Acoustical design was completed by acoustical consultant Kirkegaard Associates. Applications of underwater sound can be found in sonar, acoustic communication and acoustical oceanography. Acoustical engineering is the study of Sound and Vibration. Floyd Toole has extensively evaluated loudspeakers in acoustical engineering research. There are acoustical wall carpets to reduce sound. It has improved acoustical insulation compared to its predecessor. Inaccurate reproduction of the voice coil signal results in acoustical distortion. It has low moisture absorption, and exceptional acoustical and electrical properties. In phase conjugating mirrors based on stimulated Brillouin scattering optical vortices excite acoustical vortices. Fabric covered panels are one way to heighten acoustical absorption. Perceived "loudness" varies approximately logarithmically with acoustical output power. The Pythagoreans focused on the mathematics and the acoustical science of sound and music. Finish materials often consist of fabric, wood or acoustical tile. After examining existing optical and acoustical equipment, Lobanov also turned to radio-location techniques. This knowledge is applied in acoustical engineering to study how to quieten aircraft.