Zi Bolen once stopped a grocery store checkout line because her daughter Tammy was trying to tell her something and she couldn't figure out what. Tammy has severe communications problems, but "somewhere inside we knew she had something to say," Zi Bolen recalls.

"Pass me by," she directed the checker, but instead, "the whole store got into the act -- trying to help the delicate, wide-eyed, sad-faced child tell her mother what it was she wanted."

Bolen, sitting in a borrowed office at Montgomery County's Rock Terrace High School -- where she has spent a lot of time pushing and promoting, even badgering for special education equipment and attention, on Tammy's behalf -- remembers that in those early days, nearly a decade ago, "Tammy would get so frustrated, she would just turn away and cry. She never threw tantrums like some children, she was just so sad . . ."

To speak and be understood, to hear and comprehend, these are faculties so basic to humanity that the lack of any one of them can cause catastrophe. Inability to communicate makes the victim feel a little less than human -- set apart, isolated, cut off not only from the stimulation of others, but from help, comfort, even from love. Yet some 24 million Americans -- about one in 10 -- suffer to one extent or another from what the experts call a "communications disorder."

The largest group -- an estimated 17 million -- is the hearing impaired. But there are also the children -- like Tammy Bolen -- who cannot learn to speak. Or the adults from whom speech has been somehow excised -- by a stroke, a brain injury, a cerebral "accident" like an aneurysm. Or the paralyzed -- stroke or accident injured or suffering from such illnesses as cerebral palsy, multiple sclerosis, amyotrophic lateral sclerosis (ALS) or Parkinson's disease, among others -- who probably can hear and understand, but who can give no acknowledgment.

A communicative problem can be as simple as a harsh regional accent. Or as oblique as a minuscule neuronal abnormality deep inside the brain. There can be a structural block or paralysis that makes it impossible for a tongue to form a certain sound, or a glitch in a nerve pathway in the brain's speech center that produces a stammer or a stutter. It can be genetic or a defect of birth, or induced by drug, either abused or prescribed, or by illness or head injury.

Only recently have specialists grasped the full implications of an inability to communicate properly. Many specialists in treating such disorders are still finding their ways blocked by outmoded beliefs, too little public information about what can be done, too few facilities outside of metropolitan areas. All too often, a pediatrician will soothe a worried mother with, "Oh, he's just a little late talking . . . he'll be fine."

Nevertheless, the last decade or so has seen an increase in trained specialists, new techniques, electronic technology and a rapid and continuing growth in knowledge about how the human learns to communicate, about what can go wrong and how disorders can be either rectified or, better still, prevented.

"What happens to persons who are unable to speak," says Sarah Blackstone, a speech pathologist from the Johns Hopkins Medical Center's Kennedy Institute in Baltimore, "is that it affects them socially, emotionally, educationally, vocationally.

"Human beings are wired to understand and construct language. A whole lot of the brain activity in the left hemisphere is taken up in this, and it's almost impossible to prevent a child from learning language. It is innate in our ability to encode and decode symbols. So without thinking about it, we learn incredibly complex things about syntax, grammar, about sounds."

Research on how the brains of infants and young children develop now suggests that they continue to develop "not just in early infancy," says Blackstone, "but through ages 5 and 6, so that this kind of [language] data storage and interpretation is what allows us to process linguistic information.

"That's why," she says, "it is so easy for the young child to learn a second language and so difficult once our little brains are coagulated." And that is why it is so important "to see these kids as early as possible. With a 3-year-old, for example, who isn't talking, you don't know whether they will or not, but that doesn't mean you sit around and wait, because they still have things to say and express."

In order for these innate abilities to be realized, the human "output" system, the so-called "motor strip," ranging from tongue and palate to brain stem and left hemisphere, must be properly developed. So must the "input" system -- the hearing and processing apparatus.

Tammy Bolen was about 3 years old when her parents suspected something was seriously amiss.

Then began a series of consultations and visits to neurologists, hearing specialists, language specialists, clinics and universities. Tammy, for reasons never clearly defined, apparently had brain damage affecting her motor strip. She could not speak at all, and although her hearing was mechanically normal, she had difficulty processing what she heard.

Speech pathologists have found sign language a useful technique for children like Tammy, but although Tammy learned the signs in her preschool days, her motor problems extend to the use of her fingers, so that she has what her mother calls a "lazy sign."

Eventually the Bolens found Sarah Blackstone.

Blackstone gave the Bolens two things that have helped transform Tammy into an outgoing and determined 13-year-old, still severely handicapped, to be sure, but hardworking, increasingly able to express herself and now often visibly happy and excited and increasingly able to "say" so, although not always in words.

One thing Blackstone introduced to the Bolens was Bliss Symbolics, a system of conceptual symbols that transcend traditional language.

Charles Bliss, Sarah Blackstone explains, was a holocaust survivor who emigrated from Germany to Australia after his liberation. He devoted his life to the creation of an international language which he envisioned as the answer to the world's problems, the perfect communication that would never again permit the recurrence of the horror he had experienced.

What came out was a kind of conceptual hyroglyphic -- simple, ingenious, creative. But the Bliss language was almost universally ignored until a Canadian therapist thought it might be useful in treating handicapped children.

Indeed, says Blackstone, it has helped revolutionize therapy for communicative disorders in very young children. Now, she notes, there is a Bliss Institute in Ontario and there are Bliss-trained therapists throughout the world. Although "Bliss was unable to accomplish his goal with the so-called normal person," says Blackstone, "he has certainly made a tremendous contribution to the child who has a lot to say, but isn't ready to [or cannot] spell yet.

"The years between about 2 1/2 and 8 or 9 are years of language-rich development where kids are nonstop communicators. This system has really provided some options to those [handicapped] children so that instead of just pointing to a picture, they actually combine symbols to express concepts."

Along with the Bliss language, Blackstone brought the Bolens the world of the home computer.

Tammy Bolen uses her Apple computer with a Bliss Symbolics software program along with a voice synthesizer -- in her case a Votrex. At Rock Terrace, Montgomery County's school for special programs, the school system's speech pathology department is trying out new, increasingly portable, increasingly intelligible "augmentative" speech aids.

Zi Bolen keeps abreast of the latest electronic augmenters and Tammy, at home on a keyboard, quickly adapts to a new model presented for her experimentation. On this day she is offered a portable board whose electronic voice can help her conduct a reasonably rewarding conversation or can even ask for help from a stranger, if need be. She "converses" with a photographer, giggling as the atonal, mechanical voice carries her end as her fingers direct via the keyboard.

Tina Williams, one of two county speech pathologists who are designated as "augmentative communications consultants," is a trained Bliss therapist, the first in the county school system. She particularly likes a synthetic voice called Minspeak, she says, for its intelligibility and simplicity.

The perfect solution for Tammy is still elusive, but using some signs, some sounds that she makes, along with the synthesizer, her path to communicating is being forged, convoluted though it may be.

Blackstone is currently on leave from the Johns Hopkins-based Kennedy Institute to develop special projects in speech and language technological assistive devices for the American Speech-Language-Hearing Association (ASHA), the professional organization for some 45,000 audiologists, speech-language pathologists and therapists.

Voiceless children are not the only beneficiaries of high-tech help. Blackstone cites a physician who was writing articles for medical journals up to the time of his death from ALS. He operated his computer by movements of his eyebrows, the only movement left to him as his illness progressed. Other increasingly available devices, at prices that are no longer prohibitive, may be operated by light beams or eye movement. A 13-year-old Pittsburgh boy with cerebral palsy recently used a voice synthesizer programmed in both English and Hebrew for his bar mitzvah. The sophisticated computerized voice performed the traditional Herbrew chants.

Tammy Bolen's problems, on the surface at least, seem not too different from those of stroke and accident victims suffering from aphasia. Blackstone emphasizes that although "some of the symptoms are similar to what we see in adults, in a developing brain we can't make the giant leap that the same kinds of things are happening that happen in the adult mature brain that has had some kind of insult to it."

The insult to Jacqueline Doolittle's brain came in an automobile accident.

It was 20 years ago, but Doolittle can describe in detail the terror she felt for six weeks. She had the condition known as aphasia -- loss of the ability to make sense of language.

"It's hard to separate what I've said about it over the years from what I actually remember," she says now, but "it is immensely frightening and nobody explains what is happening. And if they do, you don't hear it or process it." She couldn't move. She couldn't talk. She "knew" that she was being kept prisoner in a country farmhouse, but she didn't know why.

"I knew everyone there had made up the story of my being in an automobile accident and I had to get the word out. I believed the nurses were guards who were keeping me tied down and medicated so I couldn't move and I couldn't talk and I tried desperately to find some way out of this blind alley."

"I was just trapped."

Doolittle's head trauma resolved itself spontaneously, but she continued to have some memory problems, and after about a year "I thought maybe if I took a course I might possibly get back some of the ability to concentrate and function mentally that I'd had before. And I thought as long as I was taking courses, I may as well take them in the area of speech and language."

Almost without noticing, Doolittle acquired another degree and became certified to work in the field. "I realized," she says, "that there had really not been anybody who worked with me, and I think if someone had come in and worked consistently with me, I might not have had the fearful experience I had.

"The fact that I couldn't really understand what they were saying, didn't accept what I could understand and couldn't speak, along with the fact that they weren't treating it, was also part of the thing that made me feel I was just being manipulated somehow."

Today Doolittle is a speech pathologist at the White Plains Medical Center in New York. She works with aphasia victims, many of whom are stroke patients, hoping to ease some of that isolation she recalls from her own experience. In the introduction to his play "Wings," Arthur Kopit credits Doolittle with much of the understanding of what goes on inside the aphasic brain. She was, he wrote, his "touchstone."

Yet, she says, "I'm still in the position where I have to fight to see some of these patients. Someone still has to advocate the need for interceding. Some physicians think, perhaps rightly, that these people will get better on their own, but they don't seem to realize that four or five weeks of terror, even if it does lift, is still four or five weeks of terror that might be eased.

"And if the aphasia is going to be prolonged, they certainly need it, and the family needs it, the whole psychosocial area in which this person is living requires this kind of help so that family and friends can meet these people more than halfway."

Researchers have demonstrated that aphasia patients benefit from therapy by speech pathologists and that families who learn how to apply some of the techniques themselves can have a measurable impact on the improvement of these patients.

James B. Lingwall, director of professional affairs for ASHA, notes that speech-language-hearing professionals are not included in all cases where their intervention could be helpful. For example, technology and techniques permit testing newborn infants for hearing deficits -- but how often is an audiologist present on an obstetrics ward?

"Our relationships with other professionals are crucial," says Lingwall. The field is relatively new and the major strides are relatively recent so that "sometimes neither the public nor the doctors know we are there, partly because the strong social service element among our members may have kept them from being good marketers."

Many of these professional specialists in speech, language and hearing difficulties find themselves ignored, patronized, sometimes actually opposed by physicians who, although often not as well versed in the specific problem, are loath to recommend specialists not of the medical community. Part of ASHA's mission is to help chip away at the prejudice, little by little trying to prove themselves as important members of a medical team, rather than taking a confrontational stance or suggesting that they are competing.

"There has to be a team approach to these problems," says Sarah Blackstone. "One profession cannot solve the problems alone."

Says Lingwall: "Communication is really the life blood of your everyday existence, but it is taken very much for granted. It is kind of an abstract process and it's only when something goes wrong that we notice."