Imagine a dentist telling a small child to "open wide." He might "sing" it rather than say it, maybe by drawing out "wide" into two syllables, the first having a higher pitch than the second. You probably know what I mean. Is there a good, single verb for this? I could just write "'Open wide,' he sang", but it's not ideal.
intone - to utter in a singing voice; to utter something in singing tones or in monotone
"Open wide," he intoned.