A Speaking Rate Adjustable Digital Speech Repeater for Listening Comprehension in Second-Language Learning

The paper introduces a speech repeater system, which can adjust speaking rate with TD-PSOLA algorithm, for second-language learning. According to the average mean opinion score (MOS) testing results, the MOS of the modified speech by the system achieve 4.1, which is close to the quality of the original voice. The relationship between speaking rate and listening comprehension is also studied with the system. The comprehension test shows that the slower the speaking rate is, the higher the comprehension level of the subject becomes. When the speaking rate over slow, however, the comprehension level decreases to a certain extent. The listening comprehension test also shows that as the speaking rate becomes slower, the comprehension accuracy increases.