What happened to Plant's voice in 1972 ? in Led Zep Live Posted April 4, 2019 18 hours ago, NealR2000 said: The male voice not only gets deeper during adolescence where there's a rapid change, but it also tends to deepen very gradually throughout life. I'm no expert on why this second phase of voice deepening occurs, but I suspect it's due to wear and tear of ones vocal chords. Now add to that, the life of a professional singer, and add further to that, a professional singer like Plant, who in his younger years, really sang his lungs out. I still think Robert had a strong vocals, I listened to NYC 1977 and he still had it, just wish they did custard pie live !