Okay, in some phrases the voice just doesn't come out. But have you wondered why? Have you ever tried singing for about 70 years or more?
As you know, the vocal cords are not eternal, (of course) and at the age of 80 it is more than normal for there to be a loss of voice such as for sight or other damage.
Many forget that this Gentleman started screaming rock 'n' roll since he was around 12 years old. And at the time the amplification systems were little more than megaphones, if there were any.
However, Paul McCartney is a wonder of nature. If you just consider how many cigarettes the Beatles smoked, not to mention the cannabis, which he gave up only few years ago.
1965 and before. Early Paul. He was still exploring his range and did not have as much control or move as easily between styles within the same song.(quora.com)
All of his power and range are there. Maybe I'm Amazed is a highlight but numerous other examples from Oh Darlin to Call Me Back Again. Even trifles like the cover of Love Is Strange on Wild Life are amazing performances. The world tour tested his voice and brought it back to reality.
You can hear that inexorable process play itself out in singers who keep at it long past their prime. In his youth, Paul McCartney produced a wondrously pure schoolboy tenor, with a touch of sandpapery sexiness. At 74, he can still usually hit the high note on “night” in the opening line of “Blackbird,” but the lightness has Paul been scrubbed away, replaced by an uncertain warble. There is almost always a trade-off between agility and age. Singers don’t want to retire, and fans don’t want to lose them, but the price of longevity can be steep. (Vulture)
