There are two defining features of Sallie Ford & The Sound Outside: their vintage rockabilly sound and Sallie’s loud, strong voice. The Portland band definitely takes influence from the good ol’ days of the ‘50s, both musically and stylistically, as the music has a raw, old-school sound furnished with classic reverb guitars and a frontwoman who has a penchant for horn-rimmed glasses and a curly bob hairdo. But on the other hand, there is something wildly cutting edge about Sallie’s racy lyrical content. Witness this amalgamation of eras at Pier 84 as part of the free RiverRocks Festival on July 11 at 6 p.m.