Answer:
Signal Detection Theory.
Explanation:
Signal Detection theory is the ability that helps in differentiating between the patterns that give information and patterns that distract us. The theory is used in many areas such as telecommunications, psychology, etc.
In the given case, Catherine was able to recognize the voice of her son because of the signal detection theory. She was able to eliminate the patterns of voice coming from the cheering of crowds and able to detect the voice of her son.
So, the correct answer is the signal detection theory.