Audio aids are instructional materials that can only be heard and not seen. They provide images of concepts, people, and situations to students. Some key advantages of audio aids include saving time, reducing the teacher's burden, motivating students, and facilitating different learning styles. Examples include radios, tape recorders, and language labs. While audio aids increase interest and comprehension, disadvantages include potential boredom if overused, reliance on properly-functioning equipment, and inability to use in all locations. Effective use of audio aids involves planning, preparation, and discussion to maximize their educational benefits.