Voice quality from worst to best:
1. cell phone
2. wired phone
3. Skype
4. in person
My hearing has declined somewhat (too much fooling about with hotrods), making the situation worse.
Another thing I've noticed when listening to a talk show. It's easier to understand the host than the guest, especially when the audio is speeded up. Apparently, a professional host enunciates words better.
I've looked around for a speech coach to improve my enunciation for the presentations I give, but all I could find were autism speech therapists and singing coaches, sigh. (I want to improve my enunciation because the easier it is for people to understand my speech, the more they'll pay attention to my presentation. I know that I sometimes give up listening to a presentation when I have to work too hard to understand the speech.)
I've been doing a lot of video conferencing for work these days (like everyone else) and decided to trash my $5 mike and get a semi pro one so people could hear me clearly.