My brother can't burp?

Its very odd.
He NEVER burps. He says it comes up to about the mid chest and he tries to force it out, but it just doesnt. However he does make this strange noise that i really cannot describe via text (but hopefully you might know what im talking about if you have heard of this??) and he says that it relieves pressure in his chest. Please explain if you know what in the world im talking about here...