Electrostatic discharge (esd) mitigation for in-ear audio output devices

An in-ear audio output device, comprising:

• an earbud housing;
• a nozzle coupled to an external surface of the earbud housing and configured to extend towards an ear canal of an ear of a wearer of the in-ear audio output device and comprising a planar, distal end having one or more apertures to conduct sound waves to the ear canal of the wearer;
• a substrate positioned within the earbud housing and the nozzle, the substrate comprising:
• a first portion;
• a second portion comprising a first edge of the substrate proximate the one or more apertures;
• a metal layer on a top surface of the second portion extending, at least, to the first edge of the substrate;
• and
• a first coverlay on a top surface of a portion of the metal layer of the substrate, the first coverlay comprising a second edge proximate the one or more apertures, wherein the second edge is a greater distance away from the one or more apertures than the first edge;
• and
• a microphone surrounded by a metal casting attached to a bottom surface of the substrate, the metal casing comprising a third edge proximate the one or more apertures, wherein the third edge is a greater distance from the one or more apertures than the first edge.