The mid-frequency hearing advantage explains why alarms and speech amplification target 1000-6000 Hz.

Evidence

These measurements have strong implications for our auditory perception. First, consider the implications for superior audibility in mid frequencies versus low and high frequencies. Sounds in this frequency range are more easily detected than other sounds, and therefore are used in sirens and alarms. These frequencies, notably, also contribute substantially to speech understanding, and therefore are the most important to amplify for listeners with sensorineural hearing loss. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 252

Categorization

• XREF: Central to the reader’s audiology applications goal: why amplification for sensorineural loss targets mid frequencies.