Interferences? phase shift $$\Delta \phi$$ is to $$2\pi$$ what time shift $$\Delta \tau$$ is to time period $$T$$ Hence $$\Delta \tau=\Delta \phi\times T/2\pi=\Delta \phi /2\pi\nu$$ You can see that for a given $$\Delta \phi$$ , $$\Delta \tau$$ is inversely proportional to frequency $$\nu$$.