One reason that the task of inventing manners is so difficult is that etiquette is folk custom, and people have emotional ties to the forms of their … - Judith Martin

DEAR MISS MANNERS:
When does a gentleman offer his arm to a lady as they are walking down the street together?

GENTLE READER:
Strictly speaking, only when he can be practical assisstance to her. That is, when the way is steep, dark, crowded, or puddle-y. However, it is rather a cozy juxtapostion, less comprising than walking hand in hand, and rather enjoyable for people who are fond of each other, so Miss Manners allows some leeway in interpreting what is of practical assisstance. One wouldn't want a lady to feel unloved walking down the street, any more than one would want her to fall of the curb.

The polite thing would be to say to the noisy person, “I beg your pardon, but I can’t hear the music. I wonder if you would mind talking more softly?” By the time you have said all this, a third party will utter a loud shush, thereby accomplishing your purpose without sacrificing your manners.

There is no quick and easy way to rear a child. It takes eighteen years of constant work to get one into presentable enough shape so that a college will take him or her off your hands for the winter season, and it can easily take the child on permanently.