Cepstral Peak Prominence (CPP)
Cepstral peak prominence (CPP) is one of the most robust acoustic measures of voice quality currently available and is super easy to measure clinically. CPP can be measured using several commercially available software programs, however for this tutorial, we will be using the Praat freeware - so go head and and download now if you haven't already.
First, using Praat, select the audio sample of interest, such as sustained /a/ or the Rainbow Passage. The the CAPE-V sentence “we were away a year ago” is shorter, and research suggests can be used in place of the Rainbow Passage. Then select “Analyse periodicity – ”, then select “To Power Cepstrogram”, then select > “OK”
Second, select the new file that begins with “PowerCeptrogram”, then select “Query – ” > “Get CPPS…”,
Lastly, change the default settings in the "Time averaging window (s):" from 0.02 to 0.01, and in the "Quefrency averaging window (s):" from 0.0005 to 0.001
Before
After
And just like that, you have powerful new objective acoustic measure to add to your voice and/or motor speech evaluation and an invaluable quantitative treatment outcome! Check out the this article for normative data, the below references for more detailed information, and the below video tutorial.
References:
Murton, O., Hillman, R., & Mehta, D. (2020). Cepstral peak prominence values for clinical voice evaluation. American Journal of Speech-Language Pathology, 29(3), 1596-1607.
Maryn, Y., & Weenink, D. (2015). Objective dysphonia measures in the program Praat: smoothed cepstral peak prominence and acoustic voice quality index. Journal of Voice, 29(1), 35-43.
Watts, C. R., Awan, S. N., & Maryn, Y. (2017). A comparison of cepstral peak prominence measures from two acoustic analysis programs. Journal of Voice, 31(3), 387-e1.
Sauder, C., Bretl, M., & Eadie, T. (2017). Predicting voice disorder status from smoothed measures of cepstral peak prominence using Praat and Analysis of Dysphonia in Speech and Voice (ADSV). Journal of Voice, 31(5), 557-566