“…It has been shown by many authors eg. Guy & Mulholland [5], that the position ofthe panel under test has a signi cant affect on the resultant sound reduction index, below the critical 'equency of the panel, As a result ofthe above observation it is obvious that in performing an experimental investigation into the e ect of different forms of incident eld on the SR] of a panel it would be necessary to minimise the e ects of room volume, panel area and aperture depth.…”