The specialists likely to be called in to assist the surveyor will either be fellow professionals or contractors or tradespeople. An acoustics engineer may be required where there is doubt about the sound-proofing of a separating or party wall, or where the acoustic performance of special spaces, such as an auditorium or meeting hall, requires assessment. In some situations a general contractor may be the most appropriate person to undertake drain testing, but there are specialist contractors who may be able to undertake this work more competitively. The surveyor is expected to identify whether any insect infestation is active or not, and to distinguish between the various types of insect, but a specialist contractor should be consulted regarding the estimated cost of remedial work. A client is unlikely to be impressed if, after waiting some time for a survey report to arrive, they discover that it is merely a list of specialists to be consulted.