[Evaluation of the perceptual equivalence of test lists in the Freiburg monosyllabic speech test]

[The adaptive use of the Freiburg monosyllabic speech test in noise with a reduced number of test lists]

BACKGROUND

Considering the different calibration and masking of the noise, the adaptive Freiburg monosyllabic speech test in noise (aFBE-S) and the Oldenburg sentence test in noise (OLSA-S) were shown to be comparable with respect to the accuracy of both tests in a previous study. However, the time requirement of the aFBE-S was significantly greater than that of the OLSA-S due to the adaptive measurement method. The purpose of this study is to theoretically determine whether the aFBE-S can be used with fewer test lists, given the low scatter of results, and to compare the results with those of the OLSA-S.

METHODS

Using the results of 40 otologically healthy subjects who had already been tested in randomized order with the OLSA-S and aFBE-S, the mean difference of the 95 % confidence interval (95 % CI) of the signal-to-noise ratio for 50% speech understanding (S/N50) of the aFBE-S was calculated for three, four, and five test lists instead of 7.5. In addition, the time required for the reduced number of test lists was determined and the results were examined in comparison with those of the OLSA-S.

RESULTS

In each case, no significant difference between the difference mean of the 95 %-CI of the S/N50 of the original aFBE-S, the aFBE-S shortened to 3, 4, or 5 test lists and the OLSA-S could be found. The time required for the aFBE-S with a reduced number of test lists was significantly less than for the OLSA-S in each case.

CONCLUSION

The aFBE-S is not inferior with a reduced number of test lists in comparison to the OLSA-S. This would allow to use the shortened aFBE-S theoretically.

Comparison of three calibration procedures for free-field reference speech audiometry

OBJECTIVE

In standards IEC 60645-1 and ANSI S3.6, the free-field equivalent earphone output level method is assumed as the reference for speech audiometry. Three calibration procedures for this method were compared in this study.

DESIGN

Speech audiometry was conducted with Dutch consonant-vowel-consonant words for the following conditions: 1. TDH39 earphones, 2. loudspeaker, and 3. free-field simulated with TDH39 earphones. The first calibration procedure was based on the empirically determined difference between the speech recognition threshold (SRT) with earphones and a loudspeaker. The second procedure was based on the theoretical free-field correction, derived from the known speech spectrum and the free-field to coupler difference. The third calibration procedure corresponded to the results of the free-field simulated speech material under earphones.

STUDY SAMPLE

The sample included 20 normal hearing subjects.

RESULTS

The differences between the observed SRT in the free-field and earphone conditions and the free-field and simulated free-field conditions were 7.1 dB and 0.6 dB, respectively.

CONCLUSION

The three calibration procedures for the free-field equivalent output method yielded approximately the same results, and therefore all appear to be useful for TDH39 earphones.

[Correlation between the APHAB questionnaire and the Freiburg monosyllabic test without + with noise]

BACKGROUND

Questionnaires, e. g. the APHAB, and speech-audiometry are the most used elements in measuring the success of hearing aid fitting (HAF). This study investigates the correlations between the results of the Freiburg monosyllabic word test without and with noise (FBE, FBE-S) and the results of the APHAB before and after HAF.

METHODS

Data of the FBE, the FBE-S, and the APHAB, generated within HAF of 156 subjects were analyzed. After exclusion of a normal distribution of the data, Spearman's correlation and Cohen's effect size were determined.

RESULTS

73 (46.8 %) of the 156 subjects were females, and 83 (53.2 %) males. No significant correlation could be found between the EC-, the RV-, and the cumulative ECBNRV-subscale and the benefit of HAF in the FBE and FBE-S (EC: ease of communication, BN: background noise, RV: reverberation). Most of the remaining coefficients of correlation had a weak positive effect size. A middle positive effect size could only be demonstrated for 6 combinations, for the EC-subscale mostly.

CONCLUSION

The not strong effect sizes could assume that the results in speech-audiometry and the APHAB are not independent and complementing each other as parameters of hearing loss and benefit in HAF. The effect size could be explained by individually different possibilities for the compensation of hearing loss.

[Audiological target parameters in clinical studies with implantable hearing systems]

A multitude of new implantable hearing systems and applications creates new options for pathologies which have been difficult to treat in the past. For many of these hearing systems preclinical technical methods to characterize devices and applications are limited. Therefore, clearly structured clinical investigations and trials are necessary to render results of devices and applications comparable for meta-analysis. Beside optimizing results in current applications, this is also essential for comparisons with established treatment options and differential indication criteria. Even during planning and design of studies, the timing of reference measurements and the choice of-on-off vs. pre-post comparisons in audiological testing decides the focus of the study. This applies equally to the choice for a monaural vs. a binaural test design, which decides whether the study will have the device or the overall result of the treatment in focus. Additional measures such as effective gain, coupling efficiency, and maximal possible intelligibility (WRS_max) can be performed with standard methods and equipment and enable better insight into functional principles of devices and applications. However, testing methods have inherent limitations that have to be taken into account for correct and meaningful interpretations. The use of standardized audiological instruments is essential and permits comparison of devices and treatment results. This is equally important for the creation of evidence-based differential indication criteria between different types of devices as well as for choosing the optimal treatment.

Die Verständlichkeitskurve für den Freiburger Einsilbertest im Störschall mit einem Signal-Rausch-Abstand (SNR) von 5 dB

Hintergrund

Der Freiburger Einsilbertest (FBE) ist seit Langem einer der wesentlichen deutschen Sprachhörtests. Seit einiger Zeit wird er auch zur Messung der Hörverbesserung im Rahmen einer Hörgeräteversorgung im Störschall verwendet (FBE-S). Mit dieser Studie soll eine Verständlichkeitskurve für den Freiburger Einsilbertest im Störschall mit fixem Signal-Störschall-Verhältnis von 5 dB bei verschiedenen Schalldruckpegeln bestimmt werden.

Methode

Im Herbst 2018 wurden 60 normalhörende, muttersprachlich Deutsch sprechende Probanden im Alter zwischen 18 und 31 Jahren in der Klinik für HNO-Heilkunde des Bundeswehrkrankenhauses in Hamburg untersucht. Das Sprachverstehen wurde mit einer Testliste des FBE mit einem Schalldruckpegel von 15 bis 90 dB und einem 5 dB niedrigeren Störschall in 5‑dB-Schritten gemessen. Anschließend wurden von den Verständlichkeitsquoten die Mittelwerte gebildet und die 95%-Konfidenzintervalle (95%-KI) bestimmt.

Ergebnisse

Es nahmen 29 weibliche und 31 männliche Probanden an der Untersuchung teil. Das mittlere Alter aller Probanden betrug 24,32 Jahre (±3,39 Jahre). In der Varianzanalyse für fixe Effekte mit der Verständlichkeit als abhängiger Variablen zeigte sich ein hochsignifikanter Zusammenhang zwischen den Schalldruckpegeln des Sprach- und Störschalls auf der einen Seite und der Verständlichkeit auf der anderen Seite (p < 0,001). Die gemittelten Verständlichkeitsquoten und zugehörigen 95%-KI sowie die Häufigkeitsverteilungen wurden tabellarisch und grafisch dargestellt.

Schlussfolgerung

Die Verständlichkeitskurve des FBE‑S ist im Vergleich zur Normkurve des FBE nach rechts verschoben. Die gemittelte Kurve des FBE‑S erreicht bei einem Schalldruckpegel von 70 dB und einem Störschalldruckpegel von 65 dB den Sättigungsbereich von 90 % Verständlichkeit (zum Vergleich: Der Sättigungspunkt von 100 % Verständlichkeit liegt beim FBE ohne Störschall bei 55 dB). Durch die hier vorgestellte Verständlichkeitskurve lassen sich individuelle Messergebnisse ohne und mit Hörgeräten besser interpretieren. Künftig sollte der Hörgewinn für Hörgeräte möglicherweise bei niedrigeren Schalldruckpegeln erfolgen als heute.

[Characterization of a closed-set logatome test : Documentation of audiometric data: discrimination function and reproducibility]

BACKGROUND

Logatomes, nonsensical combinations of consonants and vowels, are suitable for a precise capture and analysis of individual phonemes as fundamental modules of speech in audiometric diagnostics.

OBJECTIVE

The aim of this prospective study was to capture the audiometric characteristics of a closed-set logatome test. The slope of the discrimination function at the speech reception threshold (SRT) and the reproducibility were analyzed.

MATERIAL AND METHODS

A set of 102 intensity varied and randomized logatomes were presented in the form of consonant-vowel-consonant to 25 hearing unimpaired adults. The measurements were performed in a free field setting and were each repeated after a 2-week interval. The subjects were requested to repeat the heard logatome in a closed response test of 10 items per sound item on a touchscreen.

RESULTS

The slope of the mean discrimination function at the SRT was on average 4%/dB; however, the mean discrimination function slope was steeper for the initial consonant than for the final one. The differences of the test and retest results at the SRT showed a standard deviation of 13% for consonants. These differences were normally distributed. There were no significant differences between test and retest.

CONCLUSION

The slope of the discrimination function at the SRT appeared to be shallow but was comparable to established word tests. Finally, there was no evidence of a learning effect in the retest, which emphasizes the low redundancy of the speech material and makes it an attractive complementary option to routine audiometric diagnostics.

[The adaptive Freiburg monosyllabic test in noise : Development of a procedure and comparison of the results with the Oldenburg sentence test]

BACKGROUND

Whereas sentence tests are commonly performed using an adaptive procedure, this method has not yet been transferred to the Freiburg monosyllabic speech test, the most important word test. When using different procedures, a comparison of results between sentence and word tests is not possible. Therefore, an adaptive procedure which has proven itself in sentence tests was transferred to the Freiburg monosyllabic test in noise. The results of the new procedure were compared to the standard of sentence tests, i.e., the Oldenburg sentence test.

METHODS

The adaptive Freiburg monosyllabic speech test and the Oldenburg sentence test were applied in 40 otologically normal subjects in a randomized order. Results were analyzed with respect to time requirements, possible gender differences, the influence of test order, and correlation of test results.

RESULTS

The time required for the adaptive Freiburg monosyllabic speech test was significantly higher than for the Oldenburg sentence test. No significant impact of gender or test order could be shown. The mean signal-to-noise ratio for 50% speech discrimination of the Oldenburg sentence test was significantly smaller than for the adaptive Freiburg monosyllabic speech test. No correlation could be shown between the results of the two tests CONCLUSION: The Freiburg monosyllabic test can not only be used for quantifying discrimination loss in percentage terms, but also to measure the 50% speech recognition threshold with an adaptive algorithm. However, the procedure of the adaptive Freiburg monosyllabic test is more time consuming than that of the Oldenburg sentence test. Concerning a possible missing correlation between the results for 50% speech discrimination, further studies with hearing-impaired persons are needed.

[Speech audiometry and data logging in CI patients : Implications for adequate test levels. German version]

BACKGROUND

As part of postoperative cochlear implant (CI) diagnostics, speech comprehension tests are performed to monitor audiological outcome. In recent years, a trend toward improved suprathreshold speech intelligibility in quiet and an extension of intelligibility to softer sounds has been observed. Parallel to audiometric data, analysis of the patients' acoustic environment can take place by means of data logging in modern CI systems.

OBJECTIVES

Which test levels reflect the individual listening environment in a relevant manner and how can these be reflected in a clinical audiometric setting?

PATIENTS AND METHODS

In a retrospective analysis, data logs of 263 adult CI patients were evaluated for sound level and the listening situation (quiet, speech in quiet, noise, speech in noise, music, and wind). Additionally, monosyllabic word comprehension in quiet was analyzed in experienced CI users at presentation levels of 40-80 dB.

RESULTS

For the sound level in the acoustic environment of postlingually deafened adult CI users, data logging shows a maximum occurrence of speech signals in the range 50-59 dB. This demonstrates the relevance of everyday speech comprehension at levels below 60 dB.

CONCLUSIONS

Individual optimization of speech intelligibility with a CI speech processor should not be performed in the range of 65-70 dB only, but also at lower levels. Measurements at 50 dB currently seem to be a useful addition.

Current audiological diagnostics

Today's audiological functional diagnostics is based on a variety of hearing tests, whose large number takes account of the variety of malfunctions of a complex sensory organ system and the necessity to examine it in a differentiated manner and at any age of life. The objective is to identify nature and origin of the hearing loss and to quantify its extent as far as necessary to dispose of the information needed to initiate the adequate medical (conservative or operational) treatment or the provision with technical hearing aids or prostheses. Moreover, audiometry provides the basis for the assessment of impairment and handicap as well as for the calculation of the degree of disability. In the present overview, the current state of the method inventory available for practical use is described, starting from basic diagnostics over to complex special techniques. The presentation is systematically grouped in subjective procedures, based on psychoacoustic exploration, and objective methods, based on physical measurements: preliminary hearing tests, pure tone threshold, suprathreshold processing of sound intensity, directional hearing, speech understanding in quiet and in noise, dichotic hearing, tympanogram, acoustic reflex, otoacoustic emissions and auditory evoked potentials. Apart from a few still existing gaps, this method inventory covers the whole spectrum of all clinically relevant functional deficits of the auditory system.

[Examination of a training effect in the Freiburg monosyllabic test]

BACKGROUND

The Freiburg monosyllabic test (FBE) was introduced into clinical routine almost 60 years ago. Recently, there has been renewed scientific interest in the FBE. Nevertheless, neither the earlier nor the later publications showed any evidence for a training effect. For this reason, this aspect is examined in more detail in the present study.

METHODOLOGY

All 20 test lists of the FBE were presented in a fixed, predetermined order to 40 suitable otologically normal subjects. According to DIN 45626-1, the 50 % speech discrimination score is expected at a level of 29.3 dB SPL (Sound Pressure Level). In this study, the test material was presented at a level of 29 dB SPL. The speech discrimination scores were analyzed depending on the particular test run.

RESULTS

The mean speech recognition score (43.2 %) depended on the test run. An increase in speech recognition by 13 percent points was observed in the first three test runs. After two test runs, no further increase in speech recognition was observed.

CONCLUSION

When using the FBE in clinical routine, two test lists should be heard by the patients before the actual test starts. This procedure helps to improve the quality of the FBE.

[Phonemic balance of the Freiburg monosyllabic speech test]

BACKGROUND

ISO 8253-3 [4] describes the requirements for speech tests with respect to their phonemic balance. The fulfillment of these requirements by the Freiburg monosyllabic speech test were examined.

METHODS

The Freiburg monosyllables were phonologically transcribed and analyzed with respect to their structural types, vowels and consonants, as well as phonological classes, and compared to reference values.

RESULTS

The phonemic distribution of the Freiburg monosyllables differs slightly from the reference values for the German language. The differences are presumably related to the restriction to monosyllabic substantives. Most test lists (except for 12) contain similar proportions of different phonem classes for vowel and consonants according to Hahlbrock and ISO 8253-3 [4].

CONCLUSION

The deviations of test lists 5, 11, and 15 in a study for perceptual equivalence cannot be explained by phonemic imbalance in comparison to other test lists. Only the lower recognition rates for test list 12 might be explained by its deviant phonemic distribution.

[The Freiburg speech intelligibility test : A pillar of speech audiometry in German-speaking countries]

The Freiburg speech intelligibility test according to DIN 45621 was introduced around 60 years ago. For decades, and still today, the Freiburg test has been a standard whose relevance extends far beyond pure audiometry. It is used primarily to determine the speech perception threshold (based on two-digit numbers) and the ability to discriminate speech at suprathreshold presentation levels (based on monosyllabic nouns). Moreover, it is a measure of the degree of disability, the requirement for and success of technical hearing aids (auxiliaries directives), and the compensation for disability and handicap (Königstein recommendation). In differential audiological diagnostics, the Freiburg test contributes to the distinction between low- and high-frequency hearing loss, as well as to identification of conductive, sensory, neural, and central disorders. Currently, the phonemic and perceptual balance of the monosyllabic test lists is subject to critical discussions. Obvious deficiencies exist for testing speech recognition in noise. In this respect, alternatives such as sentence or rhyme tests in closed-answer inventories are discussed.

[Use of Freiburg monosyllabic test words in the contemporary German language : Currentness of the test words]

The Freiburg monosyllabic test has a word inventory based on the word frequency in written sources from the 19th century, the distribution of which is not even between the test lists. The median distributions of word frequency ranking in contemporary language of nine test lists deviate significantly from the overall median of all 400 monosyllables. Lists 1, 6, 9, 10, and 17 include significantly more very rarely used words; lists 2, 3, 5, and 15, include significantly more very frequently used words. Compared with the word frequency in the contemporary spoken German language, about 45 % of the test words are practically no longer used. Due to this high proportion of extremely rarely or no longer used words, the word inventory is no longer representative of the contemporary German language-neither for the written, nor for the spoken language. Highly educated persons with a large vocabulary are thereby favored. The reference values for normal-hearing persons should therefore be reevaluated.

[Test-retest reliability of the Freiburg monosyllabic speech test]

BACKGROUND

ISO 8253-3 describes the requirements for speech tests used in audiology. One aspect is the test-retest reliability, which was here examined for the Freiburg monosyllabic speech test.

METHODS

Speech recognition scores were examined for 30 listeners with normal hearing ability. All 20 lists of the Freiburg monosyllabic speech test were tested at four different presentation levels. The retest was carried out 7-9 months later.

RESULTS

The test-retest reliability of the Freiburg monosyllabic speech test in this study is between 13 percentage points for a speech recognition score of 95 %, and 24 percentage points for a speech recognition score of 39 %. The measurement accuracy can be estimated using binomial distribution.

CONCLUSION

The reproducibility of the results is limited by the small number of test items (20 words) in each list. This does not fulfill the requirements for speech tests in diagnostics and rehabilitation. An improvement of the test-retest reliability can be achieved using several test lists.