Sound

To voice record you could use a specialised voice recorder such as a zoom H4N , a mobile smartphone - using a voice memo app or the camera app and select video or a specialised camera. 

When recording you need to take may things into consideration, things such as the amount of time your recording, whether batteries are in  the device ( if you are using a camera or recorder ) or the amount of battery your smartphone has, the location , if your outdoors , is it windy ? is it dry ? is it raining ? , if your indoors , are you in a quiet room, does it contain sound panels or not ? , the amount of people you are with , and most importantly you have an SD card with enough storage or your phone is backed up and has enough storage.