This is a deliberately simplified 2D model, not the 3D under-ice scene flattened: everything moves in one plane, ice floes are plain circles, and the narwhal's click train is drawn directly on screen as a fan of rays whose brightness is the actual computed echo strength — dim rays are directions the return click is too weak to hear over the ambient noise floor. The ranging math is the same real physics as a click-train biosonar:
d = c·Δt/2 (time-of-flight, one click)
θ_beam ∝ asin(1.22·λ/D) (melon aperture narrows at higher f)
c = 1450 m/s (speed of sound in cold seawater); λ = c/f is the click wavelength and D is the fixed effective aperture of the narwhal's melon, so raising the click frequency narrows the beam (sharper bearing on prey) but the return also loses more energy to absorption over range — the same frequency/range trade-off a real narwhal makes when it clicks faster and higher-pitched closing in on prey under the ice.