  An important concept in organisational behaviour is how hierarchy affects the
voice of individuals, whereby members of a given organisation exhibit differing
power relations based on their hierarchical position. Although there have been
prior studies of the relationship between hierarchy and voice, they tend to
focus on more qualitative small-scale methods and do not account for structural
aspects of the organisation. This paper develops large-scale computational
techniques utilising temporal network analysis to measure the effect that
organisational hierarchy has on communication patterns within an organisation,
focusing on the structure of pairwise interactions between individuals. We
focus on one major organisation as a case study - the Internet Engineering Task
Force (IETF) - a major technical standards development organisation for the
Internet. A particularly useful feature of the IETF is a transparent hierarchy,
where participants take on explicit roles (e.g. Area Directors, Working Group
Chairs). Its processes are also open, so we have visibility into the
communication of people at different hierarchy levels over a long time period.
We utilise a temporal network dataset of 989,911 email interactions among
23,741 participants to study how hierarchy impacts communication patterns. We
show that the middle levels of the IETF are growing in terms of their dominance
in communications. Higher levels consistently experience a higher proportion of
incoming communication than lower levels, with higher levels initiating more
communications too. We find that communication tends to flow "up" the hierarchy
more than "down". Finally, we find that communication with higher-levels is
associated with future communication more than for lower-levels, which we
interpret as "facilitation". We conclude by discussing the implications this
has on patterns within the wider IETF and for other organisations.
