External iSight microphone audio not working I'm using a 2003-era external iSight &quot;Autofocus Video Camera + Noise Suppression Microphone&quot; with an Apple Cinema Display and USB-C MacBook Pro running macOS 10.15.
It's connected via a long succession of dongles:

iSight &gt; FireWire 400 &gt; Apple Cinema Display &gt; FireWire 800 &gt; Thunderbolt 2 &gt; Thunderbolt 3

It still works great for video, if a bit low resolution, and you can't beat the design:

However, the iSight camera's microphone does not appear to be working. People cannot hear me when my laptop is in clamshell mode, despite being on video via the external iSight.
In System Preferences &gt; Sound &gt; Input I only see &quot;MacBook Pro Microphone&quot;:

System Information shows a FireWire iSight device, as well as an &quot;Unknown Device&quot;. When I unplug the FireWire cable/dongle, both devices disappear.

This iSight is running the 1.0.2 firmware; I'll try to update it with 1.0.3 and test:

How to update external iSight firmware?

Why isn't the iSight mic working? How can I use an external iSight as an audio/video webcam in modern versions of macOS?

Related threads that seem to be experiencing the same issue:

https://discussions.apple.com/thread/250914849
https://discussions.apple.com/thread/251255964
https://discussions.apple.com/thread/251293054
https://discussions.apple.com/thread/252233406
The FireWire iSight audio driver has been omitted from recent macOS releases.
A Mac Rumors contributor has posted a download of the driver from his backup.
Download iSightAudio.driver there, or find the same driver from your own backup.
Place the file in /Library/Audio/Plug-Ins/HAL/
In case there were any other inconsistencies from the original I used a copy from a backup of OS X 10.13. A Finder copy and authentication worked without any permissions issues.
This worked for me on Catalina 10.15.6 on a 4,1-&gt;5,1 cMP.