Example of fine-tuning the audio sub-network.

I want to perform the fine-tuning of the audio subnetwork to fit my audio classification problem.
To this aim, I plan to use the `_construct_linear_audio_network`, `_construct_mel128_audio_network`, and `_construct_mel256_audio_network` functions to load the pre-trained Keras model and then append one or more fully-connected layers to perform the classification.

However, I don't understand the Input shape of such models. According to the `models.py`, the input shape is `input_shape = (1, asr * audio_window_dur)`, where `asr= 48000` and `audio_window_dur=1`; what's `asr` and why it has that value? Can you please provide an example of using the Keras model from the `.wav` file?

I really appreciate any help you can provide.

Start in models.py with _construct_linear_audio_network, _construct_mel128_audio_network, and _construct_mel256_audio_network to clarify the input shape and the meaning of asr. Done means documenting how to use a pre-trained Keras audio model with a .wav file and append fully connected layers for classification.

Written by the indexing model from the issue text.