Lien À Trois

It sounds like you're referring to the presence or absence of alphabet letters.

song	sounds like	as in
Noel	"no L"	There's no L in "idea," but I heard a friend say, "I have an ideal."
There Is A Sea	"There is a C"	There is a C in "victuals," but it's silent.
A Pair Of Eyes	"a pair of I's"	The word "skiing" has a pair of I's in it. That's very rare!