US Patent 7724913 Composite damper for speaker

A composite damper for a speaker comprises an inner ring surface material, an outer ring surface material, and a plurality of ribs connected between the inner ring surface material and the outer ring surface material. The inner ring surface material and the outer ring surface material have a plurality of alternating concentric peaks and valleys; thereby when it is coupled with a periphery of a voice coil of the speaker, it has a more stable vibration frequency.