Balanced homodyne detection is used to measure the quadrature amplitude and quadrature phase noise spectra of the probe field in electromagnetically induced transparency (EIT) medium. Through adjusting the voltage of the piezoelectric ceramic transducer, the optical path of the local light is changed so that the relative phase of the local light and the probe light in the balanced homodyne detection is adjusted. Then the noise components of the probe light with different phases are measured. It is observed that the coupling of the probe light and the coupling light leads to the increase of the noise of the probe light in eletromagnetically induced transparency medium. It is found that the induced extra noises of different quadrature components of the probe field are different for different detuning values of the coupling light. Simultaneously, the relationship between the noise of the probe field, the power of the coupling light and analysis frequency is obtained.