In a semi you would generally have a room or two not connected to your neighbours property. Use those if you must. In an old terrace, and a lot of older semi's, the party walls will probably be of double brick or brick and breeze block construction so noise leeching through is rarely a problem. You may be worrying over nothing. Have you tried asking the neighbours if they can hear you, and if they can, whether you can pick times when it does not matter? Sounds a cheaper option to me.

Cheers

DtG