;***********************************   BINAURAL LATERIZATION   ************************************
; THE MOST IMPORTANT BENEFIT WE DERIVE FROM BINAURAL HEARING IS THE SENSE OF LOCALIZTION OF THE SOUND
; SOURCE. ALTHOUGH SOME DEGREE OF LOCALIZATION IS POSSIBLE IN MONOAURAL LISTENING, BINAURAL LISTENING 
; GREATLY ENHANCES OUR ABILITY TO SENSE THE DIRECTION OF THE SOUND SOURCE.
; ALTHOUGH LOCALIZATION ALSO INCLUDES UP-DOWN AND FRONT AND BACK DISCRIMINATION, MOST ATTENTION IS FO-=
; CUSED ON SIDE TO SIDE DISCRIMINATION OR "LATERIZATION". WHEN WE LISTEN WITH HEADPHONES , WE LOSE 
; FRONT-BACK INFORMATION, SO THAT LATERIZATION BECOMES EXAGERATED; THE IMAGE OF THE SOUND SOURCE AP-
; PEARS TO SWITCH FROM ONE SIDE OF THE HEAD TO THE OTHER BY MOVING 'THROUGH THE HEAD', OR THE SOUND 
; SOURCE APPERAS TO BE 'IN THE HEAD'.
; LORD RALIEGH (1907) WAS ONE OF THE FIRST TO RECOGNIZE THE IMPORTANCE OF TIME AND INTENSITY CUES AT
; LOW FREQUENCY AND HIGH FREQUENCY, RESPECTIVELY. LOW-FREQUENCY SOUNDS ARE LATERALIZED MAINLY ON THE 
; BASIS OF INTERAURAL TIME DIFFERENCE, WHEREAS HIGH-FREQUENCY SOUNDS ARE LOCALIZED MAINLY ON THE BASIS 
; OF INTERAURAL INTENSITY DIFFERENCES.
; IN THE FIRST EXAMPLE, TONES OF 500HZ AND THEN 2000HZ ARE HEARD WITH ALTERNATING INTERAURAL PHASES OF 
; PLUS AND MINUS 45 DEGREES. AT 500HZ, THE IMAGE SWITCHES FROM SIDE TO SIDE AS THE PHASE CHANGES. AT 
; 2000HZ, ON THE OTHER HAND, NO SUCH MOVEMENT IS PERCEIVED WITHOUT HEADPHONES. (THE INTERAURAL TIME  
; DIFFERENCE VARIES FROM DELTA(T) = DELTA(ALPHA)/2PIF = 250 TO -250 MICROSECONDS IN THE FIRST CASE, BUT ONLY 62.5 TO
; ONLY 62.5 TO -62.5 MICROSECONDS AT 2000HZ).
; IN THE SECOND EXAMPLE, A 2 MILLISECOND PULSE (HEARD AS A "CLICK" IS PRESENTED WITH AN INTERAURAL 
; TIME DIFFERENCE THAT CYCLES, SO THAT THE SOUND SOURCE OF THE CLICK APPEARS TO MOVE BETWEEN LEFT
; AND RIGHT.
; THE THIRD EXAMPLE USES TONES OF 250 AND 4000HZ TO ILLUSTRATE THE EFFECTS OF INTERAURAL INTENSITY 
; DIFFERENCE AT LOW AND HIGH FREQUENCY. THE INTERAURAL INTENSITY CHANGES (IN 1.25S) FROM 32DB TO -32DB.
; IN THE BOTH CASES, THE IMAGE MOVES FROM SIDE TO SIDE. ALTHOUGH THE AUDITORY SYSTEM PROCESSES INTER-
; AURAL INTENSITY CUES AT BOTH LOW AND HIGH FREQUENCY, THE HEAD DOES NOT CAST MUCH OF AN ACOUSTIC
; SHADOW AT LOW FREQUENCY ( DUE TO DIFFRACTION), AND HENCE THERE IS LITTLE INTENSITY DIFFERENCE EVEN
; WHEN THE SOURCE IS LOCATED TO ONE SIDE OF THE HEAD.    
;*****************************************   HEADER   ********************************************           

sr             =         44100
kr             =         4410
ksmps          =         10
nchnls         =         2

 instr         1

 iamp          =         ampdb(p4)                ;P4 = AMPLITUDE IN DB 
 ifreq         =         p5                       ;P5 = FREQUENCY
 ifunc         =         p7                       ;P6 = PANNING FUNCTION FOR SIGNAL
 idur          =         p3                       ;P7 = FUNCTION

 k1            linen     iamp,0,p3,0         
 a1            oscili    k1,ifreq,ifunc        
 k2            oscili    1,p3,p6
 kleft         =         sqrt (k2)
 kright        =         sqrt (1-k2)
 aleft         =         a1 * kleft
 aright        =         a1 * kright
               outs      aleft,aright 
 endin  

 instr         2

 iamp          =         ampdb(p4)                ;P4 = AMPLITUDE IN DB 
 ifreq         =         p5                       ;P5 = FREQUENCY
 ifunc         =         p7                       ;P6 = PANNING FUNCTION FOR SIGNAL
 idur          =         p3                       ;P7 = FUNCTION
 
 k1            linen     iamp,.02,p3,.02
 a1            oscili    k1,ifreq,ifunc        
 k2            oscili    1,p3,p6
 kleft         =         sqrt (k2)
 kright        =         sqrt (1-k2)
 aleft         =         a1 * kleft
 aright        =         a1 * kright
               outs      aleft,aright 
 endin  

 instr         3

 iamp          =         ampdb(p4)                ;P4 = AMPLITUDE IN DB 
 ifreq         =         p5                       ;P5 = FREQUENCY
 ifunc         =         p7                       ;P6 = PANNING FUNCTION FOR SIGNAL
 idur          =         p3                       ;P7 = FUNCTION
 
 k1            linen     iamp,.02,p3,.02
 a1            oscili    k1,ifreq,ifunc        
 k2            oscili    1,p3,p6
 kleft         =         sqrt (k2)
 kright        =         sqrt (1-k2)
 aleft         =         a1 * kleft
 aright        =         a1 * kright
               outs      aleft,aright 
 endin  
              
 instr         4

 iamp          =         ampdb(p4)                ;P4 = AMPLITUDE IN DB  
 ifreq         =         p5                       ;P5 = FREQUENCY
 ifunc         =         p7                       ;P6 = PANNING FUNCTION FOR SIGNAL
 idur          =         p3                       ;P7 = FUNCTION
 
 k1            expseg    (iamp/2.8125),idur/10,iamp,idur/10,(iamp/2.81285),idur/10,iamp,idur/10,(iamp/2.8125),idur/10,iamp,idur/10,(iamp/2.8125),idur/10,iamp,idur/10,(iamp/2.8125),idur/10,iamp,idur/10,(iamp/2.8125)
 a1            oscili    k1,ifreq,ifunc        
 k2            oscili    1,p3,p6
 kleft         =         sqrt (k2)
 kright        =         sqrt (1-k2)
 aleft         =         a1 * kleft
 aright        =         a1 * kright
               outs      aleft,aright 
 endin  
 instr         5

 iamp          =         ampdb(p4)                ;P4 = AMPLITUDE IN DB  
 ifreq         =         p5                       ;P5 = FREQUENCY
 ifunc         =         p7                       ;P6 = PANNING FUNCTION FOR SIGNAL
 idur          =         p3                       ;P7 = FUNCTION
 
 k1            expseg    iamp,idur/10,(iamp/2.81285),idur/10,iamp,idur/10,(iamp/2.81285),idur/10,iamp,idur/10,(iamp/2.81285),idur/10,iamp,idur/10,(iamp/2.81285),idur/10,iamp,idur/10,(iamp/2.81285),idur/10,iamp
 a1            oscili    k1,ifreq,ifunc        
 k2            oscili    1,p3,p6
 kleft         =         sqrt (k2)
 kright        =         sqrt (1-k2)
 aleft         =         a1 * kleft
 aright        =         a1 * kright
               outs      aleft,aright 
 endin