A brake disc assembly ( 22 ) for a vehicle includes a ventilated rotor ( 24 ) defined by vent holes ( 42 ) between inboard ( 32 ) and outboard ( 34 ) friction plates. The vent holes ( 42 ) are separated by ribs ( 40 ) spaced in regular circumferential increments about the rotor ( 24 ). The rib pattern ( 40 ) is divided into two or more sectors ( 48 ) of equal angular measure. Within each sector ( 48 ), an attenuation region ( 50 ) interrupts two or more ribs ( 40 ) by replacing the ribs ( 40 ) with a cluster of individual pins ( 54 ) which may be arranged in radial and circumferential rows. The pins ( 54 ) can have consistent circular or varying cross-sectional configurations. Each attenuation region ( 50 ) spans a territory within each sector ( 48 ) that is preferably at least 20% and less than 55% of the sector ( 48 ) real estate. The rotor ( 24 ) completely or at least substantially eliminates vibration modes in objectionable, audible frequencies without adversely affecting the structural integrity, cooling capabilities or functional attributes of the disc brake assembly ( 22 ).