Abstract: The New National Theatre opera house (NNT opera house) seats 1810,its volume is 14500 m³,and its reverberation time,with audience,is 1.5 s (proscenium curtain open).The main floor is almost rectangular,the three balconies have modest fan shape in plan,although the balcony facia at each level create a rectangular shape.The unique design has a large curved reflector in front of and above the proscenium and six curved reflecting surfaces at the front ends of the three side balconies to form,in combination,an'acoustic trumpet.'Three surfaces,along with the balcony faces and the shaped ceiling,distribute,without aid of electro-acoustic equipment,the singers'voices uniformly over the seating areas from a large portion of the large stage at sound levels that easily override the orchestra in the pit.