From my E-M1 MkII manual:
Audio recording Audio can be added to still images (up to 30 sec. long).
1 Display the image to which you want to add audio and press the Q button. • Audio recording is not available with protected images. • Audio recording is also available in the playback menu.
2 Select [R] and press the Q button. • To exit without adding audio, select [Cancel].
3 Select [R Start] and press the Q button to begin recording.
4 Press the Q button to end recording. • Images recorded with audio are indicated by a H icon. • To delete recorded audio, select [Erase] in Step 3. 100% JPEG JPEG Edit Add to My Clips Share Order 0 R Rotate Back 100% 100% R Set Cancel R Start Erase Back