What are Intersensory Associations?
A more common terminology regarding 'intersensory associations' is multisensory or crossmodal integration. Crossmodal integration takes place in the association cortices in the brain (Fig. 1). An example is the coupling of auditory and visual input during lip reading, as mentioned in the comments. Lip reading can aid in acoustic speech understanding, especially so in the hearing impaired. 

The association cortices include most of the cerebral surface of the human brain and are responsible for integrating the sensory input that arrives in the primary sensory cortices. The diverse functions of the association cortices are loosely referred to as “cognition,” which literally means the process by which we come to know the world. Cognition enables us to attend to external stimuli, to identify the significance of stimuli and to plan meaningful responses to them. The association cortices receive and integrate information from a variety of sources and in turn influence a range of cortical and subcortical targets (Purves et al., 2001). 


Fig. 1. Association cortices. source: Brown, Physiology &amp; Neuroscience websites 

Reference
- Purves et al., Neuroscience, 2nd ed. Sunderland (MA): Sinauer Associates; 2001