DEAR ABBY: Hooray for Cora Laird of Iowa who complained about how difficult it is to hear the dialogue over the noisy background sounds that many television shows feel are necessary. To her list, may I add: waterfalls, street traffic, but mostly -- background music. (In some cases I have concluded the dialogue is secondary to the music, since there is no way I can hear what is being said!) I also wear a hearing aid.

Your suggestion to write to the various sponsors was a bit impractical, since in a two-hour show there are approximately seven breaks with eight or nine commercials, plus TV ads in each one. Besides, the commercials are not the main problem -- I just hit the mute button; it's trying to hear the show itself.

The only way to reach the "powers that be" is through your column. A letter would not carry the clout your column does. If they would put filters in their ears, they might find out how truly irritating these background sounds are.

Have others written to substantiate this ongoing problem? -- HAD IT WITH BACKGROUND IN THOUSAND PALMS, CALIF.

DEAR HAD IT: I have received hundreds of letters with the same complaint -- however, one contained the following good news. Read on:

DEAR ABBY: There are about 20 million people in the United States with some degree of hearing loss -- also millions of recent immigrants still struggling to learn English. In addition, there are millions of adults who are learning disabled, or simply never learned to read.

What do they all have in common? They can all benefit from closed-captioned television. The problem: Very few of them realize they can be helped by closed-captions, let alone own the caption decoder needed to decode the otherwise invisible subtitle-like captions that are broadcast with many television shows, and recorded with many home rental video movies. (Contrary to popular belief, closed-captions are not just for deaf and hard-of-hearing people.)

The good news: Many people who become deaf early in life own a caption decoder. The National Captioning Institute claims that half the caption decoders sold were sold to Hispanic and Asian Americans who find it easier to understand new idioms and strange English expressions when they can read and hear the words at the same time.

The bad news: People who lose their hearing late in life either don't know about closed-captions, or consider "dependency" on captions as a sign of aging.

More good news: Starting July 1, 1993, ALL television sets 13 inches or larger made or sold in the United States will have a closed-caption decoder built inside!

Abby, please educate your readers and encourage them to turn on the decoder at all times if they have children at home who are reading at or below fourth-grade level. That little decoder chip inside the television set may help put a permanent dent in the illiteracy rates of this country. -- ANDREA SHETTLE, GALLAUDET COLLEGE, WASHINGTON, D.C.

DEAR ANDREA: Thank you for your informative letter. I am sure many will be very interested in the information you have to share.

AND DEAR READERS: Anyone interested in learning more about closed-caption technology may contact: National Captioning Institute Inc., 5203 Leesburg Pike, 15th Floor, Falls Church, Va. 22041. NCI has two toll-free numbers: (800) 533-9673 for hearing people, and (800) 321-8337 for deaf and speech-impaired people.

To get Abby's booklet "How to Write Letters for All Occasions," send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Letter Booklet, P.O. Box 447, Mount Morris, Ill. 61054. (Postage is included.)

DEAR READERS: It's autumn again -- and Halloween will soon be here. That means it's time to remind readers with small children that:

-- Somebody's child will be seriously injured or killed in a Halloween-related traffic accident.

-- Somebody's child will be badly maimed or fatally burned due to a flammable costume.

-- Somebody's child will be coaxed into an automobile or lured into a secluded area and sexually assaulted.

To make sure that that child isn't yours, I offer these tips to preserve the safety of your children:

-- Use flameproof costumes only. If costumes are made at home, treat the fabric with a flame-resistant solution.

-- Because masks, floppy hats, wigs and veils often interfere with a child's vision, use makeup instead.

-- Accessories such as swords, broomsticks, hatchets, wands, etc., should be made of cardboard rather than plastic, metal or wood. Sharp items are dangerous!

-- Provide youngsters with flashlights to prevent falls on sidewalks or porch steps. (Positively no lighted candles should be carried!)

-- Decorate your child's costume and trick-or-treat bag with reflective tape to make them highly visible to motorists.

-- Remind children that they should never enter the home of a stranger or accept rides.

-- Adults can help by keeping their yards well-lighted.

-- Parents should check all "treats" before allowing children to eat them.

-- Very young children should never be out after dark unless accompanied by an adult.

So, let's make it a safe Halloween for all children, and come Thanksgiving, we will have more to be thankful for.

DEAR ABBY: Like many others, I can't say I've read your column for years because I'm only 11 years old. But I have read it a great many times.

I have a very bad habit. I suck my thumb and bite my nails. In fact, I've bitten one of my nails so low it started to bleed without my knowing it. It doesn't even hurt. I started sucking my thumb when I was about 3 years old; then I started biting my nails when I was about 6.

Whenever I catch myself, I take my hands away, or try to "hurt" my hand. Usually my family catches me when I'm not aware of what I'm doing. Abby, please help me, and sign this ... THUMB IN MOUTH AND NO NAILS

DEAR THUMB: Try this. Put a rubber band on your wrist, and when you get the urge to suck your thumb or bite your nails, snap the rubber band hard enough to remind you to resist those old habits.

Everything you'll need to know about planning a wedding can be found in Abby's booklet, "How to Have a Lovely Wedding." To order, send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Wedding Booklet, P.O. Box 447, Mount Morris, Ill. 61054. (Postage is included.)

DEAR ABBY: My husband is bisexual. I have known it since the third year of our marriage, but I expected him to be faithful, so I figured his fantasies were his own business. Well, as it turns out, he has not been faithful, and he is HIV positive! We have two small children, and he is a good father. We have a lot in common, we rarely fight, and I love him.

But now the BIG problem: To be blunt, I would miss the sex and will not be unfaithful. Also, there is the whole AIDS problem. Will he get sick? Will he infect me or the kids? Can my children have their friends over? Should I be sterilizing the dishes and the towels? What and when do we tell the kids? Our families? He wants to stay married; now I'm not sure I do. I have been to a counselor several times, and I still can't make up my mind.

Please do not publish my name or location, for obvious reasons! -- HIS WIFE

DEAR WIFE: I directed your questions to Dr. Merv Silverman, president of the American Foundation for AIDS Research. His response: "Unless more effective treatments are developed, eventually almost all HIV-infected individuals will have symptoms and, ultimately, AIDS.

"The only way your husband can infect you is through unprotected penetrative sexual activity. Will he infect the children? No.

"Your children can have friends over, and it is not imperative that dishes and towels be sterilized. Studies of households with an infected individual have shown absolutely no transmission of the virus unless there was unprotected sexual activity with the infected person.

"What and when to tell your children depend upon their ages. Since a person can look and feel well for years, it is probably not necessary to tell your small children until the symptoms start appearing.

"What and when to tell your families depend upon the relationship you have with those family members. Remember, however, that this disease is very difficult to deal with alone."

As to whether you should stay married, only you can make that decision. Regardless, you should be tested for HIV because, if you have been infected, you, too, should be under a doctor's supervision.

DEAR ABBY: My husband (I'll call him Barry) received an invitation to the wedding of his first cousin -- I'll call him Joe. I realize that the wedding invitations were sent out by Joe's fiancee, whom we have never met, but it was addressed only to my husband, Barry. We have been married for 15 years and have two children. We see Joe only once or twice a year and he knows that we are married.

Am I to assume that I am not invited to this wedding? Or am I to assume it was an oversight on the part of Joe's fiancee? Also, are the children invited? -- BARRY'S WIFE

DEAR WIFE: Your husband should call his cousin Joe, and explain this dilemma. I hope Joe will advise his fiancee that cousin Barry has a wife and two children, after which you will probably be invited. But don't bring your children unless they are specifically invited.

This one's for everybody, from teens to seniors! To purchase Abby's new booklet, "The Anger in All of Us and How to Deal With It," send a long, business-size, self-addressed envelope, plus check or money order for $3.95 ($4.50 in Canada) to: Dear Abby, Anger Booklet, P.O. Box 447, Mount Morris, Ill. 61054. (Postage is included.)