Amazon.com: Digital Camera External Microphone Compatible with Nikon D3400 DSLR Digital Camera, XM-AD2 Dual Channel XLR-Mini Audio Adapter for DSLR's, Camcorders and Pro Video Cameras : Electronics
VidPro BF458086 Nikon D3400 Digital Camera External Microphone Vidpro XM-L Lavalier Microphone
Nikon D3400 DSLR Digital Camera External Microphone Vidpro XM-55 Microphone Kit | eBay
Nikon D3400 microphone settings | How to record good sound with your Nikon # D3400 - Youtube - YouTube
Nikon D3400 Camera External Microphone | Microphone Audio Jack | Microphone Adapter - YouTube