Sound fields (pressure amplitude) in inhomogeneous waveguides having sound-speed profiles without ((a) and (b)) and with ((c) and (d)) a scatterer. The sound source is a point source located at y = 0.2h where h = 30 m is the depth. The frequency is f = 500 Hz. The sound-speed profiles in the host medium are assumed to be the same in both cases expressed as c = 1500 × (1 − 10⁻³y) as shown in the left panel. (a) Sound field in the waveguide with no scatterer. The result is computed by the multimodal method; (b) Sound field in the waveguide with no scatterer. The result is computed by a numerical calculating software COMSOL Multiphysics; (c) Sound field in the waveguide containing a scatterer with parameters ρ/ρ₀ = 0.3 and α = 0.5. The result is calculated by multimodal admittance method; (d) Sound field in the waveguide with the same scatterer as in panel (c). The result is calculated by COMSOL Multiphysics.