There is no logic in place to allow arbitrary objects to be accepted as inputs for neural networks. Mathematical calculations are done on the inputs, but arbitrary objects do not support mathematical calculations.
Neural Networks require numeric vectors of "features", but the underlying tools do not care whether the features are extracted from "images" or audio files or just plain "data".
Some of the interfaces such as Convolutional Neural Networks expect images because image processing is what they are optimized for.
If you have a particular interface in mind, then possibly someone could estimate the effort to change it to use a different form of input.
