Why does input and sound is broken at specified point? ...Becauase Sound CPU is reset.

Resetting Sound CPU is triggerd in the above routine which is executed when boss tank appears.

2ED1: 34            inc  (hl)
2ED2: CD 87 33      call $3387
2ED5: 3A 3D C0      ld   a,($C03D)
2ED8: DA CF 04      jp   c,$04CF
2EDB: 11 47 00      ld   de,$0047
2EDE: 21 98 C1      ld   hl,$C198
2EE1: 19            add  hl,de		// hl = $C1DF
2EE2: 7E            ld   a,(hl)
2EE3: B7            or   a
2EE4: CA EB 2E      jp   z,$2EEB
// Sound CPU Reset!
2EE7: D3 00         out  ($00),a
2EE9: D3 01         out  ($01),a

2EEB: ...

The value on $C1DF must be always 0.
But if it's not 0, main CPU calls to reset sound CPU.

Where does $C1DF is set? ...It's in the following routine on main CPU.

0E54: 3A E7 C1      ld   a,($C1E7)
0E57: 2A E5 C1      ld   hl,($C1E5)
0E5A: 95            sub  l
0E5B: 86            add  a,(hl)
0E5C: 32 E7 C1      ld   ($C1E7),a
0E5F: 23            inc  hl
0E60: 22 E5 C1      ld   ($C1E5),hl
0E63: 01 01 40      ld   bc,$4001
0E66: 09            add  hl,bc
0E67: D0            ret  nc
0E68: 22 E5 C1      ld   ($C1E5),hl
0E6B: 7D            ld   a,l
0E6C: 21 E7 C1      ld   hl,$C1E7
0E6F: AE            xor  (hl)
0E70: 77            ld   (hl),a
0E71: C8            ret  z
// Write 0x37 into $C1DF
0E72: 21 A8 C1      ld   hl,$C1A8
0E75: 06 00         ld   b,$00
0E77: 0E 37         ld   c,$37
0E79: 09            add  hl,bc
0E7A: 71            ld   (hl),c
0E7B: C9            ret

This routine is... In-game ROM checker!!
$C1E5 (2 bytes) is current address on ROM and $C1E7 is calculated value.
This routine starts after player helicopter takes off and finish checking after read $BFFF (0xBFFF + 0x4001 = 0),
it's around first part of Area 4.
And if total calculated value is not 0, stored 0x37 into $C1A8 as ROM error.

I attach 4 state save files for tigerh which are saved on 0.128u4.

And I have confirmed these routine on tigerhj, tigerhb1, tigerhb3.

In tigerhb2...

2EDB: 11 47 00      ld   de,$0047
2EDE: 21 98 C1      ld   hl,$C198
2EE1: 19            add  hl,de
2EE2: 7E            ld   a,(hl)
2EE3: B7            or   a
2EE4: CA EB 2E      jp   z,$2EEB
2EE7: AF            xor  a

2EE8: 00            nop
2EE9: 00            nop
2EEA: 00            nop

2EEB: ...

Resetting sound CPU is killed so that this problem never happens.