Separate Ways Vowel Modifications

Hi greetings from Singapore,
I want to ask about vowel modification. Does Ken use the modified vowel "ooh" like "who" in the B4 note in this video?
https://youtu.be/V1A4-GrT4C8
I want to ask about vowel modification. Does Ken use the modified vowel "ooh" like "who" in the B4 note in this video?

Comments
Feeling that its gone~
start from 1:06 sustained B4 note