Voice can be active or passive.
Note 1: The term can also be used to mean ‘student voice’ or ‘academic voice’ where it means the individual voice of the writer, not a description of the verb or tense.
Note 2: The passive voice is used in academic writing as it is more formal, avoiding the first person form of the verb, which gives an impression of subjectivity.
Note 3: The passive voice can be used in any tense.
i.i Active Voice:
I then took measurements every second.
i.ii Passive Voice:
Measurements were taken every second.
Note: the passive voice is very commonly used in academic engineering writing.