Bulkheads: Sound radiation efficiency – Laboratory testa (NT ACOU 033) Posted onSeptember 15, 1980July 15, 2020Author Report #: NT ACOU 033 Approved: September 1980 Download pdf Size: 153.76 KB Abstract This NORDTEST method describes a laboratory method of measuring the sound radiation efficiency of bulkheads, when excited mechanically into resonant, flexural vibrations.