If the density of a medium is 1000 kg/m3 and the propagation speed is 1540 m/s, the impedance is rayls.
You are apparently talking about something called "acoustic impedance". It is the product of those two numbers.
1 rayleigh = 1 kg/(m^2 s)
To find the impedance of a medium, you need to use the equation:
Impedance (Z) = Density (ρ) * Propagation Speed (v)
Given that the density of the medium is 1000 kg/m^3 and the propagation speed is 1540 m/s, you can calculate the impedance as follows:
Z = 1000 kg/m^3 * 1540 m/s
Z = 1,540,000 kg/(m^2 * s)
Thus, the impedance of the medium is 1,540,000 Rayls (kg/(m^2 * s)).