Yes, I do. It's a known issue that some Lumia 930s/Icon have a design issue that causes two of the four microphones to become defective in time. Weird thing is, that if you blow air into the speaker microphone, it actually senses that sound, but otherwise it won't work, and all apps that don't use the bottom microphones will not work properly. For example, Voice Recorder doesn't work, WhatsApp voice messages come with no sound (like you said), and for some people, recording vertical video makes the app use the defective microphones.