Two tuning forks of frequencies and are struck together

PHYSICS · Subjective · CBSE · Physics · Waves · Waves

Problem

Two tuning forks of frequencies

256\,\text{Hz}

and

400\,\text{Hz}

are struck together. No waxing and waning of sound is heard. Explain in one or two sentences why beats are not audible, whereas a fork of

256\,\text{Hz}

sounded with another of

260\,\text{Hz}

produces distinct beats.