

One interpretation I've heard of this verse is that it refers to the sin 
of physically abusing one's wife.  The husband is usually physically 
stronger than his wife but is not permitted to use this to dominate her.  
He must honor her as his sister in Christ.  This would therefore be an 
example of a specific sin that blocks prayer.

This verse also makes me think of the kind of husband who decides what 
is God's will for his family without consulting his wife.  God reveals 
His will to both the husband and the wife.  There needs to be some 
degree of mutuality in decision making.  Even those whose understanding 
of the Bible leads to a belief in an authoritarian headship of the 
husband need to incorporate this in order to have a functional family.  
One way to look at it is that God speaks to the wife through the husband 
and to the husband through the wife.
