[kevin_b_er]

The 's' is voiced in the verb and voiceless in the noun, at least in my midland accent, which is probably closer to American TV's accents. By 'voiced', I mean your vocal chords vibrate and make a sound for it. But the lip/teeth/tongue are the same.* There are several noun/verb words where the pronunciation changes and lots where the stress changes. Another pronunciation change example that I can think of right now is 'close': The noun and the verb do the same thing with final sound.

The voiced 's' is a 'z' sound. And English sadly doesn't use a different letter here.

*In simple terms. I think these form an identical mouth shape, but there's probably a dialect where it doesn't. And some bizarre cases where it doesn't. Because English. And judging from another comment from someone from Michigan, they say both the same?? Also 'housing' for me uses a voiced s, but I think I've heard 'housing' both ways.