# Welcome to the Highcharts Gantt JS (gantt) Options Reference

These pages outline the chart configuration options, and the methods and properties of Highcharts objects.

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# sonification.defaultSpeechOptions.mapping

Mapping configuration for the speech/audio parameters.

All parameters except `text` can be either:

- A string, referencing a point property to map to.
- A number, setting the value of the speech parameter directly.
- A callback function, returning the value programmatically.
- An object defining detailed configuration of the mapping.

If a function is used, it should return the desired value for the speech parameter. The function is called for each speech event to be played, and receives a context object parameter with `time`, and potentially `point` and `value` depending on the track. `point` is available if the audio event is related to a data point, and `value` is available if the track is used for a context track using `valueInterval`.