Implement jitter and shimmer

[clarkenj]

Timing and amplitude fluctuations of glottal pulses (jitter and shimmer, respectively) - Wiesman et al. (2023)

There does not appear to be a "simple" way in parselmouth, but I have found the following:

• Python implementation, although fairly old. Also an OSF repo
• Some tips from the parselmouth developer

References (AD/MCI):

• Mirheidari et al. (2019)
• Yancheva et al. (2015)
• López-de-Ipiña et al. (2013)
• Pulido et al. (2020) (review)
• Meilán et al. (2014): shimmer important for classification
• Hasan & Krishnan. (2022): jitter most important feature for classifying AD versus control. Shimmer also important

See also Jitter Estimation Algorithms for Detection of Pathological Voices

[cbedetti]

I implemented the scripts here: ad03f9a

I'm a bit worried about this comment in the notebook for the pitch measures.

This is the function to measure source acoustics using default male parameters.

[clarkenj]

Good spot, I hadn't come across that, it is worrying.. It looks like we might have to have different parameters for male and female voices (did you see this issue?)

[cbedetti]

Great, I implemented it in c2a1d0e

For now, I'm not closing any issues as this will be information to be included in the documentation.