Your body changes
Hydration, sleep, fatigue and temporary vocal-fold swelling influence vibration. Morning voices can behave differently from voices measured after hours of speaking.
Context changes speech
People often raise pitch when excited, speaking loudly or addressing unfamiliar listeners. Sentence melody and language can also move the median.
- Emotion and stress
- Speaking volume
- Posture and breath support
- The words or passage used
Build a useful baseline
Measure at a similar time, in the same room, with the same passage. Track a weekly median instead of reacting to every individual reading.