It is assumed that the songs of Bay-capped Wren-Spinetail are inherited, not learned, as probably is the case for other furnariids. The primary song of the wren-spinetail is an insect-like trill, 2-3 s long, repeated several times.
For a representative audio recording with sonogram, see audio
Other vocalizations include short alarm or contact calls and a chattering song often produced between trills or in flight. Songs and calls are simple and probably the repertory size is small, consisting of two-three songs. Unfortunately there are no published papers on song function, repertory or sexual differences. Geographic variation in song characteristics seems to be unlikely due its limited distribution; however, since wren-spinetails are habitat specialists of brackish and fresh water marshes, isolation of some populations may have produced song variation across its range.