Assume that you play an A-LAW compressed .wav file in Windows Media Player on a computer that is running Windows 8. When you change the playback speed by using the speed control, the pitch of the audio file is not maintained.


  • This issue does not occur when you play a U-LAW compressed .wav file.

  • This issue may also occur when you play the file by using other applications or voice messaging systems.


Update information

To resolve this issue, install update rollup 2855336. For more information about how to obtain this update rollup package, click the following article number to view the article in the Microsoft Knowledge Base:

2855336 Windows RT, Windows 8, and Windows Server 2012 update rollup: July 2013


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

More Information


A-LAW and U-LAW are companding algorithms. The algorithms are primarily used by digital telecommunication carriers to reduce the bandwidth that is needed to carry sound. Additionally, the algorithms are used independently of any other compression algorithm that is used to store sound files on computers. The A-LAW algorithm is used by European digital communication providers and for international communications, and the U-LAW algorithm is used by North American and Japanese providers.

For more information about A-LAW and U-LAW algorithms, go to the following websites:

General information about A-law algorithm

General information about μ-law algorithm

Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.

For more information about software update terminology, click the following article number to go to the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

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