Part of the challenge that Lanthimos presents in Alps is that the individual differentiation that members of the group undergo is both significant and simultaneously insignificant.  Members of the program seek to be stand- ins for those who have passed, signing a pledge of that which they can and cannot do.  When they become integrated into these settings, they try to emulate the actions of the deceased.  

At times, this can be seen in voice modulations.  The nurse, for example, wants to be accepted into the family whose daughter has died.  Yet, she is shown to not be in control of how that integration takes place.  The family, also, is not entirely certain of what direction to give her.  It's an odd dynamic because she wishes to change who she is, and the family wishes her to be a stand- in for the daughter.  Yet, neither one really knows how to navigate the dynamic.  No one is in the position of clear authority to indicate what she is to do, such as how should her voice change. The result is that the nurse's voice inflects yearning for acceptance.  This modulation is unclear, for it might reflect her desire to be accepted, something that Lanthimos himself points to as part of her characterization:

Her [The Nurse's] life is empty. She doesn’t feel comfortable in her life. Compared to that, even an abusive lover or family could be better... It’s not specifically the family home that appeals to her. What matters is that she’s trying to belong in a different life, whatever that may be, to find something to make her own, to be part of a certain kind of relationship.

Lanthimos's quote reminds us that the voice changes that Alps members undergo are both significant and insignificant.  We can hear deliberate voice changes, but it is unclear if they are operating as themselves seeking something else or as the stand- in.  The voice changes shows a changing role, but we are uncertain as to what that role is.  As in the case of the Nurse, the role change might be more reflective of a personal need.  The idea of the Alps, as a name, was meant to capture the essence of both the specific and general.  This was the belief of how the group was to function.  Lanthimos' fundamental point is that human consciousness is challenging to understand. Roles do change, yet their meaning is unclear.  Voices do change, yet their meaning is unclear. 

This challenging condition means that any modulation in voice is not one that represents an element of control.  When characters' voices change in their role, it can be reflective of a desire to move into character.  Yet, it might also be a desire for members to find a new character, "to find something to make" as their own. Lanthimos suggests that in this light, the change in voices can reflect new roles that are being played both internally and externally.  No one is entirely certain of what the voice change means and this lack of totality becomes one of the film's central ideas. Human consciousness is a puzzle, something that substantiates the need for the Alps program. Yet, it also brings confusion within it.  When the voices change in the characters, the shift is not absolute and it is not lucid. We know that there is a change, but we do not know if the change is meant to merge with the role being played or if it is something subjective.  Like life and death itself, only questions remain.