Instead of closing the Slide Audio dialog box between every recording, you can record to multiple slides in one session.
Before you start, make sure you have typed or pasted the voiceover script for each slide into the Slide Notes pane.
To start the multiple slide recording process, choose Audio > Record to > Slides (notice the plural word slides).
The Record from Slide dialog box opens. Choose the range of slides you want to record and click the OK button.
The Slides Audio dialog box opens. Notice that on the waveform area, a marker for each slide has already been set.
To display your slides as you record, select the Preview check-box below the audio waveform. Use the blue arrows to navigate to the first slide you want to record to. (When you are on the first slide, the Previous slide arrow is grayed out.)
To display your slide notes, which contain your voiceover script, click the Captions & Slide Notes button at the bottom left of the Slides Audio dialog box.
Your slide notes for the active slide are displayed. Use the A tool at the upper right to adjust the font size for ease of reading.
After calibrating your microphone (refer to my Calibration article to learn how), ensure that the Continuous Play check-box is NOT selected.
Click the Record button to start recording. After the countdown, record your narration by reading it from the Captions & Slide Notes window. When you finish the narration for your first slide, click the Stop Recording button.
To advance to the next slide, click the Advance Slide blue arrow below the waveform area.
The slide advances. The Captions & Slide Notes display window disappears, presumably to allow you to see the Preview of the next slide. Once you click the Record button, the Captions & Slide Notes window reopens automatically, displaying the notes for the next slide.
Click the Record button and record the next slide, then click Stop recording.
Continue in this way through all of your slides. The timing for each slide is automatically extended to accommodate the amount of time your narration requires.
After you have recorded the narration for the final slide, click the Save button at the lower right of the Slides Audio dialog box.
On the Filmstrip, each slide you recorded to now shows a speaker icon, indicating that your slide audio has been saved.
Once the narration has been recorded, you can preview the audio for each slide by clicking that speaker icon and choosing Play.