5. The method according to claim 1 wherein the reading scan rate is a page turn rate and determining the page turn rate comprises: processing the movement of at least one eye from the eye tracker to detect page change eye movements, the page change eye movements indicative of the user changing a reading position in the electronic text from an end of a current page of the electronic text to a start of a next page of electronic text; determining the user's page turn rate based on a time interval between detected page change eye movements, the page turn rate being a numerical value indicative of a number of pages a user reads per unit of time; and calculating an estimate of the user's reading speed based on the page turn rate and supplementary scan rate data indicative of the average or actual quantity of electronic text per page.
1. A method for displaying electronic text and synchronizing playback of a soundtrack for the electronic text, the soundtrack comprising multiple audio regions configured for playback during corresponding text regions of the electronic text, each audio region being defined by audio data comprising: an audio track for playback in the audio region, a start text position indicative of a word in the electronic text corresponding to where playback of the audio track is to begin; and a stop text position indicative of the word in the electronic text comprising to where playback of the audio track is to cease, comprising: displaying at least a portion of the electronic text on a display; tracking a movement of at least one eye of a user with an eye tracker to detect at least one of a predetermined type of eye movements; determining a reading scan rate of the user based on the detected type of eye movements and a timer, the reading scan rate being a value indicative of a number of eye movements per unit of time without requiring detection of an exact position of a user's gaze within the electronic text; calculating an estimate of the user's reading speed based on the determined reading scan rate and supplementary scan rate data relating to the electronic text and/or user that is indicative of an actual or average quantity of electronic text per detected type of eye movements; updating a user reading speed variable representing the user's reading speed based at least partly on the calculated estimate of the user's reading speed; maintaining a reading position counter corresponding to an estimated text position indicative of a word in the electronic text that the user is currently reading, the reading position counter incrementing at a rate based on the user reading speed variable; and controlling playback of the audio track for the audio region of the soundtrack over an audio output system based on the audio data and on the reading position counter to synchronize playback of the audio regions with the user's estimated text position.