A supercharger for a vehicle includes a lower body housing a compressor and an upper lid having a contraction chamber. The upper lid includes an air circulation port and is configured to be coupled to the lower body thereby forming a plenum. The contraction chamber is integrally formed in the upper lid adjacent to the air circulation port and includes an attenuator plate that defines a tuning neck. The tuning neck defines an inlet to and part of a volume of the contraction chamber, and includes a predetermined size and shape configured to attenuate a desired sound frequency generated by operation of the supercharger.