On 18:39 15 Mar 2021, Bert Coules said:

I've uploaded a 28 second WAV file with a sample recording from
all three microphones currently available to me: the Logitech
webcam, the separate cheapo desktop mic, and the mic in my old
(low grade video) webcam.

In each instance I was speaking at the same level and at roughly
the same distance. Recording made in Audacity with the mic input
control at maximum (and the recorded level startlingly low). I've
done nothing to clean up or alter the recordings, since what I'm
after is a decent sound quality for live Zoom chatting.

If anyone would be kind enough to listen I'd be grateful for any
thoughts.

http://bertcoules.co.uk/non%20websit.../Audio/Mics%20
test%2015th%20March%202021.wav

Using your WAV file, the levels of the Logitech (first) and desktop
(second) are quite different. See this chart.

https://ibb.co/TwM8mbq

The frequency responses are also different. See the charts (the
scales are slightly different in each case). I don't know if your
ears can hear it but you can see the horrible HF interference on the
desktop mic and I wouldn't use it.

https://ibb.co/K2qGjM8

For completeness, this is your other webcam.

https://ibb.co/x599KtH

Charts won't tell exactly how a mic will sound but they're a
starting point. Intelligibility on video calls does not necessarily
follow better specification.

Your webcam provides a digital signal to the PC, while the desktop
electret provides an analogue one. Controls for each (level, EQ,
etc) within the PC will be different.

The Logitech sounds better to me but perhaps you find it too smooth.
Maybe Windows 7 lets you attenuate the bass frequencies or apply a
bass-cut (high pass) filter.