AAC quantization

Hi..
I am new to the field of audio compression. Could someone explain the
quantization process?.

I see that the spectral value is multiplied
by the following to get the quantized value

(pow(2, (3/16)*scale_factor))*(spectral_value^0.75)

According to my understanding, power-law quantization should be as
follows,

pow_value = spectral_value^0.75;
pow_sc    = scale_factor^0.75;

quant_value = pow_value/pow_sc;

Could someone explain the logic behind the formula used in AAC
quantization?