primary micriPhone should be repaired. what is its name to buy online?

my lumia 1020's primary micriphone (through which i could attend call) isn't working. secondary microphone is working properl...like if i attend call at loudspeaker, cortana, video and audio recording are working normally. but I'm unable to get repaired by nokia/Microsoft care as they refused because they don't have the "parts". so i need to repair it myself. i bought tools to do that. and i can do that too (i replaced the battery and USB port myself). but I don't know the name of the 'part' that is primary microphone. searched in ebay and Amazo, tried to contact the sellers but they didn't respond yet. please suggest me.