Binaural TFS (bTFS) and Monaural TFS (mTFS)
Speech recognition can benefit from Binaural processing of TFS (bTFS) in two ways: 1) sensing the same TFS in both ears could be an indication that the sound is originating from a single source, and 2) the time difference between the two TFS signals could help the listener to localise the source. The ordering of the tone-vocoding and the spatial simulation allowed us to isolate the bTFS and mTFS contributions in the three conditions shown in Figure 2.
When the tone-vocoding takes place prior to applying the HRTFs, the signal reaching the ears has artificial TFS, but normal spatial properties (vocBefore). When the tone-vocoding takes place after applying the HRTFs, the signal reaching the ears has artificial TFS and ITD's. Both conditions maintain the interaural level differences. Therefore the contrast between unprocessed and vocBefore simulates mTFS removal, and the contrast between vocBefore and vocAfter simulates bTFS removal.
Figure 2: Illustration of how the sequence of tone-vocoding and spatial simulation isolates monaural TFS and binaural TFS