Time Domain Computation of a Nonlinear Nonlocal Cochlear Model with Applications to Multitone Interaction in Hearing

A nonlinear nonlocal cochlear model of the transmission line type is studied in order to capture the multitone interactions and resulting tonal suppression effects. The model can serve as a module for voice signal processing, it is a one dimensional (in space) damped dispersive nonlinear PDE based on mechanics and phenomenology of hearing. It describes the motion of basilar membrane (BM) in the cochlea driven by input pressure waves. Both elastic damping and selective longitudinal fluid damping are present. The former is nonlinear and nonlocal in BM displacement, and plays a key role in capturing tonal interactions. The latter is active only near the exit boundary (helicotrema), and is built in to damp out the remaining long waves. The initial boundary value problem is numerically solved with a semi-implicit second order finite difference method. Solutions reach a multi-frequency quasi-steady state. Numerical results are shown on two tone suppression from both high-frequency and low-frequency sides, consistent with known behavior of two tone suppression. Suppression effects among three tones are demonstrated by showing how the response magnitudes of the fixed two tones are reduced as we vary the third tone in frequency and amplitude. We observe qualitative agreement of our model solutions with existing cat auditory neural data. The model is thus simple and efficient as a processing tool for voice signals.Comment: 23 pages,7 figures; added reference

Nonparametric identification of a binary random factor in cross section data

Suppose V and U are two independent mean zero random variables, where V has an asymmetric distribution with two mass points and U has a symmetric distribution. We show that the distributions of V and U are nonparametrically identified just from observing the sum V +U, and provide a rate root n estimator. We apply these results to the world income distribution to measure the extent of convergence over time, where the values V can take on correspond to country types, i.e., wealthy versus poor countries. We also extend our results to include covariates X, showing that we can nonparametrically identify and estimate cross section regression models of the form Y = g(X;D*)+U, where D* is an unobserved binary regressor.

WORKPLACE HAPPINESS IN EXPRESS INTERNATIONAL SHIPPING SERVICE PROVIDER

The purposes of this research were 1) to study the level of workplace happiness in express international shipping service provider and 2) to study the factors affecting workplace happiness in express international shipping service provider. The sample was 385 employees in express international shipping service provider in Bangkok. Convenient sampling method was used to collect data. The questionnaire was used as research instrument. Statistics used for data analysis included percentages, mean, and standard deviation. Multiple Linear Regression Analysis was used for hypothesis testing. The research findings were: 1) The workplace happiness in express international service provider was at high level. 2) Employment condition, communication, working relationship, job characteristics, and organizational culture could affect workplace happiness in express international service provider at statistical significance level of .01. Compensation could affect workplace happiness at statistical significance level of .05. All independent variables could explain the variation in workplace happiness in express international service provider at 72.1