Over the last few years I have attended performances of opera and art song recitals which have been recorded. However the sound recordings sometimes don't match what I have heard in the hall, and I have noticed that both sustained high notes and low notes can sound off pitch on the recording but which were perfectly fine in the venue. What is going on? I wondered whether this is because fewer recording engineers have experience and training in recording such voices (I don't for sure), as the same problems do not occur with instrumentalists as these can be recorded dry. Why is it that these differences occur in the recording? What can we as recording engineers do to combat these problems?