They forgive the picture, not the sound

People will keep watching a video shot in poor light. They will not sit through hiss, room echo or a voice coming from far away — they leave in the first second. Yet most people worry about lighting first.

Distance beats microphones

A phone microphone is good at a hand's width and bad at two metres. Before buying a lavalier, move the phone closer; if you have wired earphones, even their microphone beats holding the phone at arm's length. If your framing needs distance, treat the microphone as a separate problem.

The room decides the echo

Empty rooms with hard surfaces echo: the sound bounces off the wall and enters the microphone a second time. Curtains, a rug, a bookshelf — even a bedroom — absorb that return. The same sentence on the same phone sounds completely different in two rooms, and testing it takes a minute.

• Turn off the air conditioning, the fan and move away from the fridge: the hum you miss while recording is obvious in headphones.
• Close the window; traffic sits right on top of speech.
• If you hold the phone, keep your finger off the microphone on the bottom edge.
• After recording, listen to the first five seconds on headphones. If the problem is there, record again — editing will not fix it.

Viewers put up with a bad picture; they mute bad sound.