{HEAD ~ a noise reducing chamber} provided at {TAIL ~ an end portion} of the noise reducing groove and having a predetermined depth that is greater than a depth of the noise reducing groove 
{ HEAD ~ a noise reducing chamber } provided at { TAIL ~ an end portion } of the noise reducing groove and having a predetermined depth that is greater than a depth of the noise reducing groove
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH