Senior designers within a company are responsible for the conceptualisation of ideas and designs to be used as the solution to a creative problem from beginning to end. They generally have five or more years experience in the required field of work in lower positions.This title give the designer more authority over design decision making and giving direction to the junior and or mid weight designer.Both the junior and mid- weight designers in the studio report to the senior designer for information and direction as to where the design is going and how it is being formed, these designers generally are responsible for the more hands on aspects of creation the design.As the senior is able to direct the junior\mid weight designers , they tend to and are expected to interact more directly with the clients, which includes talking to them and making revisions.Interpreting briefs is part of a senior designers day to day job as it is important that the final art incorporates the concept of what the client wants in an effective way. It is also important that it is ensured the art is created within the budget and time allowed.
sources:
http://fineartamerica.com/featured/conversation-karl-addison.html
http://terriphathanathong.wordpress.com/2011/09/15/drawing-class/
Alison- My design career blog 