In the first category, there is the very young child, where the cause of defective hearing may be prenatal, or it may be related to certain natal or immediately postnatal occurrences, many of which center around the field of obstetrics or postnatal infections. In our clinical load, which is large, are tiny infants and preschool children. We estimate that about 40 percent of the children we see who are badly disabled from very early times, immediately following birth or prenatal, have preventable disabilities in medical terms with further knowledge and adequate control of, say, birth circumstances. With the improvement of clinical methods and the further knowledge needed of the basic operation of the hearing mechanism, about 40 percent of the number of cases in early childhood involving serious hearing impairment can be wiped out.

Among school children ranging in age from approximately 6 to 14, a conservative estimate, based on a highly adequate survey system, is 5 percent of hearing disability as a general national figure. For various reasons, a large percentage of that is remediable.

In the adults up roughly to middle age, however, if you wish to define that, I think it is a safe generalization to say about 50 percent of the cases of hearing disorders in adulthood could be prevented by adequate and early controls, because many of them have their onset in childhood.

In the fourth category there is a field that must be approached with complete humility, and that is the whole area of the hearing disorders that occur with old age. I think it is safe to say that nobody in this country or in the world can at present analyze the physiology of old age that results in the breaking down of hearing as one gets older.

There are many details I am sure you will have questions about as to the known hearing impairments and the known means of remedying them. We can think and talk in about three major categories.

The first category has to do with prevention as a general, broad approach to a severely disabling problem or trouble.

The second has to do with medical and surgical therapy designed to cure, mitigate, or reverse symptoms.

The third category is in the general realm of rehabilitation or special training necessary to be carried out when one is faced with permanent hearing impairment which has not been prevented and which cannot be cured.

I would like to comment on one more figure which has been derived by as careful a study as yet made in the field, that at the present time approximately 300 million man-hours of productive effort are lost per annum from causes directly traceable to hearing disorders. Now I would like your indulgence to hear Dr. Glorig.

Mr. HESELTON. Are there any questions?

Mr. THORNBERRY. Mr. Chairman, I have a few questions, but I thought I would wait until Dr. Glorig got through. Dr. Hardy, let me ask you this: In what field or category do you put those people who lose their hearing at an early age? My parents are both deaf, and I have been associated with deaf people all my life, and most of those I know have lost their hearing in infancy or at birth; at least, that was their history. In what category do you put those people?

Dr. HARDY. I meant to indicate, though perhaps I did not do so clearly, that many of those cases can be categorized under prevention, and the rest have to go under rehabilitation and training.

Mr. THORNBERRY. What is the cause? Does the loss of hearing in most of those cases occur at birth or just after birth? In the history of deafness, do most cases occur in infancy?

Dr. HARDY. About 40 percent of the clinical cases involve a hearing disorder that is prenatal, natal, or immediately postnatal, and about 40 percent are medically preventable.

Mr. THORNBERRY. What percentage did you say are medically preventable?

Dr. HARDY. Forty percent. For instance, the so-called RH factor, neonatal, involves some broad changes in the blood system which, for some reason take their toll, among other things, in the hearing mechanism. That is preventable more now than it used to be. That has not been recognized as an entity more than 13 years now, and the field is slow in going through.

Among a large group of schoolchildren, we find about two-thirds of the problem in total are postnatal, coming from disease entities that are quite well known. Most virus diseases can cause hearing impairment. When you look back over the record of the years, when it was unusual if not impossible to carry out presently known diagnostic procedures, the temptation was to call it congenital deafness. We are beginning to find out now that that was not true. Some of the problems do date from or predate birth, but many others normally accrue from well-known diseases in infancy.

For instance, the incidence of children who suffer severe impairment from measles is relatively little. No doubt there are those who suffer that impairment by a nerve-type destruction of the hearing mechanism and that is a kind of problem that simply is present. When the nerve structure is damaged there is nothing to do about it. Mr. THORNBERRY. That is the type that results from measles? Dr. HARDY. Yes. That is one disease and, of course, there are other viruses.

Mr. THORNBERRY. I have a number of questions, but you indicated Dr. Glorig might want to leave early and, rather than hold him up, I will let him go ahead. There are a number of questions in this field in which I am personally interested.

One question which I might ask at this time is this: Doctor, in my contacts with the deaf I think there has always been the feeling that the cause of deafness is largely, as he termed it a while ago, due to being born deaf. My experience is that generally deaf people feel they were born that way.

Dr. ELSTAD. When you take into consideration the deaf as a group, about 30 percent are known to have been born deaf.

Dr. HARDY. That fits the picture very closely.

Mr. THORNBERRY. Is that what you think, too, Dr. Hardy?

Dr. HARDY. That is about the general pattern.

Mr. HESELTON. I take it that someone will give us information as to the type of research that has been done and what can be done. Dr. HARDY. Yes, sir. We will try to get to that.

Mr. HESELTON. Will you please proceed?

STATEMENT OF DR. ARAM GLORIG, HEAD, AUDIOLOGY AND SPEECH CORRECTION CENTER, WALTER REED ARMY HOSPITAL, WASHINGTON, D. C.

Dr. GLORIG. First, may I explain why I have to leave early? There is a large national committee meeting which is to be held today to discuss this very problem in relation to industry and in the Army, and I am a member of that committee and I should get back as soon I can. I apologize for having to do so.

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To go on a little bit into the problem of hearing losses, certain school surveys indicate that about 5 percent of the children are found to have hearing losses which need audiological attention and that means hearing losses which may be prevented provided they get this audiological attention.

A little more of the problem is represented by the military and veterans' problem. For example, the Veterans' Administration is paying 10-percent disabilities-and in some instances a great deal more to about 90.000 men at the present time for hearing losses sustained during World War II. This amounts to quite a financial problem when you break it down a little. That is in compensation alone. Now, for hearing aids issued to veterans, since 1949 there have been about 40,000 hearing aids issued at a cost of about $120 each, and when you figure that out it comes to quite a bit of money also. This has nothing to say about rehabilitation and reissue and batteries. The battery problem alone amounts to somewhere near one-half to threequarters of a million dollars a year to supply batteries for these individuals who have hearing losses and who are using hearing aids.

The Army in the last few years and part of 1945, 1946, and I believe back as far as 1944 rehabilitated 12,000 individuals who sustained hearing losses in the Army, and this is in addition to those which I spoke about in the Veterans' Administration. The Army at the present time, during a so-called peace regime, is rehabilitating about 1.200 men a year. These are both from the Army and the Air Force. The Navy figure is not that large. We issue some 600 hearing aids per year at the center, and to give you a little bit of an insight into what this means to the Army at the present time, we have about 4,500 or 5,000 men in the armed services who are using hearing aids. The rehabilitation has been so thoroughly done that 98 percent of the men we have at the center go back to military duty. Our only restriction is that they not be put in an actual combat situation. I am merely mentioning this to show you that rehabilitation can prevent some of this 300 million man-hour loss, providing we do something about getting it done among the civilian population.

The problems in industry, which are just recently being recognized, although it has been present since 1885, when hearing losses were referred to as "boilermaker's deafness," are now being studied. At the present time it is coming into the limelight due to the number of compensation payments which have come about and the potential which is growing every day.

Mr. HESELTON. What does that amount to?

Dr. GLORIG. It varies from $4 million to $7 million in deafness caused by industry at the present time.

Another point of the problem would be that when men are tested prior to entering into an industrial situation which is a noisy industry,

25 to 30 percent of these men have significant hearing losses, which means that the problem of man-hours mounts rapidly when you start paying for the cases who have hearing losses from the therapy standpoint.

Speaking as a physician-and I am a physician in this field-there are two types of hearing losses. One is the type which affects the canal which conducts the sound to the nerve part of the ear, and that is called conductive deafness, and then there is the nerve type deafness which affects the nerve transmission itself.

The conductive type is, in the main, provided it is found soon enough and something is done about it, amenable to treatment, to therapy of some kind or another-surgical, drugs, or medical management.

The nerve type of deafness is irrecoverable in spite of any treatment we know of today, and I can say, frankly, that at the present time there is no treatment available for deafness which is of the nerve type and, believe me, the nerve-type deafness is a considerable problem in the whole, particularly since we are getting to be a noisy civilization and causing considerably more deafness among workers. This problem is summarized by the fact that a company which we have been working with, where men who have worked in excess of 10 to 15 years at certain machines, have a relatively common incidence of certain loss of hearing. One hundred percent of these men that have worked in excess of that many years have a hearing loss. This 100 percent is not compensable, but if they go on continuing in this type of work for more than 20 or 25 years, all of them will be compensable.

Dr. HARDY. You mean if they continued at that noise level?

Dr. GLORIG. Yes, sir. Well, the noise level that I am talking about is not much louder than I am speaking at the moment. My voice, if it were measured at the moment, would probably be at the level of 80 or 85 decibels, and if we measured the noise in industry, it would run over 100 decibels and can go up as high as 135 or 140 decibels. If we get into the jet problem with industry, they go even higher.

Dr. HARDY. May I interrupt once more? There will be some comments from time to time in which this term "decibel" will be used. That is a physical measure of the ratio of sound intensity. It works in a logarithmic fashion. If you take 20 decibels and multiply it 10 times, the difference at a 100-decibel-noise factor in a factory is not a ratio of 10 to 120, but a ratio of 1 to 10, which is why, as these figures go up, the traumatic effect is that much more serious.

Dr. GLORIG. I think, then, our therapy for the type of disease we are talking about lends itself more to prevention of the disease, and we are in hopes, particularly the committee on conservation of hearing of the American Academy of Ophthalmology and Otolaryngology, during the preschool days at our baby clinics, of discovering the hearing losses at an early enough age where something can be done about it or prevent a hearing loss from occurring from the ordinary diseases that we see in preschool children.

In several of the States-and too few at the moment-they are having school surveys where every third or fourth year every child is tested to see whether or not his hearing has changed from the previous test. I suppose a relatively good educated guess would be that 1 out

of 5 children in the country is now receiving such a test, and this is a very poor percentage.

The public in general should have hearing tests. As a matter of fact, at this very moment there is such a testing situation going on in Alexandria, where the public-health people over there have set up a testing program once a year, and individuals come in and get all sorts of tests, and, thank goodness, hearing tests are among them, because I believe among the general public there is a lot of hearing loss which is not discovered until it is too late because they do not have hearing tests done as they would have blood-pressure tests or blood tests or any other kind of tests.

In industry at the present time we are trying to get them to employ preemployment and preplacement tests so that the individual who has normal hearing can be protected by wearing ear protection, and we feel if ear protection is instituted in industry to the degree which it should be, the same as glasses are for eye injuries in industry, we can prevent almost the entire industrial hearing-loss problem. It is just as simple as that, gentlemen. Once, however, this hearing loss has been attained or suffered, there is no cure for it.

As I am here to represent the American Hearing Society, a few figures about the society might be in order.

Our aim is conservation of hearing, and I think there is no better aim for a hearing society to have, because we as physicians are charged with the conservation of hearing.

The American Hearing Society has 115 chapters, and they have spent in 1952, including the national headquarters, about $950,000 on the problem of deafness. I prefer to call it hearing loss. About 60 percent of this is for diagnosis, care, rehabilitation, testing, and so forth. About 20 percent is for public education, and, believe me, I think perhaps if the figures were reversed you would get a better understanding. The public needs a lot of education regarding the hearing-loss problem. Twenty percent is for administrative problems.

To show you what is being done at the present time for the hearing-loss problem, the military, in the form of the Army, Navy, and Air Force, have combined with the National Research Council to form what is called a committee on hearing and bioacoustics. This committee is meeting today and is working primarily with the problem. of hearing losses in the Armed Forces, but through its connection with the National Research Council and some of its civilian members we hope they will have a great effect on what is happening to the civilian hearing-loss problem as well.

The Army has done a great deal of research work-that is, the military forces, I should say. In the early years of the war and also the later years of the war this has been done. Most of this has been done on a normal hearing to determine how the hearing problem affects communities, and so forth. However, later during the war the Army led the field in the rehabilitation problem along with the Navy. I stated they rehabilitated some 12,000 men.

The Veterans' Administration at the present time has set up a very fine testing system, and they also have some very fine rehabilitation centers for their eligible individuals. They have set up a much better rating schedule for paying compensation, and this is a terrific problem. As a matter of fact, industry at the present time is wrestling