Construct a Punnet square. Cross KM, Km, kM, km with Km, Km, km, km (these are all the possibilities). The offspring will thus have: KKMm, KKMm, KkMm, KkMm, KKmm, KKmm, Kkmm, Kkmm, kKMm, kKMm, kkMm, kkMm, kKmm, kKmm, kkmm, kkmm.
Now, anybody without K or with M will be deaf. They are bolded below:
I think the 16-size Punnet square is the best and most straight-forward way of doing it but whatever seems easiest for you. I didn't have to go fill everything in. I simply crossed out all rows and columns that had a big M and looked to see which crosses would end up with two small k's. The only time-consuming part was writing out the four possible combinations for each parent.
I usually just do this, because its faster and I'm lazy af.
You know that in the presence of one big M no matter what other alleles look like, that child will be deaf, so you check columns 1 and 3.
You also know in presence of big A, people will hear fine, so aa means deaf, check all the options where aa appears.. (I used A here, because K and k look identical on paper.)