Alec Baldwin will narrate an October outing of New York Philharmonic’s “Inside the Music” series, focusing on Antonin Dvorak’s 1893 Symphony No. 9, “From the New World.”Multimedia presentation, written and produced by Joseph Horowitz, will include a full perf of the symphony conducted by Marin Alsop. Bass Kevin Deas will sing, as well as portray Dvorak and other characters from the era. Stage credits for Baldwin, who just earned an Emmy on Sunday his role in NBC’s “30 Rock,” include recent Roundabout productions of “Entertaining Mr. Sloane” (2006) and “The Twentieth Century” (2004). “Inside the Music” is skedded for Oct. 10 at Avery Fisher Hall.