Voice

What It Covers

Radiolab explores the evolutionary origins of voice from ancient fish 400 million years ago, how mother's voice activates reward centers in children's brains, and disability activist Alice Wong's experience losing her speaking voice after tracheostomy surgery.

Key Questions Answered

• •Evolutionary biology of speech: Human voice evolved from a fish's lung pouch valve 400 million years ago. The vocal cords function as a sphincter muscle that vibrates when air pushes through, not like violin strings. Mammals developed powerful diaphragms and refined vocal folds with cartilage, enabling complex sounds through coordinated movements from gut to tongue tip.
• •Maternal voice neurological impact: Stanford research shows children ages seven to twelve exhibit intense reward center brain activity when hearing their mother's voice, similar to responses triggered by chocolate, music, or drugs. By adolescence (13-16), this effect reverses—unfamiliar voices become more rewarding as teens neurologically shift toward peers for healthy developmental independence.
• •Tracheostomy communication barriers: Patients with tracheostomy tubes lose speaking ability because air escapes through the neck opening instead of passing through vocal cords. Communication boards requiring letter-by-letter eye tracking take extensive time to spell simple words like "baseball," creating profound frustration for people who previously communicated freely through speech.
• •Passy Muir Valve invention: David Muir, a quadriplegic with muscular dystrophy, created a speaking valve at age 25 using duct tape and parts from his ventilator. The one-way valve allows air into lungs but forces exhalation through vocal cords, restoring speech for tracheostomy patients. His father Don built the prototype after David spelled out instructions.
• •Dignity beyond speech capability: Alice Wong challenges the phrase "dignity through speech" used in marketing the Passy Muir Valve, arguing nonspeaking people maintain full dignity through alternative communication methods including sign language, gestures, writing, and technology. She advocates through Communication First organization for recognizing diverse communication modes as equally valid expressions of personhood.