How to get the exact amplitude of a point in the waveform

I am currently working on a Science Fair Project in which I have to study and compare the amplitudes of sound waves produced by new and deteriorated guitar strings. I am using audcity to record the sound of each string as it is individually plucked. I am having problems in finding a way to get the exact amplitude of a point in the waveform of the recording at a given time. Thee scale that is found at the left before each audio file dos not provide exact numbers, so I would have to estimate the amplitude, which is something I cannot do for this project.
What steps can I take to find this information within Audacity?
This is somewhat urgent.

You can try Analyze > Sample Data Export….


How are you controlling for plucking energy? If I pluck a string harder it’s going to get louder no matter how old it is.

A quick-and-dirty way to find the peak is to select/highlight the part of the waveform you’re interested in, and then Effect → Amplify.

Amplify will default to the amount of gain needed to hit 0dB.
In other words if amplify defaults to 4dB, the current peak is -4dB.

Then of course, cancel the effect instead of applying the gain change.

(If both waveforms are have 0dB peaks, they are both clipped and reading the peaks won’t tell you which is “louder”.)

Old and new strings sounding different would be the project. "Note the overtones of the old string have shifted down slightly and the harmonics around 3,000 Hz are less leading to a mellower sound.