After a lot of experiences, we came up with a few guidelines on audio:
Script! Unless you are a natural breath taking speaker, put everything you want to say on paper;
Audio and text should complement each other. Do not allow audio to interfere with reading from the text and vice versa, otherwise it is like watching a karaoke.
What to think of when you speak:
• be natural and keep breathing;
• use the complete scale of your voice to avoid monotony. Use high and low tones, emphasize important words (you can highlight them in the script/text you are reading)
• Visualize what you are saying; it makes you sound more interesting.
• Use style, vocabulary and tone appropriate to the learner’s target population.
• Use short sentences.
• Read the script out loud and listen to how it sounds, edit the parts that do not sound right.
• Keep your language simple, use the active voice, and be direct. Direct I tell you!
• define all unfamiliar terms or words or provide a syllabus in which the learner can find it.
• make logical transitions. And to be sure they are logical: ask colleagues.
• Provide a corresponding visual for every piece of narration.
• keep your audio short and to the point. Avoid extended narration.
• If you are speaking to an international audience, you might consider speakers with a different English dialect. It is more compelling to the students from those regions as well. Of course, it needs to stay clearly pronounced.
• keep the human/humour in. If you misspeak something, rectify it in a natural voice (“Aaah, that was wrong, let me rephrase this part…”) the fact that you make a mistake, gets the learner’s attention as well.
KISS, keep the audio script short and simple. Break it into little parts whenever it is relevant and possible. Insert instructional activities to keep the students active and motivated
If you know any other guidelines, please let me know.