In certain cases where behavioral thresholds cannot be attained, ABR thresholds can be used for hearing aid fittings. New fitting formulas such as DSL v5.0 allow the user to base the settings in the hearing aid on the ABR thresholds. Correction factors do exist for converting ABR thresholds to behavioral thresholds, but vary greatly. For example, one set of correction factors involves lowering ABR thresholds from 1000 to 4000 Hz by 10 dB and lowering the ABR threshold at 500 Hz by 15 to 20 dB. Previously, brainstem audiometry has been used for hearing aid selection by using normal and pathological intensity-amplitude functions to determine appropriate amplification. The principal idea of the selection and fitting of the hearing instrument was based on the assumption that amplitudes of the brainstem potentials were directly related to loudness perception. Under this assumption, the amplitudes of brainstem potentials stimulated by the hearing devices should exhibit close-to-normal values. ABR thresholds do not necessarily improve in the aided condition. ABR can be an inaccurate indicator of hearing aid benefit due to difficulty processing the appropriate amount of fidelity of the transient stimuli used to evoke a response. Bone conduction ABR thresholds can be used if other limitations are present, but thresholds are not as accurate as ABR thresholds recorded through air conduction.