terms: square-law relationship between amplitude (sound pressure variation) and intensity (power level) written in lisp its expressed as:
(setf amplitude-ratio (sqrt power-ratio))

amplitude ratios are expressed in decibels (dB)
dB-ratio = 20 * log base 10(amplitude-ratio)

...so in lisp...try this...
(setf amplitude-of-solo 1.0)
(setf amplitude-of-big-group 20.0)
(* 20.0 (log (sqrt (/ amplitude-of-big-group amplitude-of-solo)) 10.0))
or to find signal to noise (S/N) ratio of 16bits which is the dynamic range on compact discs
(* 20.0 (log (expt 2.0 16.0) 10.0))

lecture topics:
A look at radiation patterns from flutes ...demonstrated with 4 mics in recording studio
Room acoustics and simulation ...demonstrated with artificial reverberation
A look at paths to the listener (hrtf's) ...demonstrated with CLM hrtf example
properties of localization in 3-D
   --ITD-- interaural time delay
   --IAD-- interaural amplitude difference
   --distance cue-- partially depends on ratio of direct / reverb signals
   --filtering-- effect of distance and angle of incidence to the ear

One "3D sound" solution: Putting it all together with convolution.

methods for impulse response measurement
convolution examples in CLM     cnv.ins
rooms and reverberation simulation
multi-channel recording, surround, surround synthesis