So many times in my professional development training sessions, I have referenced adding your voice to your power points that are posted online, especially when posting to your Moodle courses. But for those without Moodle courses, you might post your power point presentations to your classroom website page or even a Google Drive account so you can share it with students, like those who were absent or who might need to hear it a second time.
Have you tried using the “narration” button that is located on the same menu as the slide show button (top of the screen in power point)? It allows you to record your voice while presenting each slide separately or several slides all together – for those brave enough to do more than one slide. Check out this blog post from Emerging Ed. Tech – they have a great description of this narration tool: Add Voice Overs to Power Points in 5 Easy Steps.