The invention claimed is:1. A pressure wave generating element comprising:a support;a heat generating layer disposed on the support and configured to generate heat by energization;a pair of electrodes disposed on a surface of the heat generating layer opposite the support,wherein the heat generating layer includes a fiber with at least a partial metal coating on a surface thereof, andwherein the partial metal coating has a thickness that increases with an increasing distance from the support.2. The pressure wave generating element according to claim 1, wherein the thickness of the metal coating is a largest distance on the surface of the fiber that is opposite the support.3. The pressure wave generating element according to claim 1, wherein the metal coating has a thickness T1 at a position closest to the support, and has a thickness T2 at a position farthest from the support, and T1<T2.4. The pressure wave generating element according to claim 1, wherein the metal coating is not disposed on the surface of the fiber that is closest to the support.5. The pressure wave generating element according to claim 1, wherein the fiber comprises a polymer fiber.6. The pressure wave generating element according to claim 1, wherein the fiber comprises a plurality of fibers and an average fiber diameter of the plurality of fibers of the heat generating layer is 1 nm or more and 1000 nm or less.7. The pressure wave generating element according to claim 6, wherein the average fiber diameter is 15 nm or more and 500 nm or less.8. The pressure wave generating element according to claim 1, wherein the fiber comprises a plurality of fibers and beads are contained in a part of the fibers.9. A pressure wave generating element comprising:a support;a heat generating layer disposed on the support and configured to generate heat by energization;a pair of electrodes disposed on a surface of the heat generating layer opposite the support,wherein the heat generating layer includes a plurality of fibers and beads, with the plurality of fibers having at least a partial metal coating on a surface thereof, andwherein the plurality of beads are sandwiched between the plurality of fibers having the partial metal coating disposed thereon.10. The pressure wave generating element according to claim 1, wherein the support comprises a flexible material.11. The pressure wave generating element according to claim 1, wherein the support comprises one of a semiconductor or an electrical insulator.12. The pressure wave generating element according to claim 1, wherein the heat generating layer comprises a conductive material and is configured to emit a pressure wave due to periodic expansion and contraction of air.13. The pressure wave generating element according to claim 1, wherein the fiber comprises a plurality of fibers of a nonwoven fabric that is bonded or intertwined by one of a thermal, mechanical or chemical action into a sheet shape.14. The pressure wave generating element according to claim 1, wherein the fiber comprises a plurality of fibers of a woven fabric in which warps and wefts are combined.15. The pressure wave generating element according to claim 1, wherein the fiber comprises a plurality of fibers forming a knitted fabric.16. A pressure wave generating element comprising:a support;a heat generating layer disposed on the support and configured to generate heat by energization;a pair of electrodes disposed on a surface of the heat generating layer opposite the support,wherein the heat generating layer includes a fiber with at least a partial metal coating on a surface thereof, andwherein the pair of electrodes are disposed on opposing sides of the surface of the heat generating layer.17. The pressure wave generating element according to claim 16, wherein the pair of electrodes each have a comb-shaped electrode structure.18. The pressure wave generating element according to claim 16, wherein the partial metal coating has a thickness that increases with an increasing distance from the support.19. The pressure wave generating element according to claim 16, wherein the partial metal coating has a thickness that increases with an increasing distance from the support.20. The pressure wave generating element according to claim 16, wherein the fiber comprises a plurality of fibers of a nonwoven fabric that is bonded or intertwined by one of a thermal, mechanical or chemical action into a sheet shape.
