The web offers rich visual content, and for many web designers it is the visual domain that dominates their practice. Yet sound, music and audio all play a significant role in the human sensory systems, in some cases sound can be more powerful, especially to emotionally influence viewers. This paper looks at the relationship between audio and visual elements in web content. In particular looking at the power of synchronization of audio and visual content. Bringing together the sensory experience from the two sensory systems to potentially enhance the users overall experience. The relationship between audio and visual elements, and more importantly their level of synchronization was explored through an experimental trial where users were exposed to web content with differing levels of synchronization between the audio and visual components. User feedback from these trials showed that synchronization played a key role in the content that users selected as their preferred items. From these results, several new principles for the effective design of web based audio-visual elements were developed including linking the nature and complexity of the visual forms, to the nature and complexity of the audio forms, to provide greater synchronization and enhance overall user experience.