Omnidirectional Microphone

Because it has no rejection to aim, an omni does not change tone when the speaker turns their head, which is exactly what you want on a lapel where the mouth is off to one side. The trade is that it hears the room as readily as the voice, so it needs to sit close to the source and works badly in an echoey or noisy space. Compare it with cardioid, which rejects sound from behind and suits a fixed position in front of a speaker. Omnis also tend to handle wind and handling noise more gracefully at the same price.