text: Are you talking about words that sound like they have a "z" sound where it is spelled with the letter "s"?\n\n"s" becomes "voiced" when it appears between voiced sounds. "s" and "z" are exactly identical, except for one thing: "s" is unvoiced and "z" is voiced. The same is true for "p" & "b," "k" & "g," "t" & "d," "f" & "v," "ch" & "j," "sh" and the s-sound in "measure," and the two "th" sounds.\n\nWhat's a voiced sound? Put your hand on your throat when you speak. Your vocal cords vibrate when you make a voiced sound. In English, the voiced sounds are a,b,d,e,g,i,j,l,m,n,o,r,u,v, w,y,z, th as in "then," and x as in xylophone. The unvoiced sounds are c,f,h,k,p,q,s,t, th as in "thin," ch, sh, and x as in box.\n\nAlso, the voiced counterpart of "sh" is often spelled with an "s," as in "measure," "usual," and "casual." It's sometimes spelled with a "z" like "azure" or "g" like "garage."\n\nAnyway, not all sounds sound the same all the time. For example, let's look at how "n" changes. Say "nose," and pay attention to where your tongue is. Now say "anger" and pay attention to where your tongue is. It's different, isn't it?? For "nose," the tip of your tongue touches the ridge behind your upper teeth. For "anger," the tip of your tongue NEVER touches ANYTHING, but the back of your tongue rises to the back of your throat. That's because the "n" in "nose" and the "n" in anger are two completely different sounds! "n" turns into that second sound when it appears before a "g" sound. This is called an "allophone-" a change a sound makes when it appears next to certain other sounds.\n\nLet's look at some allophones of "t." Say "top." The tip of your tongue touches the ridge behind your teeth. Now say "button." Your tongue winds up on the ridge when you say the "n"- but notice it's not there for the "t!" The sound of the "t" in "button" is made inside your throat- inside your glottis, to be precise. Now say "beauty"- doesn't it sound more like "beaudy?" That's because "t," like "s," becomes voiced when it appears between voiced sounds.\n\nSo, when dealing with s, it sounds like "s" in words like "soda," "sleep," and "bits," but when you put it between voiced sounds, it becomes "z," such as "easy," "business," and "president."\n\n(also notice- Say "look out for the bees" sounds like and "s," But "Bees are in my hair!" sounds like a "z." Technically, phoneticians (people who know about this stuff) say that "s" becomes voiced after all voiced sounds, but then the "z" becomes de-voiced if it's not followed by a voiced sound, so things cancel out and it just sounds like "s" again. That's why I told you that the voicing only happens BETWEEN voiced sounds.)\n\nOne final note- American English has changed some of these voiced-s words to a more accurate spelling with "z," while British English retains the original spelling. For example, "organization" is the American spelling, and "organisation" is the original British spelling. Now we see here a very interesting occurence- "organisation" was originally spelled with an "s" despite the "z" sound because its ROOT WORD is "organise"- a word that very distinctly ends with a voiceless "s" ("z&quot