Instrument and experiencer.
instrument.
If an agent uses another entity in order to perform an
action, that other entity.
experiencer.
When a noun phrase is used to designate an entity as
the person who has a feeling, perception or state.
In the sentence The boy feels sad, the experiencer (The
boy)is the only semantic role. In the question, Did you
hear that noise?, the experiencer is you
and the theme is that noise.