Growth‐of‐masking functions were obtained from 19 normal and 5 hearing‐impaired listeners using a simultaneous‐masking paradigm. When masker and probe frequency are identical, the slope of masking approximates 1.0 for both normal‐hearing and impaired listeners. For masker frequencies less than or greater than probe frequency, the slopes for impaired listeners are shallower than those of normals. These findings are consistent with previously reported physiological data (single‐fiber rate versus level and AP masking functions) for animals with induced cochlear lesions. Results are discussed in terms of a potential masking technique to estimate the growth of response in normal and impaired ears.