21. Measurement of airborne noise emitted by machines ; enveloping surface method ; metal working machines , drilling machines 22. Measurement of airborne noise emitted by machines ; enveloping surface method ; woodworking machines sanding machines 23. Measurement of airborne noise emitted by machines ; enveloping surface method ; woodworking machines ; routing machines 24. Measurement of airborne noise emitted by machines ; enveloping surface method , woodworking machines , planing machines 25. Measurement of noise emitted by machines ; airborne noise emission ; enveloping surface method ; surface treatment plants 26. Measurement of airborne noise emitted by machines ; enveloping surface method ; metal working machines grinding machines 27. Measurement of noise emitted by machines ; airborne noise emission , enveloping surface method ; internal combustion engines 28. Measurement of noise emitted by machines - airborne noise emission enveloping surface method - part 23 : gear transmisson 29. Measurement of airborne noise emitted by machines ; enveloping surface method ; surface treatment plant ; measurement example 30. Measurement of airborne noise emitted by machines ; enveloping surface method ; still picture and motion - picture projectors
