Our clinical experience based upon N-944 cases of tinnitus seen in the interval between November, 1977 and 30 December, 1982 has taught us the importance of the responsibility of the professional to the patient who presents with a chief complaint of the symptom of tinnitus. The primary goal is to attempt to control the tinnitus. The patient afflicted with this symptom is seeking a professional who can cure this complaint. The experienced professional(s) involved realize that no cure exists at this time. Multiple discipline(s) have become involved in this effort. All share common responsibility (ies).

To allocate sufficient resources to clinical services or to research and development in the most effective way possible, statistics are needed on the prevalence of the condition in question for various degrees of severity. For the United Kingdom, such data for tinnitus have become available from two recent large-scale studies. The first is the National Study of Hearing (NSH) which is being conducted by the Medical Research Council's Institute of Hearing Research from its headquarters in Nottingham and its clinical outstations in Cardiff, Glasgow, Nottingham and Southampton. It started in 1978 and is now entering its third phase. The second study is the General Household Survey carried out in 1981 by the UK Office of Population Censuses and Surveys (OPCS). The rationale and methodology of the NSH and the prevalence data obtained up to the present, together with those from the OPCS survey, will be given in this paper; the demographic data and the clinical aspects of the study will be presented in the accompanying paper (IHR, 1984).

This report has provided a brief survey of the Tinnitus Clinic population as it appeared near the end of 1981, when 1806 patients had been seen. That number is probably sufficient to provide satisfactory statistical reliability for the observations cited here. It should be mentioned that the Tinnitus Clinic has continued to accumulate cases, at the approximate rate of 30 per month, and at this writing the total number of patients seen to date is over 2300.

The data obtained from the first 1806 patients were collected under conditions that were not as homogeneous as those prevailing now, in that standardized testing equipment was not available until January 1979, and testing techniques were continuing to be revised even after that time. In addition a major revision of the patient questionnaires was undertaken late in 1981, with the result that much more detailed information is being obtained than was formerly possible using the old questionnaire format. Thus, we can anticipate that the next such survey of the Tinnitus Clinic population will offer considerably expanded and more detailed types of observations than those presented here.

Models play a crucial role in the development of our understanding of the auditory (or any other) system. They provide new insights from both a theoretical and practical point of view as well as providing a framework for summarizing existing knowledge. Most important of all, they provide predictions which can be tested experimentally. These experimental observations, in turn, will either serve to strengthen a specific model or, if theory and observation differ significantly, will provide new information leading to the development of improved models and hence an improved understanding of the processes being studied.

An auditory sensation follows generally as the result of the sequence stimulus, transduction, coding, transformation and sensation. This is then optionally followed by perception and a reaction. The stimulus is usually airborne sound causing movements of the tympanic membrane, the middle ear ossicles, the inner ear fluids and the basilar membrane. The movements of the basilar membrane are dependent on stimulus frequency: high frequency tones excite only the basal part of the cochlea, regardless of the stimulus intensity; low frequency tones at low levels only excite the so-called place specific region at the apical end but at high levels (above 60–70 dB SPL) cause appreciable movement of the entire basilar membrane. Basilar membrane tuning is as sharp as that of inner hair cells or auditory nerve fibers (Sellick et al., 1982) at least in the basal turn of animals that have a cochlea in physiologically impeccable condition.

This paper discusses the possibility of a localized peripheral origin of tinnitus. A working hypothesis is that tinnitus represents either aperiodic or periodic hyperactivity in the spontaneous activity of nerve fibers originating from a restricted place on the basilar membrane. The limited physiological data available support both hyperactive and hypoactive nerve fiber. Psychophysical data are not easy to interpret. Subjective descriptions and category scaling are too dependent on individual experience. Pitch matching can be reliable, but cannot distinguish between peripheral or central tinnitus. In one experiment we compared the masking of tinnitus to the masking of a pure tone, where the signal frequency and level were obtained from the tinnitus pitch and loudness matching. The results indicate that the broad tinnitus masking patterns are not typically due to the poor frequency resolution observed in sensorineural hearing loss. However, in a few subjects there was some correspondence between the shape of the tuning curve and the tinnitus masking pattern. In another study, we masked tinnitus with narrowband noises of different bandwidths. In some patients, there was a ‘critical bandwidth’ effect; wider masker bandwidths required greater overall sound pressures to mask the tinnitus. We conclude that the results from these studies taken together indicate that there are different types of tinnitus, some of which may have a localized peripheral origin.

The subjective nature of tinnitus is not the only feature which imposes difficulties upon the identification of tinnitus. The patients who must provide information about their tinnitus are greatly handicapped in this task and for the simple reason that there is very little vocabulary available to them. Thus it is not only important that the clinician listen very carefully to the patient but it is increasingly important that standardized tests be used to identify, measure and classify tinnitus.

Masking of tinnitus by acoustic stimuli seems to be a very simple phenomenon, reflecting everyday experience. The buzzing of a mosquito is drowned by the noise of a jet-plane. That is self-evident and does not need any explanation. It seems to be a perfect analogue to the masking of tinnitus. But if we look into these two situations more closely we find fundamental differences between them, which ask for interpretation.

The lack of loudness of tinnitus, as first pointed out by Fowler (1942), has been an item of confused concern ever since. The point being this: How can so weak a sensation produce such severity of stress? The present article deals with this item by attempting to provide a more objective psychological measure of severity of tinnitus. The U.S. Health Survey, which estimated that one out of five patients with tinnitus have it in its severe form, is but one example of differentiating mild vs. severe tinnitus. In the severe group, there are some for whom the tinnitus is constant and unrelenting, while for others the bad spells come and go without warning or reason. Whether constant or fluctuating, these patients perceive their tinnitus as a severe affliction which greatly degrades the quality of their life. We accept these subjective statements and ratings of their distress; however, there is a serious need for an objective measure of severity. The present report attempted such a measure by using the degree to which tinnitus was maskable by environmental sounds. The results correlated no better with ratings of severity than do the measures of loudness of tinnitus.

Regardless of the procedure used for the treatment of tinnitus, most clinicians initially attempt to determine the pitch and loudness of tinnitus. If the treatment of choice is a tinnitus masking program, two additional measures are made routinely. The first is an evaluation of the minimum masking level (MML) and the second is a determination of the amount of residual inhibition that occurs as the result of presenting a continuous stimulus over a period of time (generally for one minute).

What I have to say follows on very naturally from what Dr. Johnson has just said. I ought to explain that in the United Kingdom we work in somewhat different situations from yours in the United States, from the administrative point of view, but most particularly from the financial funding point of view. Under the National Health Service we are not paid per item of service; we get a lump sum on which we have to run our departments. If we see two patients or if we see a million patients it makes no difference. In many ways, if we see few patients we can give them a better service than if we see many. I realise that this is a concept which is perhaps new to those of you in the United States, that your income in fact comes from numbers of patients.

The concept of the critical band was first described in 1937 when Fletcher and Manson (1937) reported the results of an experiment conducted at the Bell Telephone Laboratories in which they used a random noise that had been shown to produce uniform masking throughout the frequency spectrum as the masking stimulus. From the results of this initial experiment, Fletcher (1940) was able to make two important assumptions concerning the masking of pure tones by thermal noise. The first assumption states that only the energy in a narrow band around the test frequency is instrumental in the masking of that pure tone and the energy outside this small band is superfluous. This small band of noise, Fletcher referred to as the ‘critical band’. Secondly, he assumed that at its masked threshold the energy of the tone and overall energy in the critical band were exactly equivalent. Using these assumptions, Fletcher computed critical bandwidths for several different frequencies. He found the critical band to be approximately 63 Hz for a 1000 Hz tone, to remain relatively constant for the lower frequencies, and to increase rather rapidly for high frequencies, reaching a width of about 500 Hz for a tone of 8000 Hz.

Noise exposure in the workplace and the recreational environment probably accounts for more new cases of tinnitus and hearing loss than all other causes combined. To an increasing degree, preemployment audiograms of late teenagers and those in their early twenties show noise-induced, sensorineural ‘notches’ greatest at 4000 or 6000 Hz with partial or complete recovery at 8000 Hz. Word discrimination tests, as typically evaluated in a clinical situation, show essentially normal findings although more difficult measures of consonant discriminations such as the California Consonant Test or conventional speech tests in a background of noise often demonstrate impaired word discrimination ability.

In the course of our clinical experience with tinnitus, the concepts of sub-clinical tinnitus; non-auditory tinnitus have developed. This has been an outgrowth of the critical emphasis placed upon the clinical history; and the attempt to objectivize the subjective tinnitus using auditory brainstem response recording (ABR). These concepts developed from observations and its correlation with the results of the neurotologic evaluation of our cases. These concepts are separate but can overlap.

Hallucinations are a well known aspect of chronic alcoholism. Visual hallucinations are much more common than auditory hallucinations, and both occur as part of the syndrome of sudden withdrawal following prolonged, heavy imbibition of alcoholic beverages, approximately the equivalent of one pint of ethanol per day for forty days. During the first 24–36 hours of alcohol withdrawal, acute visual and auditory hallucinations and grand mal seizures may occur prior to the disorientation and autonomic changes of delirium tremens, which need not follow invariably. Thus, some study of the patients in this stage is possible. The characteristic of the hallucinational content is its concreteness. The visual hallucination is of figures, faces and objects which the patient describes in concrete detail. The auditory hallucinations are of voices which the patient can describe, and quote what they are saying to him or to each other. Often the faces and voices are not familiar to the patient, and they may seem benign, although they are more commonly threatening. These hallucinations are distinctly different from those seen in schizophrenic patients. During the acute phase, the auditory hallucinations are localized as coming from the next room, or from the street, and not as being inside the head or in the ears.

Three hundred ten randomly selected male shipyard workers, with an average age of 56 years, with an average of 19 years with their employer, excluding workers with evidence of other otologic or relevant neurologic disease, were analyzed in terms of hearing loss, tinnitus, vertigo, and family history of hearing loss. The audiograms showed bilateral, symmetrical mid to high frequency hearing loss with SRT of 21 db and 85 per cent PB word discrimination. Eleven per cent had a family history of hearing loss, but this did not correlate with the patients' hearing loss, tinnitus, or vertigo. Fifteen per cent of the patients gave a history of vertigo. Tinnitus occurred in 43 per cent of right ears and in 41 per cent of left ears. Statistical analysis showed that the tinnitus did not correlate with hearing loss at any frequency in the right ear but correlated significantly with hearing loss at 2000 and 3000 HZ in the left ear! These were significant but small. Multiple correlational analysis indicated.

Objective pulsatile tinnitus on a vascular basis is a relatively uncommon auditory phenomenon. There are other forms of objective tinnitus which will not be covered in this discussion. The most common lesions are arteriovenous malformations near the temporal bone which are branches of the external carotid artery, such as the occipital artery, to the transverse or sigmoid sinus. Diagnostically, a patient can be entirely asymptomatic except for a pulse-synchronous objective tinnitus in one ear. There is usually no associated hearing loss, vertigo, imbalance or pressure. A sense of fullness may not be a constant problem but may be intermittent. The objective pulsatile tinnitus may not be a constant problem but may come and go for no apparent reason.

Tinnitus is a common symptom in a variety of otologic diseases and is frequently accompanied by loss of hearing. In recent years, the pervasiveness of the problem of subjective tinnitus has stimulated research with the following goals: to determine the frequency of tinnitus in certain diseases; to identify the anatomical source of ‘the noise’; to discover the neural mechanisms which generate this auditory pheonomena; and to find appropriate treatments.

It is extraordinarily appropriate that the organizers of the Second International Tinnitus Seminar should choose this occasion to honor Dr. Juergen Tonndorf. The printed summary of the Seminar objectives reminds us that tinnitus is a matter of concern to a remarkable spectrum of disciplines including audiology, neuropsychology, otology and psychoacoustics; and I know of no one person more thoroughly informed in each of those areas than our guest of honor, Juergen Tonndorf, M.D., Ph.D.