How to compare envelopes between different signals (or other ideas to help me compare signals)

I am doing a project where I am trying to characterize specific acoustic signals that come from different material interactions. For example, I am rubbing two metal components together while recording acoustic waves and then rubbing one of the metal components against a plastic component. Each set of data recording which represents like a 30 second test results in hundreds of different waveforms.

I have written a script that goes through every waveform and calculates several parameters (for example, average frequency, peak amplitude, and the # of times the signal crosses a certain dB threshold) for each waveform. It then averages these values for the entire test and outputs the data to a spreadsheet. So for example, the first row will have the average and standard deviation of the previous parameters for the 180 waveforms that came from the metal-metal interaction test, and the second row has the average/standard deviation of the parameters for the 230 waveforms that came from the metal-plastic interaction.

The problem with this is that many of the waveforms are noisy outliers that disproportionately affect the averages, but I can't think of an easy way to determine whether or not a specific signal should be eliminated as noise or not.

When I visually look at all the waveforms for each material interaction, I notice that there are a few waves that repeat throughout the test. The quantitative values of the parameters might not match exactly, but the shape of the signal is so unique and repeatable. I feel like these are the signals of most interest to my project.

In my mind, I feel like the best way to analyze my data would be to create envelopes for each signal, and then if a particular envelope shape is repeated throughout the test, I know to categorize it as a characteristic signal and I can then analyze the parameters (frequency, etc.) only for those signals.

I'm still relatively new to MATLAB and signal analysis, so I don't know how to make an envelope for a signal but I do know it's possible and I should be able to figure it out relatively easy. That's not my issue. My main concern is finding a way to compare different signal envelopes. I almost feel like the best way to do this would be to create images of the envelope and then using some sort of image processing technique to visually compare the shape of the envelopes.

Thank you for any advice/suggestions that might expedite a solution to this signal comparison problem I'm having.