The individual vocals and group harmonies that grace On the Rock, the latest from Jamaican trio Israel Vibration, are as sparkling as ever: Here, Skelly Spence, Apple Craig, and Wiss Bulgin deliver the mellifluous, emotive phrasing that has endeared them to reggae harmony fans for nearly two decades. Unfortunately, dulcet singing alone doesn’t guarantee a great album. Uptempo tracks “Sugar Me” and “Rudeboy Shufflin’ ” are satisfying, but too much of Rock is characterized by clichéd, hookless arrangements, generic platitudes about love and brotherhood, and assembly-line studio musicianship.