The eye can detect 5 x 104 photons per square metre per sec of green light λ=5000Ao while the ear can detect 10-13 W/m2. The factor by which the eye is more sensitive as a power detector than the ear is close to

E=123755000=2.475eV≈4×10−19JSo  the  minimum  intensity  to  which  the  eye  can  respondIEye=photon  flux×Energy  of  a  photon⇒IEye=5×104×4×10−19=2×10−14W/m2Now  as  lesser  the  intensity  required  by  a  detector  for  detection,  more  sensitive  it  will  beSEyeSEar=IEarIEye=10−132×10−14=5  i.e.,  as  intensity  powerdetector,the  eye  is  five  times  more  sensitive  than  ear.