Markus Landwehr

The perception of prosody and speaker gender in normal-hearing listeners and cochlear implant recipients

The purpose of this study was to examine the effects of altering the fundamental frequency (F0) on perception of prosody and speaker gender in both normal-hearing listeners and cochlear implant (CI) recipients. Tests with natural speech and defined modifications of the F0 were performed, and the resulting changes in perception were measured. Compared to the normal-hearing listeners, most of the CI users exhibited worse outcomes, especially for sentence stress. In contrast, the speaker gender tests yielded similar results for both groups when artificially modifying the F0 contour. The results seemed to be strongly related to the duration of alterations in F0. Although the perception of prosodic cues was limited in most of the CI recipients, they showed qualitatively similar results to normal-hearing listeners in that the boundary between questions and statements and between female and male voices was comparable. A large inter-individual difference in performance was observed among the CI recipients, which could not be attributed to different processor or implant types or to other factors such as implant experience.

Untersuchungen zum Sprachverstehen und zu kognitiven Fähigkeiten im Alter

ZusammenfassungHintergrundÄltere Personen berichten häufig über Probleme beim Sprachverstehen, insbesondere in komplexen Kommunikationssituationen. Neben Hörstörungen können hierbei Einschränkungen kognitiver Leistungen eine Rolle spielen.MethodenMit 12 normalhörenden jüngeren Personen und 14 älteren Personen mit besonders gutem Hörvermögen wurden Sprachverständlichkeitsmessungen in unterschiedlich komplexen akustischen Situationen durchgeführt. Zur Beurteilung der kognitiven Fähigkeiten kamen verschiedene neuropsychologische Tests zum Einsatz.ErgebnisseDie älteren Probanden wiesen trotz vergleichbaren tonaudiometrischen Befunden in fast allen Messungen schlechtere Sprachverständlichkeitsergebnisse auf als die jüngeren Personen. Besonders große Unterschiede zeigten sich bei Verwendung von fluktuierenden Maskierern und konkurrierenden Sprechern. Es ergaben sich signifikante Korrelationen zu Befunden eines neuropsychologischen Tests, welcher das deklarative Verbalgedächtnis erfasst.SchlussfolgerungÄltere Personen weisen in komplexen akustischen Situationen schlechteres Sprachverstehen als jüngere Personen auf. Unterschiede im Sprachverstehen sind teilweise auf kognitive Leistungen zurückzuführen. Insbesondere das Arbeitsgedächtnis scheint eine wichtige Rolle zu spielen.AbstractBackgroundElderly persons frequently complain about problems with speech understanding especially in complex acoustic situations. Besides hearing impairment the decline of cognitive functions might explain these problems.MethodsIn 12 normal hearing young subjects and 14 elderly listeners with extraordinarily good hearing speech perception was measured in a broad range of different acoustic situations. Cognitive functioning was evaluated with different neuropsychological tests.ResultsDespite comparable pure tone thresholds the elderly listeners revealed worse speech discrimination than the young subjects in almost all test situations. Largest differences were found in situations with fluctuating maskers and competing talkers. Most of the speech perception results revealed significant correlations with the outcome from a neuropsychological test addressing declarative verbal memory.ConclusionsIn complex listening situations elderly persons reveal worse speech understanding than younger subjects. Differences in speech perception can partly be attributed to cognitive abilities. In particular, working memory seems to be an important factor.BACKGROUND Elderly persons frequently complain about problems with speech understanding especially in complex acoustic situations. Besides hearing impairment the decline of cognitive functions might explain these problems. METHODS In 12 normal hearing young subjects and 14 elderly listeners with extraordinarily good hearing speech perception was measured in a broad range of different acoustic situations. Cognitive functioning was evaluated with different neuropsychological tests. RESULTS Despite comparable pure tone thresholds the elderly listeners revealed worse speech discrimination than the young subjects in almost all test situations. Largest differences were found in situations with fluctuating maskers and competing talkers. Most of the speech perception results revealed significant correlations with the outcome from a neuropsychological test addressing declarative verbal memory. CONCLUSIONS In complex listening situations elderly persons reveal worse speech understanding than younger subjects. Differences in speech perception can partly be attributed to cognitive abilities. In particular, working memory seems to be an important factor.

Effects of various electrode configurations on music perception, intonation and speaker gender identification

Abstract Advances in speech coding strategies and electrode array designs for cochlear implants (CIs) predominantly aim at improving speech perception. Current efforts are also directed at transmitting appropriate cues of the fundamental frequency (F0) to the auditory nerve with respect to speech quality, prosody, and music perception. The aim of this study was to examine the effects of various electrode configurations and coding strategies on speech intonation identification, speaker gender identification, and music quality rating. In six MED-EL CI users electrodes were selectively deactivated in order to simulate different insertion depths and inter-electrode distances when using the high definition continuous interleaved sampling (HDCIS) and fine structure processing (FSP) speech coding strategies. Identification of intonation and speaker gender was determined and music quality rating was assessed. For intonation identification HDCIS was robust against the different electrode configurations, whereas fine structure processing showed significantly worse results when a short electrode depth was simulated. In contrast, speaker gender recognition was not affected by electrode configuration or speech coding strategy. Music quality rating was sensitive to electrode configuration. In conclusion, the three experiments revealed different outcomes, even though they all addressed the reception of F0 cues. Rapid changes in F0, as seen with intonation, were the most sensitive to electrode configurations and coding strategies. In contrast, electrode configurations and coding strategies did not show large effects when F0 information was available over a longer time period, as seen with speaker gender. Music quality relies on additional spectral cues other than F0, and was poorest when a shallow insertion was simulated.

Untersuchungen zum "Informational Masking" bei Kochleaimplantat-Nutzern

BACKGROUND Informational masking (IM) refers to the problem of understanding target speech in the simultaneous presence of a masking speech signal. The adverse effects are attributable to the additional information provided by the competing talker. Cochlear implant (CI) recipients are not able to understand speech satisfactorily in situations such as these. The aim of the present study is to examine the extent to which CI recipients are able to use differences between the speakers with respect to level (target-to-masker ratio, TMR) and fundamental frequency (f0) in order to improve speech intelligibility. SUBJECTS AND METHODS Target (TS) and masker sentences (MS) were selected from the Oldenburg Sentence Test (OlSa) and were modified and superimposed. The TS were explicitly labelled using a keyword. The MS were changed with respect to TMR and f0. The TS intelligibility of different modifications was measured in six post-lingually deafened CI recipients and six normal listeners (NL). RESULTS The NL revealed speech understanding close to 100% even for small differences in f0 of 40 Hz or level differences of 5 dB. In CI recipients, a significant change in intelligibility could only be demonstrated with increased TMR, but not with differences in f0. CONCLUSIONS In CI recipients, IM cannot be reduced by means of differences in f0 between the competing talkers, but only by level differences. This might be explained by the restricted spectral resolution and the insufficient transmission of f0 in CIs. Adverse effects in NL can predominantly be attributed to IM, while additional masking effects take place in CI recipients.

Konzeption und Realisierung einer Prosodie-Testbatterie

BACKGROUND Prosody reflects rhythmic and melodic aspects in speech and is one of the quality measures that shows--apart from pure speech understanding--a rising interest in the assessment of technical hearing aids, especially of cochlear implants. At present, there is no adequate test battery for the German speaking population. The test battery presented in this study aims to fill this gap. METHODS The test battery consists of four different modules addressing different prosodic cues, namely duration, question vs statement, sentence stress, and speaker gender. One part of the test battery aims at reflecting everyday situations and was realized with six different speakers representing various pitch frequencies and speak rates. Another goal of the tests is to detect very small differences in prosody perception. Therefore, natural utterances were artificially modified by changing the underlying acoustic parameters (e.g. duration, fundamental frequency). Measurements were performed with 12 normal listeners in order to investigate the properties of the tests. RESULTS As expected, the normal listeners revealed discrimination rates of close to 100% in that part of the test battery using natural utterances. For the part with the modified stimuli, all four modules revealed very steep discrimination functions indicating that the normal listeners were able to use very small changes in the acoustic parameters as cues for prosody perception. Moreover, the slope of the discrimination function revealed very low variability. CONCLUSIONS Together with preliminary data from cochlear implant recipients who clearly showed different psychometric functions, the test battery seems suitable for a comprehensive evaluation of prosody perception. This facilitates future examinations of speech processing beyond the pure understanding of speech.

Examination of spectral timbre cues and musical instrument identification in cochlear implant recipients

Abstract Objectives To investigate the discrimination of two isolated spectral timbre cues, spectral centroid (Fc) and spectral irregularity (spIrr), in cochlear implant (CI) listeners. To examine whether the perception of Fc and spIrr changes is related to the perception of loudness and pitch and the identification of musical instruments. Methods Stimuli were based on French horn recordings which were artificially manipulated with respect to isolated changes in Fc and spIrr. Difference limens for Fc and spIrr were determined and changes in loudness and pitch perception based on these modifications were examined. Identification of musical instruments was additionally assessed. Results Mean difference limens were 161 Hz for Fc and 0.63 dB for spIrr. Modifications in spectral timbre cues caused changes in loudness and pitch perception. None of the timbre cues examined showed a significant correlation with musical instrument identification. In contrast, instrument identification was significantly related to the frequency of listening to music prior to onset of deafness. Conclusions CI recipients are able to detect small modifications in spectral timbre cues which are in turn associated with changes in loudness and pitch. Variations of spectral centroid have a larger impact on loudness and pitch perception than variations of spectral irregularity. Music listening behaviour prior to onset of deafness is significantly associated with musical instrument identification.

Untersuchungen zum „Informational Masking“ bei Kochleaimplantat-Nutzern@@@Examining informational masking in cochlear implant users

BACKGROUND Informational masking (IM) refers to the problem of understanding target speech in the simultaneous presence of a masking speech signal. The adverse effects are attributable to the additional information provided by the competing talker. Cochlear implant (CI) recipients are not able to understand speech satisfactorily in situations such as these. The aim of the present study is to examine the extent to which CI recipients are able to use differences between the speakers with respect to level (target-to-masker ratio, TMR) and fundamental frequency (f0) in order to improve speech intelligibility. SUBJECTS AND METHODS Target (TS) and masker sentences (MS) were selected from the Oldenburg Sentence Test (OlSa) and were modified and superimposed. The TS were explicitly labelled using a keyword. The MS were changed with respect to TMR and f0. The TS intelligibility of different modifications was measured in six post-lingually deafened CI recipients and six normal listeners (NL). RESULTS The NL revealed speech understanding close to 100% even for small differences in f0 of 40 Hz or level differences of 5 dB. In CI recipients, a significant change in intelligibility could only be demonstrated with increased TMR, but not with differences in f0. CONCLUSIONS In CI recipients, IM cannot be reduced by means of differences in f0 between the competing talkers, but only by level differences. This might be explained by the restricted spectral resolution and the insufficient transmission of f0 in CIs. Adverse effects in NL can predominantly be attributed to IM, while additional masking effects take place in CI recipients.

Konzeption und Realisierung einer Prosodie-Testbatterie@@@Conception and realisation of a prosody test battery

BACKGROUND Prosody reflects rhythmic and melodic aspects in speech and is one of the quality measures that shows--apart from pure speech understanding--a rising interest in the assessment of technical hearing aids, especially of cochlear implants. At present, there is no adequate test battery for the German speaking population. The test battery presented in this study aims to fill this gap. METHODS The test battery consists of four different modules addressing different prosodic cues, namely duration, question vs statement, sentence stress, and speaker gender. One part of the test battery aims at reflecting everyday situations and was realized with six different speakers representing various pitch frequencies and speak rates. Another goal of the tests is to detect very small differences in prosody perception. Therefore, natural utterances were artificially modified by changing the underlying acoustic parameters (e.g. duration, fundamental frequency). Measurements were performed with 12 normal listeners in order to investigate the properties of the tests. RESULTS As expected, the normal listeners revealed discrimination rates of close to 100% in that part of the test battery using natural utterances. For the part with the modified stimuli, all four modules revealed very steep discrimination functions indicating that the normal listeners were able to use very small changes in the acoustic parameters as cues for prosody perception. Moreover, the slope of the discrimination function revealed very low variability. CONCLUSIONS Together with preliminary data from cochlear implant recipients who clearly showed different psychometric functions, the test battery seems suitable for a comprehensive evaluation of prosody perception. This facilitates future examinations of speech processing beyond the pure understanding of speech.

Untersuchungen zum Sprachverstehen und zu kognitiven Fähigkeiten im Alter@@@Examination of speech perception and cognitive functioning in the elderly

ZusammenfassungHintergrundÄltere Personen berichten häufig über Probleme beim Sprachverstehen, insbesondere in komplexen Kommunikationssituationen. Neben Hörstörungen können hierbei Einschränkungen kognitiver Leistungen eine Rolle spielen.MethodenMit 12 normalhörenden jüngeren Personen und 14 älteren Personen mit besonders gutem Hörvermögen wurden Sprachverständlichkeitsmessungen in unterschiedlich komplexen akustischen Situationen durchgeführt. Zur Beurteilung der kognitiven Fähigkeiten kamen verschiedene neuropsychologische Tests zum Einsatz.ErgebnisseDie älteren Probanden wiesen trotz vergleichbaren tonaudiometrischen Befunden in fast allen Messungen schlechtere Sprachverständlichkeitsergebnisse auf als die jüngeren Personen. Besonders große Unterschiede zeigten sich bei Verwendung von fluktuierenden Maskierern und konkurrierenden Sprechern. Es ergaben sich signifikante Korrelationen zu Befunden eines neuropsychologischen Tests, welcher das deklarative Verbalgedächtnis erfasst.SchlussfolgerungÄltere Personen weisen in komplexen akustischen Situationen schlechteres Sprachverstehen als jüngere Personen auf. Unterschiede im Sprachverstehen sind teilweise auf kognitive Leistungen zurückzuführen. Insbesondere das Arbeitsgedächtnis scheint eine wichtige Rolle zu spielen.AbstractBackgroundElderly persons frequently complain about problems with speech understanding especially in complex acoustic situations. Besides hearing impairment the decline of cognitive functions might explain these problems.MethodsIn 12 normal hearing young subjects and 14 elderly listeners with extraordinarily good hearing speech perception was measured in a broad range of different acoustic situations. Cognitive functioning was evaluated with different neuropsychological tests.ResultsDespite comparable pure tone thresholds the elderly listeners revealed worse speech discrimination than the young subjects in almost all test situations. Largest differences were found in situations with fluctuating maskers and competing talkers. Most of the speech perception results revealed significant correlations with the outcome from a neuropsychological test addressing declarative verbal memory.ConclusionsIn complex listening situations elderly persons reveal worse speech understanding than younger subjects. Differences in speech perception can partly be attributed to cognitive abilities. In particular, working memory seems to be an important factor.BACKGROUND Elderly persons frequently complain about problems with speech understanding especially in complex acoustic situations. Besides hearing impairment the decline of cognitive functions might explain these problems. METHODS In 12 normal hearing young subjects and 14 elderly listeners with extraordinarily good hearing speech perception was measured in a broad range of different acoustic situations. Cognitive functioning was evaluated with different neuropsychological tests. RESULTS Despite comparable pure tone thresholds the elderly listeners revealed worse speech discrimination than the young subjects in almost all test situations. Largest differences were found in situations with fluctuating maskers and competing talkers. Most of the speech perception results revealed significant correlations with the outcome from a neuropsychological test addressing declarative verbal memory. CONCLUSIONS In complex listening situations elderly persons reveal worse speech understanding than younger subjects. Differences in speech perception can partly be attributed to cognitive abilities. In particular, working memory seems to be an important factor.