CNAQ: a MATLAB acquisition tool for computing transfer functions over audio cards

Since transfer function measurements require very precise buffer management, it is not easy to find any free and/or educational software which processes them with consumer audio cards, cheaper than professional ones but useful. Some people often use musical sequencers to generate and acquire signals but data can't be easily analyzed in other specific engineering codes because the lengths of the samples can't be easily fixed for example. Therefore, we decided to develop a specific software for general audio acoustic measurements with these main constraints: choose a programming language compatible with existing educational and professional tools, promote multi-platform interpreted languages, be able to use consumer audio cards, publish the source code under the terms of a free software license. CNAQ provides a graphical interface under MATLAB to process sweep sine measurements for any kind of acoustical or electronic application in the audio range. The current features of the software and some development ideas, such as implementing convolution based Farina's method, will be also presented.