A Digital Waveguide Section

Both plane waves of a cylinder and spherical waves of a cone can be modeled using a digital waveguide.
For an infinitely long tube, filter $\lambda (\omega )$ accounts for the one-way propagation loss.

Figure 1: A waveguide section for an acoustic tube showing delay and wall loss $\lambda (\omega )$ .
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For a cone, an addtional filter is required to account for spherical spreading at a distance $\rho$ from the cone apex:

Figure 2: A waveguide section for a cone showing the additional spherical spreading $\rho$ .
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**Figure 1:** A waveguide section for an acoustic tube showing delay and wall loss $\lambda (\omega )$ .
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**Figure 2:** A waveguide section for a cone showing the additional spherical spreading $\rho$ .
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