The effects of the speaker's adjustment of the teaching strategy and the use of paralanguage information of speech to acquire its meaning were clarified by means of experiment: In the experiments, two subjects played a game of Pong: one of the subjects (operator) could not understand linguistically what the other one (teacher) was saying. The results of these experiments revealed the following. First, the teacher's high-pitched voice drew attention of the operator's current action. Second, the process of meaning acquisition can be regarded as reinforcement learning based on a multi-reward system (i.e., a positive reward for correct actions and a negative reward for incorrect actions, given in the form of the teacher's high-pitched voice). Finally, mutual adaptation between the subjects was observed, that is, the subjects learned to respond appropriately to each other's behavior. It is concluded that the above three phenomena are important to the process of meaning acquisition and can be viewed as the basic requirements to enable the acquisition of meaning of unknown speech, and to construct an adaptive sound interface, which can provide a natural interaction enviromnet for its user.