Final answer:
Monkeys are used instead of humans in studies involving environmental noise because of ethical considerations and their comparable cognitive abilities. Studies like those of the Harlows have shown that monkeys can provide insights into human behavior.
Step-by-step explanation:
It might be more scientifically expedient to use a monkey rather than a human being to study the effects of environmental noise levels on problem-solving primarily because of ethical considerations that prevent subjecting humans to extreme noise levels. Monkeys, although easier to work with in research settings, are not chosen because they are less sensitive to noise but because of ethical concerns regarding human subjects in potentially harmful experiments. Additionally, monkeys have similar cognitive abilities to humans which makes them valuable models for studying human-like problem-solving. For example, the Harlows' study on rhesus monkeys demonstrated that social comfort is often more important than food, highlighting monkeys' complex emotional needs similar to those of humans.