We have found one software suitable in our database for this conversion.
xls to mp3 conversion seems to be highly unusual, but apparently not entirely impossible.. However, you can find websites such as Tripd, that allow users to process properly formatted Excel spreadsheets (.xls, .xlsx) and transcript the audio to MP3 format, thus basically making spreadsheet to audio conversion possible.
Other than that, we do not really know about any other possible way how to convert xls to mp3.
XLS
Files with xls extension are best known as spreadsheets from Microsoft Excel. A spreadsheet is basically a grid of cells sorted in rows and columns. Each cell can contain text, numeric or formula data. Excel XLS spreadsheets can be opened in most other similar programs, such as OpenOffice.org Calc.
MP3
The mp3 file extension is traditionally used for one of the most common types of compressed audio files, MP3s, which you can playback using almost any media player.