I heard the Buff-breasted Babbler at a number of locations but spotting this under-growth specialist was tough. Rarely shows itself, and that in dark environments. The classical calls are easily identified once learnt.
Taxonomic Notes :
Note that the form buettikoferi is now treated as a separste species under the name Sumatran Babbler Trichastoma buettikoferi following Wells et al (2001) Systematic notes on Asian birds 21. Babbler jungle: a re-evaluation of the 'pyrrogenys' group of Asian pellorneines (timaliidae). - Zool. Verhand., Leiden, 335:235-252.