Pitch is the source
Fundamental frequency is measured in Hz. Faster vocal-fold vibration produces a higher perceived pitch; slower vibration produces a lower pitch.
Resonance is the filter
The throat, mouth and nasal cavities emphasize different frequency bands called formants. Their shape and effective length influence whether a voice sounds bright, dark, large or small.
Use both concepts
Recordings with similar F0 can sound different because resonance, loudness and articulation also matter. A pitch test describes one acoustic feature; it is not an overall voice rating.
Hear the difference without forcing it
Say the same short sentence comfortably, then repeat it with slightly different vowel shapes. Listen for a change in brightness while observing whether Hz stays similar. This is a listening comparison, not a treatment or a promise of permanent change.
What this test cannot separate
The analyzer estimates F0; it does not measure formants or score resonance. A similar median with a different sound is therefore possible. For a detailed acoustic comparison, inspect a recorded spectrogram with an appropriate analysis tool such as Praat.
Sources and further reading
Sources checked: