Sound transmission and reflection properties of a lossless fluid layer imbedded in another fluid are analyzed in terms of a resonance formalism similar to one that has been used in nuclear scattering theory, and more recently in acoustic scattering theory. Expressions for the transmission and reflection coefficients have been obtained which manifestly exhibit the resonance character of these functions. The formalism provides an explicit determination of the position, width, and strength of each individual resonance contribution, and links these resonance quantities to the material constants of the layer and its surroundings, thus indicating a novel way to determine these constants by a measurement of the acoustic transmission and/or reflection coefficients. Within the limits of the resonance approximation, the resonance positions may be obtained by solving a purely real characteristic equation, which constitutes a distinct computational advantage over the solution of the complex eigenvalue equation thought to be necessary for a loaded layer.