If you are interested in building your own signal processing tools for sound engineers, then you will need to be familiar with a number of different technologies. Some of the technologies that you will need to know include:

1. Csound - Csound is a software suite that allows sound engineers to create and evaluate sound models. It is widely used in the sound industry and can be used to create a wide variety of signal processing tools.

2. MATLAB - MATLAB is a powerful data analysis and visualization tool that is often used by sound engineers to perform mathematical operations on sound data. It can also be used for signal processing.

3. Signal Processing Toolbox for Windows - The Signal Processing Toolbox for Windows is a free software library that contains a variety of signal processing toolsets that can be used by sound engineers.

4. GNU Octave - GNU Octave is a free software platform that can be used for signal processing, mathematics, and data analysis. It is widely used in the scientific community and can be very useful when working with sound data.