Voice quality
It is, of course, important that your audience be able to hear you clearly throughout your presentation. Remember that if you turn away from your audience, for example towards the whiteboard, you need to speak a little more loudly. In general, you should try to vary your voice. Your voice will then be more interesting for your audience. You can vary your voice in at least three ways:speed: you can speak at normal speed, you can speak faster, you can speak more slowly - and you can stop completely! You can pause. This is a very good technique for gaining your audience's attention.
intonation: you can change the pitch of your voice. You can speak in a high tone. You can speak in a low tone.
volume: you can speak at normal volume, you can speak loudly and you can speak quietly. Lowering your voice and speaking quietly can again attract your audience's interest.
The important point is not to speak in the same, flat, monotonous voice throughout your presentation - this is the voice that hypnotists use to put their patients' into trance!
Visual aids