Robust estimation of synchronized spontaneous otoacoustic emission via singular value decomposition and optimal shrinkage.

We investigate matrix signal processing techniques for estimating synchronized spontaneous otoacoustic emission (OAE) in noise. Responses to repeated clicks are first stored in a matrix, and singular value decomposition is either applied in the time domain or the frequency domain after constructing a Hankel matrix at every frequency. The singular values are subject to optimal shrinkage (OS) which maximizes the signal-to-noise ratio. Human OAE data were analyzed, and the Hankel matrix method outperforms the time-domain OS method in synchronized spontaneous otoacoustic emission estimation, but not in the estimation of transient-evoked otoacoustic emission. Reasons for the performance discrepancy are discussed.