Final answer:
Audio aids are best used when a sound cannot be adequately described; they should not replace a speech, should not dominate the speaker's time, and can in fact serve as both attention catchers and clinchers in a presentation.
Step-by-step explanation:
The true statement about audio aids is b. They can be used when a sound cannot be described. Audio aids serve as important tools in presentations and speeches, providing support to the speaker’s message where verbal explanations may not suffice. For example, the sounds related to medical conditions or the environment that are difficult to articulate can be effectively conveyed through audio clips.
Audio aids should complement a speech and not dominate it; they should never entirely substitute for a speaker’s narrative but rather enhance the delivery of complex or nuanced information. Furthermore, while audio aids can serve as attention catchers, they can also be used as clinchers if the sound cements the final point or message in the audience’s mind.
Therefore, options a, c, and d are not true as audio aids should not solely replace a speech, should not take up excessive speaking time, and can indeed be used effectively as clinchers.
It is clear that audio visual aids are important tools for teaching learning process. It helps the teacher to present the lesson effectively and students learn and retain the concepts better and for longer duration. Use of audio visual aids improves student's critical and analytical thinking.