Abstract: As a basic psychoacoustic parameter,roughness is used to evaluate amplitude variations.According to filter characters of basilar membrane,roughness model is proposed based on equivalent rectangular bandwidth(ERB).By setting 75 filter channels on the ERB-scale,generalized modulation depth is calculated,weighted,filtered and summed to get the overall roughness.Numerical calculation results verify the validity of the model for calculating amplitude modulation signal's roughness.The proposed model also behaves better coherence to jury test data while being used for non amplitude modulation signals such as frequency modulation signal and unmodulated signals.Especially for unmodulated signals,the model ensures a correct calculated roughness in accordance with the subjectively sensed low roughness.