A very effective external swiftlet music / sound that attract swiftlets and encourage them to stay and nest.Since birdnests farmers started to use audio system to attract swiftlets into their birdhouses, many varieties of swiftlet sound have been created. Nowadays, the two main ones are the external and internal sound.The external sound, as the name implies, are to be used at the exterior of a birdhouse. It is a mixture of adult birds and baby birds chirping. Its main function is to attract swiftlets to the vicinity. This is a very important sound since if the sound is not done properly, no birds will come to your house, or even worse, the birds will be scared away. From experience, we are able to recognise good sound from the bad ones. We have tried more than 48 external sound from a variety of sources. Some are given by friends, some are purchased online, some are bought from Indonesia and Vietnam, even some are recorded and mixed ourselves. Some sound are very good at attracting birds to come to your house, but fail to convince them to stay. Some are better at expediting the nests making process