Another common cause of spoke 'pinging' is loose spokes. It doesn't hurt to check that.
Dan Artley, Parkton, MD, USA
Thanks Doug and others that responded for help in tracking-down my "spoke pinging" problem. Closer inspection of removed wheel revealed a very slightly bent front axle as well as an occasional hang-up of hub bearing as cause of problem. I believe that when riding and hang-up occurred and released the resulting vibration wave was transmitted to the spokes. I did neglect to check straightness of front axle when rebuilding so senior moment strikes again.