"Whistling" speech impediment (like Gopher from "Winnie the Pooh")?

Factual Questions
1

I was watching a classic of western cinema the other night* that featured a character with an odd speech impediment—every time she spoke an “s” sound, she pronounced it as a whistle.

It occured to me that I’ve heard this before, on TV at least. Most notably by “Gopher” from the Winnie the Pooh cartoons (couldn’t find a clip online—this fella on Youtube does a fairly good rendition), and I think a few grizzled 1840s prospectors in old westerns.

My question is: what’s the name of this particular speech impediment, if it has one? And (assuming it actually exists in the real world—I’ve never heard it in real life), what would typically cause it?
*Okay, it was the first “Care Bears” movie. Hey, I hadn’t seen it in 20 years! When I was a little kid! Who are you to judge me!?

2

As I understand, it’s typical when teeth are missing. For reference, listen to Spike Jones’ rendition of “All I Want For Christmas is My Two Front Teeth.”

3

rick williams a local news anchor in phila., pa does this and seemingly has teeth.

seems more a tongue postition thing.

4

A gap between front teeth can do it.

5

There was a guy on a gardening show here in Australia about 20 years ago who used to do this. Cruelly, his name was Alan Seale. Everyone used to look forward to Alan Sssssseale ussssing hisssss sssecateursss on the thissstlesss to sssstop sssap sssucking insssectsss.

6

Ah, memories. As children we used to lampoon poor Mr Seale mercilessly.

7

I can hear some s-emphasis in this YouTube vid of Allan Seale plugging gardening cards – not really that noticeable, though.

8

It is called a “sibilant s”.

A rather hysterical episode of News Radio dealt with this issue a few years ago.

9

Apparently Dan Rather is believed to have this issue.

http://thatvideosite.com/video/115

10

Here’s a thread where I asked the same thing.

11

The guy who did the voice for Gopher on “Winnie The Pooh” was Howard Morris. He did voices for dozens of cartoons. I recall seeing him on “The Show Of Shows”. Wasn’t that whistling speech his schtick? Did he talk like that in real life?

12

No sign of a sibilant s that I can hear in this clip with Morris as Dr. Sivana. Must have been just his schtick for the part.