If an infant can scream at a sound level of 96.0-dB measured at a distance 11.0-cm from their mouth, how far away should a parent stand so that the

If an infant can scream at a sound level of 96.0-dB measured at a distance 11.0-cm from their mouth, how far away should a parent stand so that the child can be seen but not heard? (The threshold of hearing is 0-dB, or equivalentlyI0= 10-12-Wm-2.) Assume spherical symmetry for the dispersion of the sound wave energy (this is of course a bad assumption).

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