I'm in that club of people who saw this episode of "Suspicion" as a child back in the late 1950's. I remember it was one the kids at school talked about the next day. It made an impression.
The amazing thing is that so much is left to our imagination. It didn't have that much in the way of special effects; just a few sets really. At present, there is a blurry old copy on YouTube, and although you struggle to see anything, the story still works. Would millions of dollars' worth of CGI effects have made it any more chilling? I doubt it.
At the time we saw programs like this on TV, we also had those brilliant anthologies of short stories in paperback, a lot of them under Alfred Hitchcock's banner as well as editions of "The Pan Book of Horror Stories". Read around a campfire at night, some of those stories could make the hairs on the back of your neck stand up - our pleasures seemed simpler back then.
Later I realised that many of the stories in those collections were quite old, some from the early 1900's or even from the 1800's.
In fact, "Voice in the Night" is a faithful adaption of a short story written in 1907 by William Hope Hodgson, a fascinating man who produced dozens of stories before he was killed during WW1.
After 60 years, we aren't likely to see a better copy of "Voice in the Night", but does it matter? The real power is sometimes in what you don't see.