The classical cabaret song essentially a standards-era pop song written by a classical composer is a small but fascinating slice of the classical vocal repertoire, a medium in which classical composers both link themselves to the vernacular musical language and comment on it. Even so resolute a modernist as Arnold Schoenberg wrote a few. Bolcom's, with texts by Arnold Weinstein, show the influence of Charles Ives. Their straightforward tunes set wry romantic lyrics of middle age, portraits, or gnomic little stories. Many of the songs are quite funny; some open up the chasms of sadness and mystery that lie under everyday human lives. The piano accompaniments live a life of their own, sometimes giving simple harmonic support to the tune but more often running in parallel with it somehow perhaps in harmonically dense runs that suggest life's larger dimensions. From their popular antecedents these songs borrow a conversational quality, shifting periodically between melody and spoken or half-spoken text.
Such pieces are often performed by singers with chamber-size voices (Kerrytown Concert House is a frequent local cabaret-song venue), but I'm betting that Bolcom's are going to get their definitive performance in the larger scale of Brueggergosman's April concert. She has all the ingredients she needs to make that definitive performance: the vocal agility, the humor, the ability to tap into the African American roots that shape the melodies and ragtime rhythms of Bolcom's songs, and most of all the quality that used to be called personality, which is different from sheer charisma and which ought to let her draw the crowd into the intimate quality of these songs even in a hall the size of Hill Auditorium.