NAL Algorithm or Gain by Frequency


I have a question about programming the Tympan so that specific amounts of gain can be applied to specific frequency bands. I am looking for something either identical to or similar to what the NAL algorithm would calculate for traditional hearing aids. Is there any code/program available that would allow a user to type in the amount of gain desired at specific frequencies similar to traditional hearing aid software? We would like to use the Tympan in a project where we present ripple noise to listeners with hearing loss and we would like to route the ripple noise to the Tympan and have it compensate for any loss of audibility by adjusting the gain across frequencies for the listener’s hearing loss. Thank you for your help!

Kristi O.


The linear version of NAL-R can be easily implemented by following the equations in Byrne & Dillon (1986) [Byrne, D. and Dillon, H. (1986). The National Acoustic Laboratoriesʼ (NAL) New Procedure for Selecting the Gain and Frequency Response of a Hearing Aid. Ear and Hearing, 7(4), pp.257-265.]. The nonlinear versions, NAL-NL1 and NAL-NL2 are much more complicated and use neural network models. My understanding is that the code for these can only be used with special permission and can only be obtained directly from NAL.