Our late friend, Rosie, raised this topic a couple of years ago, and as a result, John Martini met a young lady at a WNP Cliff House gathering who was doing doctoral research at Stanford on that very topic. After a series of emails, Lauren Lew came up to Santa Rosa one Saturday morning and recorded interviews with both my friend Linda and myself (both of us Sunset natives born in the early 1950s who had at least 1 parent from the Mission). Lauren asked a long series of questions about our family backgrounds, schools, moving, etc., and the interview ended with each one of us reading a long list of words to check pronunciation.
Her final product was a lengthy doctoral disseration, but the highlights were:
1) Yes, there is a San Francisco accent, similar to the East Coast, apparently the result of heavy concentrations of Irish immigrants. This is clearly beginning to die out.
2) Yes, we both had the SF accent, but we were both losing it after more than 10 years of living in Sonoma County (many flat Mid-western accents prevail here).
3) Our individual accents were also ever-so-slightly Germanic--explained by the presence of Linda's father in her household and my regular contact in my early years with my own maternal grandfather, both of whom had been born in Hamburg, Germany. Several words triggered this assessment--EXIT (pronounced EG-ZIT), UMBRELLA (pronounced with what almost sounds like an extra vowel between the B and the R), and something about our pronunciation of the letters D & T when they appear at the end of a word.
4) Even among Asian residents in the Outsidelands, Lauren found many of the traditional San Francisco inflections and variations in their pronunciation of English words. These almost always became more apparent, based on the length of time spent living in the neighborhood.
I have a 97-year-old former co-worker and Sunset neighbor who was originally born in North Beach to a Sicilian family, and she never spoke or heard English until she started grammar school, yet her English has been perfect since she was a girl. Other old Italians will sometimes catch her, though, saying she sounds slightly "different" from them, in either English or Sicilian. Reason--she married young & settled on 24th Avenue in the Sunset back in 1937 when virtually ALL of her neighbors were Irish transplants from the Mission, and she found no outlet in which to use her native language.
It always amazed me that some of my grandparents' friends were born in SF and NOT in Ireland--the brogue was so thick among those who were born South of Market, and who then moved en masse to the Mission after 1906, then to the West of Twin Peaks after 1946.