Joshua M. Alexander

Biography

Joshua M. Alexander received his Ph.D. in Audiology (psychoacoustics) and post-doctoral training in speech perception at the University of Wisconsin- Madison. Before coming to Purdue, he completed both clinical and post-doctoral fellowships at Boys Town National Research Hospital in Omaha, Nebraska. Research interests focus on auditory processes contributing to speech perception deficits in hearing-impaired listeners and signal processing techniques to overcome them. Ongoing projects include work on frequency-lowering techniques, wide dynamic range compression, and speech enhancement techniques. In 2015, Dr. Alexander was issued a US patent for his novel method of frequency lowering. He has another pending on a technique for speech enhancement. Discovery is aided by an innovative approach by which signal processing techniques like these and realistic hearing aid amplification are simulated in the laboratory on a PC. This allows the researchers in the lab to know precisely the effect that their manipulations have on the acoustic signal as they try to relate listener performance back to psychophysical estimates of cochlear filtering, auditory nerve models, and cognitive processing. The framework guiding the discovery process involves the interplay of three key components: basic research (speech perception and psychoacoustic deficits); applied research (digital signal processing algorithms intended for hearing aids and automatic speech recognition); and modeling. Ongoing efforts encompass two main lines of research: understanding existing technology and developing new technology. Recently, effort has been directed towards developing auditory nerve models that quantify information in a speech signal to help explain the effects that different signal processing strategies have on speech perception as a function of hearing loss so that better solutions can be devised.

Research Interest

auditory processes contributing to speech perception deficits in hearing-impaired listeners and signal processing techniques to overcome them