"Shall I stay?"
This is the start of the second verse, in the song "Can't Help Falling in Love".
"Shall" is sung with a deep-sounding voice. Presley opens up the space in his throat, lowering the first formant. You might ask why males have an Adam's apple. Apparently, it has nothing to do with breathing, it exists so that males can have a deep sounding voice. (In my published research, I found that when a voice is rated as threatening, it has a low first formant.)
So, the first note, "shall", is strong and masculine.
The second note, "I", is the exact opposite. There is no nasality, but Presley made this note with a small space in his throat. (There is also a little bit of breathiness, and I hear no glide, making a pure note.)
Okay, we could call this femininity, but Presley has just established his masculinity. So, at least in this context, I suspect it portrays sensitivity and vulnerability.
Of course, the contrast between these two magnifies the effect. The emotion fit the words of the music. This is a song about a man who cannot help falling in love, whose heart is being taken. So Presley's interpretation contributes to the mood of the lyrics.
If the phrase is sung will all deep voice, it might sound predatory. If it is sung with all shallow voice, it sounds indecisive. I think a normal voice for the phrase avoids these interpretations, but Presley's interpretation sounds a thousand times better.
The third note reverts to normal voice -- neither large throat nor small throat, but just normal throat.
Presley usually uses the same interpretation every time a verse or chorus is song. But this effect is muted the other times he sings these notes. The effect wouldn't make much sense for "Wise men say", which are the words the first time these notes are sung. It would fit "Take my hand", but perhaps Presley doesn't want to emphasize the word "my".
This is one Presley technique I can imitate to full effect.