I have had more than one occasion to be working on repair, cal of various pieces of equipment and needed to do adjustments in awkward places but have to look at DMMs or meters while looking at adjustment point. Ugh. If you take an Arduino board, connect it to PC, you can create the basic interface to make talking instrumentation. And code in blocks, rather than C. Here is a simple talking voltmeter done with Snap4Arduino ( IDE, free). Adding freq or period or T or whatever should not be too difficult. Freq and Period, there is not a program block in Snap4Arduino for that, I think using a PSOC to do general DAQ like functions, then pass that to Arduino would give one a very flexible foundation. PSOC to Arduino using I2C interface. https://forum.allaboutcircuits.com/threads/talking-arduino.161537/ This example basically uses Arduino to measure the V, then passes that to Windows and the value is converted to speech and spoken by PC. This sample is just a simple first proof of concept. A NANO board or UNO board ($ 4 or $6) great starting point. Just thinking should not be too difficult to use in blind user applications as well. Like readout freq, but I think one would have to do some C coding as well for that. Regards, Dana.