1. A method comprising: receiving first data indicative of pressure measurements and measurements of components of a particle motion vector acquired by sensors disposed on at least one cable, the components comprising at least a cross-line component relative to a direction in which the at least one cable extends; processing the first data on a machine to construct an in-line component of the particle motion vector based at least in part on the cross-line component of the particle motion vector and the pressure measurements, the in-line component being represented by second data and the in-line component being associated with the direction in which the at least one cable extends; and processing the first and second data in a geophysical processing operation that relies on at least three components of the particle motion vector.