"Speak up" is the most common advice given to people talking with someone who has hearing loss. It is also the least useful, because volume isn't the only thing that's missing.
The part that carries meaning is the quiet part
Speech has two very different components. Vowels are low-pitched and loud; they carry most of the energy. Consonants — especially s, f, th, sh, and k — are high-pitched and quiet; they carry most of the meaning. Fish, fifth, sit, six, and shift differ almost entirely in their consonants.
High-frequency hearing loss removes exactly those. Raising your voice mostly makes the vowels louder, which were already audible.
Blurring, not just fading
A typical cochlea is a remarkably fine filter bank: it can tell apart sounds that are very close in pitch. Damaged hair cells are broadly tuned, so neighboring pitches blur together. Even when a sound is loud enough to hear, its detail can be gone.
The simulator doesn't model this. It turns each pitch down by the amount on the audiogram, but whatever it lets through keeps the detail of typical hearing, so it can make a loss sound clearer than it really is.
Too quiet, then suddenly too loud
Sensorineural loss also shrinks the range between "just audible" and "uncomfortably loud" — an effect called loudness recruitment. Someone may miss everyday conversation yet flinch when you shout. The simulator doesn't model recruitment; it is worth knowing it exists, because it is the other reason shouting backfires.
What actually helps
- Ask what works for them. People with hearing loss know their own hearing best.
- Face the person, in good light, so they can see your mouth.
- Slow down slightly and rephrase rather than repeat louder.
- Turn down background noise — a quiet room helps more than a loud voice.
- Turn on captions, and be ready to write or text when speech isn't working.
- Hearing aids are not simple volume knobs: they amplify different frequencies by different amounts and compress loud sounds, shaped to the person's audiogram.