(a) Concept of delay-add where the waveform from the left and the right push are repeated with the rate of fυ=1/Tυ. Δt is the time shift of the one side firing relative to the other side firing. (b) A slice image of motion with fυ=250Hz, Δt=0ms. (c) A slice image of motion with fv=250Hz, Δt=2ms. (d) Displacements at the depth of 25mm, 9mm from the left edge with fυ=250Hz, Δt=0ms for the left push, the right push, and the sum of the left and the right, respectively. (e) Displacements at the depth of 25mm, 9mm from the left edge with fυ=250Hz, Δt=2ms for the left push, the right push, and the sum of the left and the right respectively. (f) Derived interference pattern from variance as a function of the slow time at the depth of 25mm, and 9mm from the left edge.