200 years testing hearing disorders with speech, 50 years german speech audiometry -- a review

FROM THE BEGINNIGS TO CLASSICAL SPEECH TESTS: The need for classification of different degrees of hearing disorders first arose when it seemed possible to treat deafness. Grapengiesser in Berlin 1801 had applied galvanic current to the ears of deaf children and reported some success. Pfingsten in Kiel in 1804 using this method was the first to use speech in diagnosing different degrees of deafness. He divided speech sounds into three classes: vowels, voiced consonants and voiceless consonants. Itard in Paris in 1821 gave a classification of five classes according to which sounds could be perceived, starting from normal speech to thunder and the bang of a gun. Schmalz in Dresden 1846 noted the range within which speech was understood thus introducing the concept of hearing distance. Helmholtz in 1863 had demonstrated that vowels are composed of pure tones. Wolf in Frankfurt 1871 tried to align all speech sounds from the lowest frequency (tongue-R = 16 Hz) to the highest (sh = 4096 Hz) and measured the hearing distance for each sound. Following these suggestions word lists based on the predominant frequencies were compiled in a number of languages including Japanese. SPEECH AUDIOMETRY: This chapter is devoted to Karl Heinz HahIbrock, Freiburg, who was the founder of the German speech audiometry. Hahlbrock followed the American authors of the Psycho-acoustic Laboratory at Harvard, in particular J. P. Egan (1948), using statistical methods for composing lists of words based on the relative frequency of speech sounds and phonetically balanced between the different groups. He finally presented a test comprising groups of two-digit numbers and monosyllabic words. Hahlbrock died in 2003 exactly fifty years after the presentation of his test. A short account of his life is given. THE FOLLOWING DEVELOPMENT: In the following years various other types of speech tests were elaborated using sentences, distorted speech, diotic and dichotic presentation partly aimed at fitting hearing aids, partly with the aim to diagnose central hearing disorders. Hahlbrock's test, however, remained the standard for evaluating speech reception and discrimination. DISCUSSION: One of the fundamental problems in testing speech discrimination is that there is no catalogue of phonemes common to all languages or regional accents. Untrained not native speakers often do no perceive certain sounds having a partial auditory agnosia. They cannot distinguish between e. g. 'hand' and 'and' or 'end' and 'ant', but the examiner must decide if the word presented was repeated correctly or not.     

Examination of 1,300 children for incidence and therapy of hearing disorders in pediatric speech disorders]

This study presents the results on 1305 children with speech disorders. The examination includes ENT-inspection, audiometry, speech-evaluations and if required, psychological tests. In 48% we found hearing losses, most frequently in the age up to four years. In 95% hearing losses were fluctuating about 20 decibels, caused by malfunction of the tube or by adenoids, not even in autumn and winter, but also all the year. In this case, fluctuating hearing function reduces the total hearing input over the year. In only 5% we found cochlear hearing loss. In hearing impaired children speech development was significantly more depressed in all dimensions in comparison to normal hearing children. This study does impressive demonstrate the necessity of follow-up microscopic evaluations of the tympanic membrane and audiometry as well as the consequence operative therapy including adenoidectomy and insertion of ventilation tubes. With this concept, only 37% of the children required speech therapy.     

Metabolic disorders in vertigo, tinnitus, and hearing loss

Vertigo, tinnitus, and hearing loss are common complaints among populations of industrial countries, especially in persons older than 40 years. Numerous agents are known to incite vertigo, tinnitus, and hearing loss, among them hyperinsulinemia, diabetes mellitus, and hyperlipidemia. In this study, we proposed to assess the occurrence of hyperinsulinemia, diabetes mellitus, and hyperlipidemia in patients suffering from vertigo, tinnitus, or hearing loss of unknown origin. Results of various tests in 48 patients were compared to those in 31 control subjects. Assessments of body mass index, blood pressure, and laryngological, audiometric, and electronystagmographic parameters were performed in all study participants. An oral glucose tolerance test was used to evaluate insulin levels, and lipoprotein phenotyping served to determine cholesterol, triglyceride, and lipoprotein levels. Patients were found to be significantly more overweight (on the basis of body mass index) than were the control subjects. Hypertension was more common among patients than controls, but the difference was significant only between the men in the two groups. Disturbances of glucose metabolism were found in 27.1% of patients but in only 9.7% of controls. Diabetes mellitus was not present in any controls but was identified in four patients. Hyperinsulinemia was almost twice as common in patients as in controls. Only the occurrence of hyperlipoproteinemia seemed not to differ between patients and control subjects. We conclude that such disturbances of glucose metabolism as diabetes mellitus and hyperinsulinemia may be responsible for inner ear diseases, whereas the role of disturbances of lipid metabolism remains vague.     

Pre-implant evaluation of speech and hearing

This paper describes an approach taken to predict, in advance of invasive surgery, whether a permanent cochlear prosthesis will serve as an aid to hearing in postlingually deaf adults. Nine subjects were implanted transtympanically with a temporary single-channel round window electrode. Over the course of one week a number of tests were conducted, including (1) the measurement of current thresholds over a range of frequencies for sine, square and biphasic pulse waveforms and minimum detectable gap between a pair of short bursts; (2) the discrimination of elementary speech features of live voice such as interruption, intonation, and stress placement; (3) the recognition of consonants, and (4) speech tracking. Eight subjects were able to appreciate changes in loudness, pitch, duration and temporal gap for frequencies below 1 kHz. All showed significant improvements over listening with high-power hearing aids in discriminating a variety of changes in elementary speech features. It was found that the recognition of consonants and speech tracking was heavily dependent on lipreading.     

Relationships among speech perception, production, language, hearing loss, and age in children with impaired hearing.

Eighty-seven primary-school children with impaired hearing were evaluated using speech perception, production, and language measures over a 3-year period. Forty-seven children with a mean unaided pure-tone-average hearing loss of 106 dB HL used a 22-electrode cochlear implant, and 40 with a mean unaided pure-tone-average hearing loss of 78 dB HL were fitted with hearing aids. All children were enrolled in oral/aural habilitation programs, and most attended integrated classes with normally hearing children for part of the time at school. Multiple linear regression was used to describe the relationships among the speech perception, production, and language measures, and the trends over time. Little difference in the level of performance and trends was found for the two groups of children, so the perceptual effect of the implant is equivalent, on average, to an improvement of about 28 dB in hearing thresholds. Scores on the Peabody Picture Vocabulary Test (PPVT) and the Clinical Evaluation of Language Fundamentals showed an upward trend at about 60% of the rate for normally hearing children. Rates of improvement for individual children were not correlated significantly with degree of hearing loss. The children showed a wide scatter about the average speech production score of 40% of words correctly produced in spontaneous conversations, with no significant upward trend with age. Scores on the open-set Consonant-Nucleus-Consonant (CNC) monosyllabic word test and the Bench-Kowal-Bamford (BKB) sentence test were strongly related to language level (as measured by an equivalent age on the PPVT) and speech production scores for both auditory-visual and auditory test conditions. After allowing for differences in language, speech perception scores in the auditory test condition showed a slight downward trend over time, which is consistent with the known biological effects of hearing loss on the auditory periphery and brainstem. Speech perception scores in the auditory condition also decreased significantly by about 5% for every 10 dB of hearing loss in the hearing aid group. The regression analysis model allows separation of the effects of language, speech production, and hearing levels on speech perception scores so that the effects of habilitation and training in these areas can be observed and/or predicted. The model suggests that most of the children in the study will reach a level of over 90% sentence recognition in the auditory-visual condition when their language becomes equivalent to that of a normally hearing 7-year-old, but they will enter secondary school at age 12 with an average language delay of about 4 or 5 years unless they receive concentrated and effective language training.