1. A computer system comprising: a central processing unit for processing a presentation of visual content and audio content using: a Visual Browser for visually presenting visual content retrieved from a computer communications network; a Voice Browser for audibly presenting voice content retrieved from said computer communications network; and, a Coupling Interface for synchronizing said visual and audible presentation of said visual and voice content in each of said respective Visual and Voice Browsers; wherein said Coupling Interface is configured to retrieve a network-based document formatted for display in the Visual Browser, to identify in the retrieved document a reference to the Voice Browser, the reference specifying electronic content formatted for audible presentation in the Voice Browser, and, to transmit the reference to the Voice Browser; wherein the Voice Browser is configured to retrieve the specified electronic content and audibly present the electronic content in the Voice Browser; wherein the Visual Browser is configured to visually present the network-based document concurrently with the audible presentation, the step of concurrently presenting resulting in a multi-modal presentation of the retrieved network-based document, the multi-modal presentation having a visual modality and an audible modality, functions for the visual modality being provided by the Visual Browser and functions for the audible modality being provided by the Voice Browser.