11. Measurement of airborne noise emitted by machines ; enveloping surface method ; packaging and allied machinery 12. Measurement of airborne noise emitted by machines ; enveloping surface method ; mine trackless vehicles 13. Measurement of airborne noise emitted by machines ; enveloping surface method ; diesel traction trolleys 14. Measurement of noise emitted by machines ; airborne noise emission ; enveloping surface method ; cooling towers 15. Measurement of airborne noise emitted by machines ; enveloping surface method ; continuous handling equipment 16. Measurement of airborne noise emitted by machines ; enveloping surface method ; food , drink and allied machinery 17. Measurement of noise emitted by machines ; airborne noise emission ; enveloping surface method ; outboard motors 18. Measurement of airborne noise emitted by machines ; enveloping surface method ; cartridge - operated fixing tools 19. Measurement of noise emitted by machines ; airborne noise emission ; enveloping surface method ; hydraulic assemblies 20. Measurement of airborne noise emitted by machines ; enveloping surface method ; metal working machines ; milling machines