I have a tuning fork and a tuning app on my tablet. I am interested to know which to trust.
The tuning fork is old. It was my father's (for his violin) and hence is probably from the 1930s at the latest (maybe older if it was second hand or from his father).
The tablet is a Samsung Galaxy Tab 5 and runs Android. The app is called DaTuner Lite.
The app says that the tuning fork is 438.2Hz. So, I am wondering which is more likely to be right. Is the tuning fork slightly flat or the app underreading slightly?
An alternative phrasing of the question is how accurate are these cheap or free apps?
Obviously, this small error is not important, I am just curious.
On one side it says: "British Standard A".
On the other it says: "England John Walker".
There's no indication of the frequency that it claims to be.
I just realised that I can perform another test. Some years ago, I wrote a Java program which generated a series of WAV files containing pure sine waves at various frequencies. These include A4 at 440Hz. I just played that and the tablet reported it as 440.2Hz. So, closer than the tuning fork. I think that I can now conclude that the tuning fork is probably not 440Hz, maybe it is intended to be 438Hz as mentioned by Bob. The .2Hz difference is interesting. I need to review my code. It seems that either I, or the author of the app, has a rounding error. If we assume that the tuning fork is exactly 438Hz then it is curious that the app overreads it and my test tone by the same .2Hz.
And another test.
I found a recording of an orchestra tuning up. It was the Liceu Barcelona. It was hard to get a clear reading from the app as there was lots of other noise but at one point, it seemed to catch the oboe; it read 443Hz (with some fluctuation of about .2 or .3 above). So, another confusing data point.
And even more data.
I installed another tuning app on the same tablet. It reports my test tone as 440.3Hz. So, even if my test source is wrong, it suggests some level of error in these apps as one consistently reports 440.2Hz and the other 440.3Hz. Of course, the true value may be close to midway between the two. I also installed the first app on a different device, Samsung again but a phone rather than a tablet, it also reported 440.2Hz.