Hi there, I assume that the context for this dialogue is that the woman is complaining about something that other people present ('them') have done or failed to do? If so, then; 'wouldn't want' indicates that the speaker is referring to the possible future consequences (of speaking with a loud voice) 'don't want' indicates that the speaker is referring to the definite present consequences (of speaking with a loud voice) Note also that this structure is used for irony. So the woman may be contradicting the man, not agreeing with him. Hope that helps, Helen

it softens it.

@necip You're right, I figured it out from the context. But, why didn't she use "don't" instead of "wouldn't"?

İt means like "dont" in this context