The untiy Resources directory dynamically loads resources

First of all, the folder must be called Resources, and the name cannot be wrong.
All resources in Resources will be loaded when the program starts. If the content is too large, it will have a greater impact on the startup time.Care not to recommend using
but in practice we often use

This is an example of loading an audio clip

 AudioClip ac = Resources.Load<AudioClip>("Voice/"+ voiceName);

There are two points to pay attention to
1. You do not need to write / before the secondary folder of Resources, and you need to write a / before the streamingAssets folder.
2. The Resources file only needs to give the file name, no suffix name is allowed