From Dr Geoff Lindsey.

What makes you sound young or old, big or small? See Marques Brownlee’s voice transform from teen to adult — and find out what it tells us about the science of voice change.
👉 Support my work on Patreon: https://www.patreon.com/c/drgeofflindsey
Join the discussion on Discord: https://discord.gg/4ANd8rtj

Ever wondered how a teenager’s voice turns into an adult’s? In this video I show how changing pitch and resonance — the “source” and “filter” of speech — can make the same voice sound young or mature, large or small. Along the way, we’ll hear how YouTuber Marques Brownlee’s teenage voice became his adult voice, and I’ll use Praat to demonstrate pitch, formants, and the source–filter model of speech production. Voice breaking in adolescence is just one example of how vocal folds and vocal tracts develop at different rates, and by analysing Marques’s archive of videos I show how those changes shape the voices we all grow into.

▶ More in the playlist [The Science of Voices](https://www.youtube.com/playlist?list=PLZEIORpJuQYwKQgRXoet2YutfheHRHDw-)
▶ Also see [Analysing Famous People’s Speech](https://www.youtube.com/playlist?list=PLZEIORpJuQYxQUGl08HqayXipPOirkx1O)

⏱️ Timestamps:
0:00 Intro & Marques
0:33 Quiz
1:21 Source–filter model
3:00 Richard Kiel & Kenny Baker
6:22 Marques’s voice over time
9:35 Praat demo: pitch & formants
10:46 Outro

📌 References:
Praat software (free download): https://www.fon.hum.uva.nl/praat/
Photo of Gunnar Fant: CC BY-SA 3.0 https://commons.wikimedia.org/wiki/File:Gunnar_Fant.jpg
All other clips/images used under fair use for educational purposes.

This video covers: Marques Brownlee voice change, how male voices change at puberty, pitch vs formants, the source–filter model/theory, and demonstrations in Praat. If you’re interested in phonetics, linguistics or how accents and voices develop, you’re in the right place.