Isaac shouts, damaging and pushing away nearby enemies.
The item can be used when not fully charged, but deals more damage and has increased range the more charges it has when used.
The damage the shout deals is 20 + 28 per charge used.
The shout also deals extra ticks of damage to enemies that are close enough. These extra ticks deal damage equal to 2.5 + 3.5 per charge used, and can tick a number of times up to half the charges used (rounding up).
The range of the extra ticks also varies depending on the charges used: enemies that are closer to Isaac will receive more ticks of damage.
Larynx gains 1 charge whenever Isaac takes damage, as well as through normal means.
The Battery: Larynx can hold up to two full charges. Only up to 12 charges will be used at a time.
Habit: Both on-hit charge effects stack, charging 2 points per hit.
Hairpin: Fully recharges Larynx at the beginning of boss fights, giving Isaac a way to easily devastate several bosses.
Book of Virtues: Spawn red wisps on the middle ring. The wisps deals contact damage equal to 30% of Isaac's damage * Charges Used. Charges Used equals the number of charges Larynx had at the time it was used. Health = 1 * Charges Used. Tear Damage = 1.5 * Charges Used.
Void: Very poor combination. Absorbing Larynx and using it through Void will cause Isaac to only perform the 1-charge version regardless of how many times he has taken damage or how many charges Void has, resulting in minimal damage.
Larynx is the medical term for the voice box, the organ that holds the vocal cords in mammals.