Mr Gresham stepped down from his work last year due to ill health.
However we can listen to his voice in a number of recordings. Best known of these are his introductions on the Focus on the Family Narnia series.
He has also done other audio recordings, and today I found these links, which might interest some people.
https://www.audible.com/search?searchNarrator=Douglas+Gresham
https://soundcloud.com/harpercollinspublishers/the-abolition-of-man-by-c-s-1
https://www.harperlibrarybookclub.com/9780063136687/c-s-lewis-essential-audio-library/
You can also find a number of talks on YouTube.
You may like to post a link in a reply, if you find other sites, or a Youtube talk you liked.
There, shining in the sunrise, larger than they had seen him before, shaking his mane (for it had apparently grown again) stood Aslan himself.
"...when a willing victim who had committed no treachery was killed in a traitor's stead, the Table would crack and Death itself would start working backwards."