Piezo-film speaker and speaker built-in helmet using the same

   
   

A flat piezo-film speaker is mounted in a motorcycle helmet. The flat-piezo film speaker is formed from a flat piezo-film curved in one direction to form at least one curved portion. A radius R of curvature at the curved portion is larger than at least 200 mm, preferably, in a range of 210 mm.ltoreq.R.ltoreq.360 mm. The piezo-film speaker built into a helmet for a motorcycle rider is capable of reproducing sound at a sound pressure sufficiently audible even when running the motorcycle and at a high tone quality.

 
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