Supporting deaf and hard-of-hearing (D/HH) people is a crucial social welfare measure. However, currently, communication support for D/HH people is insufficient for a conversation with multiple hearing people. In order to support D/HH people in these situations, this paper proposes a multi-modal speech visualization application, named Mieta, which provides various aspects of information about speech content. For the purpose of evaluating how actually useful the Mieta is, we conduct an evaluation experiment with actual nine D/HH students. As a result, Mieta contributes significantly to understanding, although it increases misunderstanding for D/HH people when there are voice recognition errors. Furthermore, subjects find that the Mieta's strength lies in its main characteristics, which includes multimodal speech visualization, whereas some find weakness in its voice recognition performance speed.