Hz A A A A A A LDL for speech Aided Speech output Functional Gain: The way hearing aid gain was 1st verified Figure 1

* dB SPL at TM 120 Frequency * * * * * * dB Gain REAR REUR Target REIG Then Came Insertion Gain: Aided vs Unaided SPL at the TM Figure 2

* dB SPL at TM 120 Frequency * * * * * * * * * ** * * Today we use Insitu Output: Map Soft, Average, Loud speech into remaining Dynamic Range LDL * * * Normal HL * * * Targets: Loud Average Soft Figure 3