On Tuesday, December 22, 2015 at 12:53:50 PM UTC-5, amdx wrote:
To do that you need to know the shape of a sine wave... perfectly.
You could use a dual trace and compare a sine wave to your trumpet note.

Or use your computer sound card and see what you really have.

Yes, in 2015 I can do this, and have.

My suspicion was that it was not really possible in 1956 to have done what he claimed to have done. I figured in the time domain the most you would see is a tiny ripple on a scope trace, maybe not detectable. But I asked the question here because you all actually know how to use scopes (and some of you may be old enough to remember 1950s scopes).