Absorption coefficients are currently indirectly obtained from reverberation time measurements, involving impulsive or transient sound phenomena. The here‐proposed method, based on steady sound conditions, is complementary to the current one and allows one to obtain the full frequency spectrum of absorption coefficients from intensity measurements. The method is based on a model of room acoustics in terms of a linear‐feedbacked system. Following the system theory approach, the room‐average absorption coefficient is readily recognized as 1 − H, where H is the feedback transfer function. As intensity measurements provide experimental evaluation of the room transfer function, which is simply related to the feedback transfer function; absorption coefficients are consequently determined.