Non-Linearities in Masking Patterns of Pure Tones

Masked thresholds of test-tones at frequencies f _T are determined as a function of the SPL L _M of a pure tone masker at frequencies f _M. In the case of f _T > f _M the test-tone amplitude increases more than proportional relative to the masker amplitude in a limited range of 40 dB sensation level (rise factor ΔL _T/ΔL _M = 2.5). An increase less than proportional is observed in the case of f _T < f _M (0.3 < ΔL _T/ΔL _M < 0.8). The important parameter proves to be the critical band difference Δz = z _T – z _M, almost independent of the absolute frequency range. The results are rearranged and discussed in terms of masking patterns, paying regard to the distinct interindividual differences in the case of f _T > f _M.