An improved WKB calculation for a two-dimensional cochlear model.

The finite difference calculations of Neely [E.D. thesis, California Institute of Technology, Pasadena, CA (1977)] and the WKB solution of Steele and Taber [J. Acoust. Soc. Am. 65, 1001-1006 (1979)] generally agree, except in the "phase plateau" region, where both are irregular. In the present work, an improvement in the accuracy of the WKB procedure is gained by using a closed-form integral which gives the phase and damping functions in the short wavelength region. The present results agree qualitatively with the preceding but show a smooth variation with frequency and distance along the cochlea.