A multi-ribbed power transmission belt having longitudinal grooves and transverse grooves that form a plurality of cogs on the belt surface defined between adjacent transverse grooves is provided. The pitch lengths of the rows of cogs are randomized or sequenced over the entire length of the belt to reduce the noise of the belt as it travels about its associated pulleys. The ideal pitch pattern on a belt is variable, dependent upon the circumferential length of the belt. To create an optimized pitch sequence for belts of various circumferential lengths, a method of manufacture is employed wherein a portion of the pitch sequence of a shorter belt is incorporated within an optimized pitch sequence of a longer belt and both belts are manufactured from a single mold. The longer belt may contain cogs of various shapes intended to offset a range of frequencies and minimize noise generation. By selecting a certain span of the longer belt for the creation of smaller belt(s), a single mold may be utilized for producing belts of varying length and the noise characteristics of the belt may be controlled and optimized.