No need to convert, according to the PowerPoint help file your MP3 is already compatible with the program.
The tables below show the audio and video file formats that you can use in
Microsoft Office PowerPoint 2007. If you do not see a file format listed below, you will not be able to play the sound or movie file in a PowerPoint 2007 presentation unless you first convert the file to a supported file format. You can convert your file to a supported file format by using programs, utilities, or add-ins, other than PowerPoint 2007, such as the following:
PFCMedia PFCMedia is an add-in that automates the formatting of multimedia. For more information, see PFCMedia for PowerPoint.
Microsoft Windows Media Encoder Windows Media Encoder is a free program that makes some files compatible with PowerPoint 2007. For more information, see Microsoft Windows Media Encoder.
Important Although your sound or video file may have the same file extension as one listed below, it may not play correctly if the correct version of the codec (codec: An abbreviation for compressor/decompressor. Software or hardware used to compress and decompress digital media.) is not installed, or if the file is not encoded in a format that is recognized by your version of Microsoft Windows. Encoding is the process of converting data into a stream of ones and zeros. For more information about the most common codecs, including where to get them, see Encoding Audio and Video with Windows Media Codecs or Using codecs.
Audio file formats
File format Extension More information
AIFF Audio file .aiff Audio Interchange File Format This sound format originally was used on Apple and Silicon Graphics (SGI) computers. Waveform files are stored in an 8-bit monaural (mono or one channel) format, which is not compressed and can result in large files.
AU Audio file .au UNIX Audio This file format typically is used to create sound files for UNIX computers or the Web.
MIDI file .mid or .midi Musical Instrument Digital Interface This is a standard format for the interchange of musical information between musical instruments, synthesizers, and computers.
MP3 Audio file .mp3 MPEG Audio Layer 3 This is a sound file that has been compressed by using the MPEG Audio Layer 3 codec (codec: An abbreviation for compressor/decompressor. Software or hardware used to compress and decompress digital media.), which was developed by the Fraunhofer Institute.
Windows Audio file .wav Wave Form This audio file format stores sounds as waveforms. Depending on various factors, one minute of sound can occupy as little as 644 kilobytes or as much as 27 megabytes of storage.
Windows Media Audio file .wma Windows Media Audio This is a sound file that has been compressed by using the Microsoft Windows Media Audio codec (codec: An abbreviation for compressor/decompressor. Software or hardware used to compress and decompress digital media.), a digital audio coding scheme developed by Microsoft that is used to distribute recorded music, usually over the Internet.
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If you need to convert to another format then try WAV there is a very good FREE converter to do this used extensively by forum members who wish to edit their audio tracks.
Audacity
