Jongen's piano chamber music is an audio recording of his selected works:
The Trio, chronologically the earliest of the described works, shows an early trend in Jongen's artistic activity, when the young composer, still a student at Liege conservatory, sought his own musical identity, naturally drawing upon the experiences of his great predecessors. This composition represents a current strongly linked to the tradition, both in relation to form and the harmonic devices applied. Stylistically, Trio is close to German post-Romanticism as well as the earlier French school. It shows the composer's predilection for connecting a simple, diatonic melody with more chromatic fragments. The uncommon melodic creativity, harmonic abundance, and the intensity of sound cause this composition to overflow with musical content and to constitute quite a challenge for both the performer and the listener.
The Sonata represents Jongen as a more mature artist, though still in search of his own path as a composer. Although it is not devoid of external influences and explicitly alludes to the aesthetics of Franck, the composition allows the singling out of a set of qualities typical of Jongenian musical language. An abundance of motifs, inexhaustible creativity in thematic work, and a melodic line (simple and rife with lyricism at the same time), as well as an inclination for the fullness of sound, create a characteristic musical picture of this work.
In both of these compositions, the narration is usually shaped through a melodic factor, and linearity is the superior value. Rich melodic invention is usually realized through seemingly never-ending phrases. Their specific structuring materializes in repetitions of short motifs, which in turn develop into a longer thought. Violent, dynamic changes are inseparable elements of musical discourse in Jongen's early and middle period of artistic activity, and often determine the emotional character of the compositions. A constitutive element, on which the narration is based, is undoubtedly a widely scoped dialogue between the instruments as well as the interdependence of the particular parts.
The Deux pieces show Jongen's new composing face, in which coloring and sound, now advancing to the forefront, replace post-romantic emotionality. Textural simplicity and extension of the major-minor system, which materializes in the application of a whole-tone scale as well as a pentatonic, define features of this new musical language, thus giving it a new dimension. Whereas new principles for the organization of the sound material develop, two observable narrative directions are determined by melody and color. The metamorphosis of the musical language goes along the compression of musical thought and the tendency to miniaturize the form or quam.