Okay, I have been trying to find the word for this vocal trick/note trick for so freaking long. I don't even know if there's a word for it but it's in so many songs spanning the history of recorded music that there has to be a word for it! So I'm wondering if any of you know what this is called or just what something similar to this little note/tonal trick is called. I've included five really obvious uses of the trick but there are so many more, so if more examples are needed to pinpoint what this is, let me know!
Most clear example: 0:40 to 0:49 (and repeated throughout song) of Baby by Os Mutantes
More examples: 0:43 to 0:50 of Mr. Maker by the Kooks
0:24 to 0:36 of In an Aeroplane Over the Sea by Neutral Milk Hotel
0:00 to 0:20 of Dead Record Player by Dr. Dog and the repeated slide-note throughout the song
0:32 to 0:42 & 1:05 to 1:15 of (Dee Dee) Be My Girl by Dee Dee Sharp