Simple Feedback Trainer

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SFT (Simple Feedback Trainer) is an application designed to simulate the process of 'ringing out' a sound system and train the user to recognise frequencies by ear. It was designed after a discussion about the topic on

To date (Oct 2009) there have been over 35,000 downloads of SFT.



SFT is released under the terms of the Common Development and Distribution License, Version 1.0. Developers are encouraged to review and improve the software and submit patches, and the project is actively looking for volunteers to join the development team.


Thanks to the readers of and the LAB for comments and support, and to David J Taylor who wrote the original code used in the tone generator. Thanks also to ajv for early testing.

© Ian Gregory