This paper reports a series of experiments with text-to-speech (TTS) voices. These experiments have been conducted to develop audio materials for listening comprehension as an alternative technology to traditionally used audio equipment like the compact cassette. The new generation of TTS voices based on unit selection synthesis provides impressive naturalness and intelligibility. In the experiments, TTS-generated audio files have been put to use in the classroom procedure and listening tests. So far, these endeavours have yielded positive results. The paper also evaluates the synthesised speech involved in the experiments and discusses problems that arise in the application.