Learning Complex Auditory Categories

Carnegie Mellon University, Pittsburgh PA

Investigators

Abstract

With National Science Foundation support, Dr. Lori Holt, Dr. Andrew Lotto, and Dr. Randy Diehl will collaboratively investigate the basic perceptual and cognitive processes that underlie complex auditory categorization, such as phonetic categorization. One of the goals of the project is to develop efficient and robust L2 training techniques. In order to accomplish this, it is important to understand how the auditory system deals with variability in the input to create useful categories. With prior NSF support, the PIs have developed a methodology for training listeners to categorize novel non-speech sounds that have some of the same complexity as speech sounds. This approach allows the researcher to have complete control of listeners' experience and provides a view of category learning as it is happening. In this project, this methodology will be applied specifically to study the problem of feature determination and weighting in categorization. Results from these studies will be analyzed within a Bayesian statistical decision framework, which provides a means to compute how an "ideal observer" would perform in the task. Thus, it is possible to determine if listeners are performing optimally and, if not, discover what biases they exhibit in weighting strategies. Based on the results of these methodologies, training regimens for L2 category learning will be created and tested by training adult Japanese listeners on English /l/-/r/. In addition to the broader impact derived from a better understanding of auditory categorization and improved L2 training techniques, this project will develop techniques that may be useful for therapy with new users of hearing aids or cochlear implants. This program of research also provides a unique training opportunity for students. The three laboratories involved are connected to world-class experimental groups with different emphases (perceptual systems, cognitive neuroscience, audition and communication disorders). This inter-disciplinary setting will provide substantial interdisciplinary interaction for students.