Why there is no universal cutoff
This site cannot supply a validated Hz boundary for a deep voice. Any descriptive bands in the tool are editorial labels, not clinical categories or a population percentile.
A lower speaking median means slower estimated vocal-fold vibration in that sample. It does not, by itself, establish greater depth, better health or a more desirable voice.
Is 85 or 95 Hz deep?
An 85 or 95 Hz result needs the same checks as any other result: natural speech, enough voiced frames and repeatable conditions. The lowest brief sound is not habitual speaking pitch.
Why resonance matters
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.
Separate a low note from a speaking voice
Read a paragraph naturally, then compare its median with a deliberately low sustained vowel. These are different tasks. Use the reading result for everyday speech comparisons; do not combine both samples into one personal range.
Interpret apparent sudden drops
If a new result is roughly half the usual value, repeat in a quiet room and listen for creaky or interrupted speech. Pitch trackers can select a subharmonic. A lower number is not proof of training progress.
Sources and further reading
Sources checked: