I have used an app to measure shutter speed through sound, with my iPad. The trick is in learning to analyze the sonogram to determine which spikes represent the opening and closing of the shutter. I found that leaf shutters were a lot easier to interpret than an SLR, where the mirror sound can be confused with the shutter, and where focal plane shutters may make more than one noise as they fire. This sonogram is relatively easy to interpret at the slower shutter speeds, and at slower speeds the opening and shutting of the shutter provide a good measure of how much light is getting through. At the fastest speeds the sonogram can be harder to read, and the time from "snick" to "snack" may not be a precise measure of the amount of light getting through either, since the shutter mechanism travel is a factor as well (both leaf shutters and the way focal plane curtains interact can make this calculation less straightforward than a simple unit of time. Now I have an electronic device that measures the shutter speed by shining a beam of light through the camera body to a receptor on the lens side This is precise at all shutter speeds. The shutter speed-measuring app is worth a try. It should give you a good idea of the speed of your most important mid-range and slower speeds, and as long as you know what the speeds are, and have a way to set the shutter manually, you are good to go. The good news is that print film is very forgiving, even if the shutter is off, you will get good results, and by learning from your results you can adjust exposure to where you want it by experience.