Developments in Mobile Computing are putting pressure on the software industry to research new modes of interaction that do not rely on the traditional keyboard and mouse combination. Computer users suffering from Repetitive Strain Injury also seek an alternative to keyboard and mouse devices to reduce suffering in wrist and finger joints. Voice-control is an alternative approach to spreadsheet development and debugging that has been researched and used successfully in other domains. While voice-control technology for spreadsheets is available its effectiveness has not been investigated. This study is the first to compare the performance of a set of expert spreadsheet developers that debugged a spreadsheet using voice-control technology and another set that debugged the same spreadsheet using keyboard and mouse. The study showed that voice, despite its advantages, proved to be slower and less accurate. However, it also revealed ways in which the technology might be improved to redress...