Is this in the ground or a pot? We think it is mostly from drought and heat stress. Are you watering and fertilizing on a regular schedule? If you cut off the damaged leaves and make sure to water and fertilize with a liquid fertilizer that should help send out some new healthy leaves. 

It looks like it could potentially have some small stippling damage from spider mites as well. See if you can find any along the leaves or any small webbing. You can do a paper test for them by holding a white piece of paper under the leaf and tapping the leaf to see if you see any small black specks on the paper. These are a very common pest for banana plants and especially when the temperatures are high. The link provided will describe some management tips. Hosing off the leaves with a strong stream of water is a good start. Do so in the morning so the water can dry off slowly as the temperatures rise.

Let us know if you have additional questions. 

Emily