In today’s instant-gratification world, it is difficult to accept that some things still take time. But in Philadelphia, the team behind the Philadelphia Orchestra’s 2-year-old Kimmel Center for the Performing Arts is still tweaking and adjusting the hall’s acoustics, striving to create one of the world’s great concert venues. “Almost two years after opening night, hundreds of millions of dollars since the orchestra started dreaming of acoustical perfection, Verizon Hall isn’t quite what it should be, Kimmel and orchestra leaders agree… And so the original acousticians for the hall, Artec Consultants, are being brought back for another round of work.”