## Abstract

This report presents the WKB approximation for the curvilinear horn (CH) equation, numerical comparisons of horn theories, and a model of viscothermal effects for acoustic wave propagation in axisymmetrical horns. The WKB solution is presented for the hyperbolic horn. The numerical comparisons for a hyperbolic horn profile show that the CH equations are more accurate than the plane-wave horn equation or previous spherical-wave horn equations. The CH equation using spherical coordinates has only small errors compared to the CH equation using oblate spheroidal coordinates. A variational derivation of viscothermal losses is constructed based upon the concept of wall admittance using orthogonal coordinates. The important case of the spherical-wave horn equation is considered as a special case using the first-order WKB theory. Differences from existing theory are observed near the apex of the cone.

Original language | English (US) |
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Pages (from-to) | 285-XI |

Journal | Acustica |

Volume | 85 |

Issue number | 2 |

State | Published - 1999 |

## ASJC Scopus subject areas

- Acoustics and Ultrasonics