Awww that's nice to think of rats laughing. I am a bit dubious though!

Although I'm not sure exactly the meaning behind your ratty's whining sound, rats, as has already been said, do have quite a wide range a vocalizations. My little Phoebe often has the squeaky hiccups, and my Herbie often sounds like the clucking chicken or coffee perculator, but this is usually when he's feeling insecure when out free-ranging and wants to go home.

I believe there are two types of bruxing (the teeth grinding sound), the contented/happy brux and the stress brux. Recently when my big Noah was nearing the end of his life and I knew was in some pain, he was lying there bruxing very loudly and boggling like I'd never seen him boggle before, but he was in pain, so this I'd think could only have been a stress brux.

Interestingly, when my boys were babies I bought a bat detector; one of those devices that picks up ultrasonic sound and converts it into the range of human hearing. Baby rats are usually very ticklish, so I used to tickle them until I heard them laugh :) I watched a scientist do this to some lab rats in an online video; he was conducting an experiment into rat laughter. Rat laughter sounds nothing like human laughter; they omit a series of whoops and chirrups which go from low to high and it's at the time of being tickled. They also wiggle their bodies fast from side to side and appear to enjoy the experience!

Perhaps its a cough? The way you describe it sounds like some of the noises my rat Nixie comes out with...along with clucking like a hen and sounding like a coffee perculator!She has been this way since she was young and she's 22 months now.
At first I was alarmed and was watching like a hawk for signs of respiratory infection but she has never been ill and is bright and full of energy.

I have come to the conclusion that she has allergies so I am careful with scents around her and I stopped using Carefresh bedding as it was too dusty and made her worse.

Certainly the exploding firework in the distance sounds like a rat cough or sneeze so I hope this helps you!
Sarah

[quote=Sarah]
Squeaky Hiccups,with jerking of the diapraghm under the rib cage = great happiness,so much so that it makes the rat feel emotional.[/quote]

I'm glad someone else has confirmed this ! Many a time, I've been sitting at the computer (the rat cage is just behind me to the left), and I've turned round to look at them and my other rat is sitting in the hammock, gazing at me and squeakily hiccupping !
Bless him.

This odd noise also sounds like a very distant firework (the ones that make a whiny noise and then explode (but without the explosion noise, obviously)). I'm familiar with all the other noises you mention, so it's none of those.

Is it like a hiccuping squeak? I am fascinated by rat vocalizations but can find little info on the topic.One rat site I found said rats are just prone to hiccups,and if you startle them it will stop,which I totally disagree with!This (right or wrong!)is my interpretation on it:

Bruxing = contentment

Fooffing(the sudden whooshy expelling of air in a squeaky sneeze)= happy excitement

Squeaky Hiccups,with jerking of the diapraghm under the rib cage = great happiness,so much so that it makes the rat feel emotional.

So,yes,I believe the rat is crying...with joy!Scientists have proven with equipment that make the ultra sonic audible that rats giggle when playing or being tickled so its not so hard to believe!I have come to this conclusion because I have noticed my rats only make this sound when they are very bonded to me and I am cuddling and stroking them.They also hiccup when they are relaxed in their hammock and a cagemate is gently grooming them for a long time.