Use the active voice whenever the passive voice is not appropriate. Active verbs make for concise prose; sentences with passive verbs use more words. Moreover, passive verbs deemphasize or even eliminate mention of the performer of the action conveyed by the verb. See Voice.
In this project, three psychological experiments were performed
by the authors so that the technical problems for the auralization of
a sound field could be clarified.
In this project, the authors performed three
psychological experiments to clarify the technical problems
for the auralization of a sound field.
The matter of personnel health hazards associated with airborne free
chlorine or other gases apparently has not been considered in
this excavation plan. [Note that the indirect wording has left out the
main agent (the excavation planners).]
Excavation planners apparently have not considered how airborne free chlorine or other gases might cause health hazards to personnel.