Inga Holube

Measures of speech intelligibility in noise show limited correspondence with difficulties people with hearing loss report from daily life. This mismatch suggests that standard measurement conditions do not sufficiently capture aspects that are relevant for speech perception, such as dip listening and spatial release from masking. In the present study we developed and evaluated a test condition that incorporates these aspects and compared it with a standard condition. Speech intelligibility was measured in 100 participants with normal hearing (NH, N=17) and hearing loss (HL, N=83) ranging from mild to severe. Measurements were conducted using the German matrix sentence test (OLSA) in the standard condition with frontal presentation of stationary noise co-located with the target speech, and the proposed condition with fluctuating, speech-like maskers spatially separated (±60°) from the target. Stimuli were presented via headphones using virtual acoustics. Tests were performed unaided and with individualized amplification. The proposed condition revealed reduced speech intelligibility also for listeners with HL that showed close-to-normal speech intelligibility in the standard condition. With individualized amplification, more listeners with HL showed reduced speech intelligibility compared to NH listeners than in the standard condition. Benefit of amplification varied widely across individuals with similar hearing thresholds, with some listeners showing little or no benefit. The advantages of the proposed condition were driven by masker fluctuations rather than by spatial separation of sound sources. These findings demonstrate that speech intelligibility measurements incorporating fluctuating maskers provide potentially relevant information beyond standard assessments and can support a more individualized assessment of hearing loss.

Ecological Momentary Assessment (EMA) is a timely method for capturing differences between hearing aids (HAs) or HA features in real-world environments. Studies vary greatly in reporting periods, specifically how long ago an event can have occurred to still be reported and how events are selected when not summarizing over a period of time. The potential effects of different reporting periods on HA or HA feature contrast remain unexplored. In a 14-day EMA study, 22 hearing-aid users assessed both a basic and an advanced HA program, which were switched daily without participant control. Several times daily, participants used a smartphone app to report on satisfaction with the HA program, overall listening experience, sound quality, and listening effort. The app had participants focus on the current situation, denoting a momentary reporting period, and the worst listening experience within the previous 30 min, denoting a short-term retrospective period. Participants also completed an end-of-day questionnaire. Sound-pressure levels and HA classifier data were recorded continuously. Mixed modeling was used to examine the impact of reporting periods on ratings. Main findings showed no rating differences between the two HA programs in momentary or end-of-day assessments. However, differences emerged in short-term retrospective reporting, thus in the assessments of the worst experience within the preceding 30 min. Various time effects were also observed. Depending on the reporting period, the analysis of sound-pressure levels and HA classifier data revealed variations in real-world snapshots. In conclusion, this study underscores the need to diligently define reporting periods in hearing-related EMA research.

Speech recognition scores in noise can be affected by measurement conditions such as the spatial configuration, room acoustic properties, or the position and head orientation of a test person. This is critical when comparing repeated measurements, e.g., during hearing aid verification. While the basic effects of these factors are known, specific effect sizes for practically relevant configurations have not previously been reported. We investigated the effects of audiological test-room acoustics with low reverberation, and of head movements on speech-in-noise tests for typical spatial configurations. Speech-recognition thresholds (SRTs) and head movements were measured in 240 normal-hearing participants in six rooms for five loudspeaker configurations (S₀N₀, S₀N_±45, S₀N_±90, S₀N₁₈₀ and S_±45N_∓45). Additionally, head positions were reproduced with an artificial head, and using a binaural speech intelligibility model, binaural room impulse responses were measured to estimate the influence of head movements on the SRT. The results show that the effects of room acoustic properties and head movements varies greatly between spatial configurations. Head rotations around the vertical axis can affect speech recognition scores by up to 8 dB, most critically for the configuration S₀N₁₈₀. For spatially separated sound sources, different room acoustic conditions caused differences in SRT of up to 5 dB.

In speech audiometry, the speech-recognition threshold (SRT) is usually established by adjusting the signal-to-noise ratio (SNR) until 50% of the words or sentences are repeated correctly. However, these conditions are rarely encountered in everyday situations. Therefore, for a group of 15 young participants with normal hearing and a group of 12 older participants with hearing impairment, speech-recognition scores were determined at SRT and at four higher SNRs using several stationary and fluctuating maskers. Participants’ verbal responses were recorded, and participants were asked to self-report their listening effort on a categorical scale (self-reported listening effort, SR-LE). The responses were analyzed using an Automatic Speech Recognizer (ASR) and compared to the results of a human examiner. An intraclass correlation coefficient of r = .993 for the agreement between their corresponding speech-recognition scores was observed. As expected, speech-recognition scores increased with increasing SNR and decreased with increasing SR-LE. However, differences between speech-recognition scores for fluctuating and stationary maskers were observed as a function of SNR, but not as a function of SR-LE. The verbal response time (VRT) and the response speech rate (RSR) of the listeners’ responses were measured using an ASR. The participants with hearing impairment showed significantly lower RSRs and higher VRTs compared to the participants with normal hearing. These differences may be attributed to differences in age, hearing, or both. With increasing SR-LE, VRT increased and RSR decreased. The results show the possibility of deriving a behavioral measure, VRT, measured directly from participants’ verbal responses during speech audiometry, as a proxy for SR-LE.

Speech-recognition tests are widely used in both clinical and research audiology. The purpose of this study was the development of a novel speech-recognition test that combines concepts of different speech-recognition tests to reduce training effects and allows for a large set of speech material. The new test consists of four different words per trial in a meaningful construct with a fixed structure, the so-called phrases. Various free databases were used to select the words and to determine their frequency. Highly frequent nouns were grouped into thematic categories and combined with related adjectives and infinitives. After discarding inappropriate and unnatural combinations, and eliminating duplications of (sub-)phrases, a total number of 772 phrases remained. Subsequently, the phrases were synthesized using a text-to-speech system. The synthesis significantly reduces the effort compared to recordings with a real speaker. After excluding outliers, measured speech-recognition scores for the phrases with 31 normal-hearing participants at fixed signal-to-noise ratios (SNR) revealed speech-recognition thresholds (SRT) for each phrase varying up to 4 dB. The median SRT was −9.1 dB SNR and thus comparable to existing sentence tests. The psychometric function's slope of 15 percentage points per dB is also comparable and enables efficient use in audiology. Summarizing, the principle of creating speech material in a modular system has many potential applications.

Common methods to assess hearing deficits and the benefit of hearing devices include retrospective questionnaires and speech tests under controlled conditions. As typically applied, both approaches suffer from serious limitations regarding their ecological validity. An alternative approach rapidly gaining widespread use is ecological momentary assessment (EMA), which employs repeated assessments of individual everyday situations. Smartphones facilitate the implementation of questionnaires and rating schemes to be administered in the real life of study participants or customers, during or shortly after an experience. In addition, objective acoustical parameters extracted from head- or body-worn microphones and/or settings from the hearing aid’s signal processing unit can be stored alongside the questionnaire data. The advantages of using EMA include participant-specific, context-sensitive information on activities, experienced challenges, and preferences. However, to preserve the privacy of all communication partners and bystanders, the law in many countries does not allow audio recordings, limiting the information about environmental acoustics to statistical data such as, for example, levels and averaged spectra. Other challenges for EMA are, for example, the unsupervised handling of the equipment, the trade-off between the accuracy of description and the number of similar listening situations when performing comparisons (e.g., with and without hearing aids), the trade-off between the duration of recording intervals and the amount of data collected and analyzed, the random or target-oriented reminder for subjective responses, as well as the willingness and ability of the participants to respond while doing specific tasks. This contribution reviews EMA in hearing research, its purpose, current applications, and possible future directions.

Hintergrund Während eine mit dem Alter zunehmende Schwerhörigkeit im Hochtonbereich hinreichend belegt ist, sind das Ausmaß und die Zunahme möglicher Schwerhörigkeiten bei jungen Menschen weiterhin unklar. Da in diesem Altersbereich ein hoher Anteil an Normalhörigkeit zu erwarten ist, sind die Anforderungen an Screening-Methoden besonders hoch und die Motivation zur Teilnahme eher niedrig. Die verpflichtende Musterung umfasst u. a. eine audiologische Hörprüfung (Tonaudiogramm) und bietet daher die Möglichkeit das Hörvermögen junger männlicher Erwachsener zu analysieren. Material und Methoden Die Prävalenz für Hörbeeinträchtigungen wurde anhand der Luftleitungshörschwellen 18- bis 20-jähriger Männer von 54 deutschen Kreiswehrersatzämtern (KWEA) der Jahre 2008–2010 bestimmt. Als Kriterium wurde die Überschreitung einer Hörschwelle von 20 dB HL bei mindestens einer der Frequenzen 3, 4 oder 6 kHz auf mindestens einem Ohr verwendet. Diesem sehr strengen Kriterium wurden andere Definitionen für Hörschäden vergleichend gegenübergestellt. Ergebnisse Die Prävalenz von relevanten Hörschäden beträgt im Mittel 15,3 % und liegt damit im Bereich anderer Untersuchungen. Die Ergebnisse einzelner KWEA unterscheiden sich jedoch um bis zu einem Faktor 10. Schlussfolgerung Aufgrund stark schwankender Messqualität in den KWEA lässt sich nicht klären, ob regionale Unterschiede im Hörvermögen junger Männer bestehen und ob sich dieses im Vergleich zu früheren Untersuchungen verschlechtert hat. Die hohe Variabilität bei Messungen nahe der Hörschwelle erfordert eine ständige Qualitätskontrolle. Dabei können die Hörergebnisse im Screening nicht nach den strengen Kriterien bewertet werden, die für Hörprüfungen in audiologischen Zentren oder Studien anzusetzen sind. Objective High-frequency hearing loss is known to increase with age, whereas the amount and rate of increase of hearing loss in younger people is still unclear. A large proportion of young age groups is expected to preserve normal hearing. Therefore, the requirements for screening methods are parti­cularly high and the motivation to participate is low. The obligatory examinations preceding military conscription include a pure-tone audiogram and thus allow the analysis of the hearing status of young male adults. Material and Methods The prevalence of hearing impairment was determined using air-conduction thresholds of 18- to 20-year old men, from 54 German registration offices (KWEA), measured in 2008 to 2010. The criterion was based on candidates exceeding a threshold of 20 dB HL for one of the frequencies 3, 4, or 6 kHz in at least one ear. This very strict criterion was compared to other definitions of hearing impairment. Results The prevalence of hearing impairment was, on average, 15.3 % and thus in the same range as in other studies. However, the results of single KWEA differed by up to a factor of 10. Conclusions Due to high fluctuations in measurement quality in the KWEA, regional differences in hearing thresholds of young men are not resolvable and it remains unclear whether the hearing loss has increased in comparison to earlier studies. The high variability of measurements near thresholds requires permanent quality inspections. However, hearing thresholds derived from screening cannot be evaluated applying the same criteria as for hearing tests in audiological centers or studies.

Noise and reverberation affect speech intelligibility and increase listening effort. The impact is more severe for hearing-impaired listeners than for normal-hearing listeners and might lead to less social interactions, and reduced quality of life. While lab experiments are well controlled to get reliable outcomes, every-day listening situations are far more complex. Obtaining objective data of acoustical characteristics outside a laboratory is difficult, given the required equipment and its proper handling as well as privacy concerns emerging from audio recordings in a non-regulated and populated environment. Therefore, we developed a privacy-aware smartphone-based system that allows for long-term ecological momentary assessment. This system combines descriptions of the environment and subjective ratings on predefined scales with objective features derived from the acoustical signal. In a field study, forty-seven elderly listeners used the system for about four consecutive days. Results show that the listeners spend most of their time in environments with quite high signal-to-noise ratios resulting in high speech intelligibility ratings and low listening effort. More demanding situations are comparatively rare and include restaurant or car environments. The presentation summarizes the study results and discusses their contribution to further developments of today’s lab experiments towards more natural listening settings.