RJ Walker of the Mancy Podcast answered a listener’s question regarding how accents in the United States have changed since the 1990s. Walker explained that this “California Shift” has a great deal to do with such subcultures as skateboarding, surfing, snowboarding, and others that came to fruition during that time period within California.
What really clinched this specific lilt were the punk rock bands from California who were trying to sound British and the British punk rock bands trying to sound American. This shift or the “California Lilt” causes vowels to be elongated with different mouth shapes used to voice them.
Some linguists believe that pop punk and punk rock, in general, has a lot to do with this. American bands were trying to copy the sound of British punk bands and British bands were copying the American bands, and back and forth it went.