Deborah Humble will give the Australian premiere of a work Mendelssohn didn’t want you to hear.

A recently rediscovered song Des Menschen Herz ist ein Schaht (A Man's Heart is like Mine) by Felix Mendelssohn will have its Australian premiere this Wednesday at Sydney Conservatorium's Verbrugghen Hall courtesy of leading mezzo soprano Deborah Humble.

Scored for alto voice and piano accompaniment, the work is only 29 bars in length and in the key of A flat major. The original manuscript, a commission for the composer's friend Johann Valentin Teichmann to a text by Friedrich Rückert, was found in a private American collection after being considered missing for the past 140 years.

A letter from Teichmann included among the rediscovered documents asks that Mendelssohn not circulate the work, due to it being a 'private' commission. It would appear that Mendelssohn complied with Teichmann's request to the best of his ability – records indicate that the manuscript had only previously been sold at auction twice, in 1862 and again in 1872.

On May 6, an exclusive performance of the work was given by Amy Williamson and pianist Christopher Glynn on BBC Radio 4. For Australian audiences, Deborah Humble and pianist Stephen Mould will include the lost song in a program which also features Richard Wagner's Wesendonck-Lieder and songs by Johannes Brahms.

Humble and Mould perform Mendelssohn, Wagner, Brahms Wednesday May 28.