The author, on the basis of literature and his professional therapeutic experience, describes the meaning of vocal signals in diagnosing patients' problems and improving communication during a therapeutic dialogue. In the article the author also shows the influence of voice vocal features on evoking many nonspecific therapeutic factors as well as accelerating the insight and overworking process. The great importance of metasignals, i.e. information concerning emotions hidden in patient's utterance has been noticed. A therapist is able to recognize them by careful listening to all vocal signals, particularly to: speech rhythm, voice height and verbal intensifiers. The author indicates that vocal signals themselves may often influence the content of transmission and give a lot of reliable information about patients. Patients' reactions on a therapist's behaviour are highly influenced by the reception and evaluation of his/her vocal signals. Therefore, a therapist should more thoroughly analyse voice features present at a therapeutic interaction and become their conscious sender and recipient.