroso N., Gerratt B.R., “Integrated software for analysis and synthesis of voice quality,” Behav Res Methods. 2010 Nov;42(4):1030-41.
- Kreiman J., Gerratt B.R., “Comparing two methods for reducing variability in voice quality measurements,” J Speech Lang Hear Res. 2011 Jun;54(3):803-12. Epub 2010 Nov 16.
- Kreiman J., Gerratt B.R., “Perceptual sensitivity to first harmonic amplitude in the voice source,” J Acoust Soc Am. 2010 Oct;128(4):2085-89.
- Kreiman J., Gerratt B.R., Ito M., “When and why listeners disagree in voice quality assessment tasks,” J Acoust Soc Am. 2007 Oct;122(4):2354-64.
- Kreiman J., Gerratt B.R., Antonanzas-Barroso N., “Measures of the glottal source spectrum,” J Speech Lang Hear Res. 2007 Jun;50(3):595-610.
- Kreiman J., Gerratt B.R., “Perception of aperiodicity in pathological voice,” J Acoust Soc Am. 2005 Apr;117(4 Pt 1):2201-11.
- Kreiman J., Gabelman B., Gerratt B.R., “Perception of vocal tremor,” J Speech Lang Hear Res. 2003 Feb;46(1):203-14.