Minimum sound energy at high frequency perceived by the ear.

C. E. Jane. Minimum Sound Energy for Audition for Tones of high frequency. Phys. Rev., May 1922.

For frequencies from 2,000 to 14,000 $\dfrac{\text{per}}{\text{sec}}$ it was found that, for the threshold of auditory sensation, an energy of $7{,}10^{-8}\ \dfrac{\text{erg}}{\text{cm}^2\ \text{sec}}$ is required (energy flux in 1 sec through 1 cm²).

This value is practically the same for the whole indicated range of frequencies, although small differences exist not only between different individuals, but also between the two ears of one and the same person.

Above 14,000 $\dfrac{\text{per}}{\text{sec}}$, ever greater amounts of energy are required in order to produce the sensation of sound, and at frequencies from 18,000 to 20,000 $\dfrac{\text{per}}{\text{sec}}$ the energy, 1,400,000 times greater than at low frequencies, gives only the threshold of sensation. This upper limit is higher for children and lower for old people.

28/XII 1922.
S. Rzhevkin.