In this scientific journal article you can actually hear male mice sing, once they have been confronted with the sent of a female mouse.
Previously it was shown that male mice, when they encounter female mice or their pheromones, emit ultrasonic vocalizations with frequencies ranging over 30–110 kHz. Here, we show that these vocalizations have the characteristics of song, consisting of several different syllable types, whose temporal sequencing includes the utterance of repeated phrases. Individual males produce songs with characteristic syllabic and temporal structure.
The audio player did not work in my browser – the wav files played nicely.