Acoustics in auditoriums is greatly dependent on the reverberation time, thus, the optimum reverberation time of an auditorium is dependent on the use for which it is designed for.
Optimum reverberation time is a compromise between clarity (requiring short reverberation time), sound intensity (requiring a high reverberation level), and liveliness (requiring a long reverberation time).
In order to modify the reverberation time to the required levels acoustic treatment is required. Fabric wrapped or wooden acoustic panels are often the method to reach to the accepted reverberation time.
Some indicative applications from auditorium treatments are shown on the top of this page.