Measuring open-set, word recognition in school-aged children: Corpus of monosyllabic target words and speech maskers.

A corpus of stimuli has been collected to support the use of common materials across research laboratories to examine school-aged children's word recognition in speech maskers. The corpus includes (1) 773 monosyllabic words that are known to be in the lexicon of 5- and 6-year-olds and (2) seven masker passages that are based on a first-grade child's writing samples. Materials were recorded by a total of 13 talkers (8 women; 5 men). All talkers recorded two masker passages; 3 talkers (2 women; 1 man) also recorded the target words. The annotated corpus is freely available online for research purposes.

Individual differences in the attentional modulation of the human auditory brainstem response to speech inform on speech-in-noise deficits.

People with normal hearing thresholds can nonetheless have difficulty with understanding speech in noisy backgrounds. The origins of such supra-threshold hearing deficits remain largely unclear. Previously we showed that the auditory brainstem response to running speech is modulated by selective attention, evidencing a subcortical mechanism that contributes to speech-in-noise comprehension. We observed, however, significant variation in the magnitude of the brainstem's attentional modulation between the different volunteers. Here we show that this variability relates to the ability of the subjects to understand speech in background noise. In particular, we assessed 43 young human volunteers with normal hearing thresholds for their speech-in-noise comprehension. We also recorded their auditory brainstem responses to running speech when selectively attending to one of two competing voices. To control for potential peripheral hearing deficits, and in particular for cochlear synaptopathy, we further assessed noise exposure, the temporal sensitivity threshold, the middle-ear muscle reflex, and the auditory-brainstem response to clicks in various levels of background noise. These tests did not show evidence for cochlear synaptopathy amongst the volunteers. Furthermore, we found that only the attentional modulation of the brainstem response to speech was significantly related to speech-in-noise comprehension. Our results therefore evidence an impact of top-down modulation of brainstem activity on the variability in speech-in-noise comprehension amongst the subjects.

Vibro-Tactile Enhancement of Speech Intelligibility in Multi-talker Noise for Simulated Cochlear Implant Listening.

Many cochlear implant (CI) users achieve excellent speech understanding in acoustically quiet conditions but most perform poorly in the presence of background noise. An important contributor to this poor speech-in-noise performance is the limited transmission of low-frequency sound information through CIs. Recent work has suggested that tactile presentation of this low-frequency sound information could be used to improve speech-in-noise performance for CI users. Building on this work, we investigated whether vibro-tactile stimulation can improve speech intelligibility in multi-talker noise. The signal used for tactile stimulation was derived from the speech-in-noise using a computationally inexpensive algorithm. Eight normal-hearing participants listened to CI simulated speech-in-noise both with and without concurrent tactile stimulation of their fingertip. Participants' speech recognition performance was assessed before and after a training regime, which took place over 3 consecutive days and totaled around 30 min of exposure to CI-simulated speech-in-noise with concurrent tactile stimulation. Tactile stimulation was found to improve the intelligibility of speech in multi-talker noise, and this improvement was found to increase in size after training. Presentation of such tactile stimulation could be achieved by a compact, portable device and offer an inexpensive and noninvasive means for improving speech-in-noise performance in CI users.

Assessment of speech recognition abilities in quiet and in noise: a comparison between self-administered home testing and testing in the clinic for adult cochlear implant users.

Self speech recognition tests in quiet and noise at home are compared to the standard tests performed in the clinic. Potential effects of stimuli presentation modes (loudspeaker or audio cable) and assessment (clinician or self-assessment at home) on test results were investigated. Speech recognition in quiet was assessed using the standard Dutch test with monosyllabic words. Speech recognition in noise was assessed with the digits-in-noise test. Sixteen experienced CI users (aged between 44 and 83 years) participated. No significant difference was observed in speech recognition in quiet between and presentation modes. Speech recognition in noise was significantly better with the audio cable than with the loudspeaker. There was no significant difference in speech recognition in quiet at 65 dB and in speech recognition in noise between self-assessment at home and testing in the clinic. At 55 dB, speech recognition assessed at home was slightly but significantly better than that assessed in the clinic. The results demonstrate that it is feasible for experienced CI users to perform self-administered speech recognition tests at home. Self-assessment by CI users of speech recognition in quiet and noise within the home environment could serve as an alternative to the tests performed in the clinic.

LiCoS: A New Linguistically Controlled Sentences Test to Assess Functional Hearing Performance.

PURPOSE: To overcome the potential tension between clinical and ecological validity in speech audiometric assessment by creating a new set of sentence materials with high linguistic validity for the Dutch-speaking area. METHODS: A linguistic "fingerprint" of modern spoken Dutch and Flemish served to generate a set of sentences recorded from 1 male and 1 female talker. The sentences were presented to 30 normal-hearing listeners in stationary speech noise at a signal-to-noise ratio (SNR) of -5 dB sound pressure level (SPL). A list design criterion was used to achieve perceptive homogeneity across the test lists, by scrambling lists of sentences of different syntactic types while controlling for linguistic complexity. The original set of test materials was narrowed down to 360 sentences, and list equivalency was evaluated at the audiological and linguistic levels. A psychometric curve was generated with a resolution of 2 dB based on a second group of 60 young normal-hearing native speakers of Dutch and Flemish. RESULTS: Sentence understanding showed an average repetition accuracy of 63.40% (SD 1.01) across the lists at an SNR of -5 dB SPL. No significant differences were found between the lists at the level of the individual listener. At the linguistic level, the sentence lists showed an equal distribution of phonological, morphological, and syntactic features. CONCLUSION: LiCoS combines the clinical benefit of acoustic control at the list level with the high ecological validity of linguistically representative test items. The new speech audiometric test is particularly appropriate to assess sentence understanding in individuals who would otherwise exhibit near-ceiling performance when tested with linguistically more simplified test stimuli. In combination with pure tone audiometric assessment, LiCoS provides valuable complementary information with respect to the functional hearing of patients.

Modernising speech audiometry: using a smartphone application to test word recognition.

OBJECTIVE: This study aimed to develop and assess a method to measure word recognition abilities using a smartphone application (App) connected to an audiometer. DESIGN: Word lists were recorded in South African English and Afrikaans. Analyses were conducted to determine the effect of hardware used for presentation (computer, compact-disc player, or smartphone) on the frequency content of recordings. An Android App was developed to enable presentation of recorded materials via a smartphone connected to the auxiliary input of the audiometer. Experiments were performed to test feasibility and validity of the developed App and recordings. STUDY SAMPLE: Participants were 100 young adults (18-30 years) with pure tone thresholds ≤15 dB across the frequency spectrum (250-8000 Hz). RESULTS: Hardware used for presentation had no significant effect on the frequency content of recordings. Listening experiments indicated good inter-list reliability for recordings in both languages, with no significant differences between scores on different lists at each of the tested intensities. Performance-intensity functions had slopes of 4.05%/dB for English and 4.75%/dB for Afrikaans lists at the 50% point. CONCLUSIONS: The developed smartphone App constitutes a feasible and valid method for measuring word recognition scores, and can support standardisation and accessibility of recorded speech audiometry.

Typical vs. atypical: Combining auditory Gestalt perception and acoustic analysis of early vocalisations in Rett syndrome.

BACKGROUND: Early speech-language development of individuals with Rett syndrome (RTT) has been repeatedly characterised by a co-occurrence of apparently typical and atypical vocalisations. AIMS: To describe specific features of this intermittent character of typical versus atypical early RTT-associated vocalisations by combining auditory Gestalt perception and acoustic vocalisation analysis. METHODS AND PROCEDURES: We extracted N = 363 (pre-)linguistic vocalisations from home video recordings of an infant later diagnosed with RTT. In a listening experiment, all vocalisations were assessed for (a)typicality by five experts on early human development. Listeners' auditory concepts of (a)typicality were investigated in context of a comprehensive set of acoustic time-, spectral- and/or energy-related higher-order features extracted from the vocalisations. OUTCOMES AND RESULTS: More than half of the vocalisations were rated as 'atypical' by at least one listener. Atypicality was mainly related to the auditory attribute 'timbre', and to prosodic, spectral, and voice quality features in the acoustic domain. CONCLUSIONS AND IMPLICATIONS: Knowledge gained in our study shall contribute to the generation of an objective model of early vocalisation atypicality. Such a model might be used for increasing caregivers' and healthcare professionals' sensitivity to identify atypical vocalisation patterns, or even for a probabilistic approach to automatically detect RTT based on early vocalisations.

Evaluation of the NAL Dynamic Conversations Test in older listeners with hearing loss.

OBJECTIVE: The National Acoustic Laboratories Dynamic Conversations Test (NAL-DCT) is a new test of speech comprehension that incorporates a realistic environment and dynamic speech materials that capture certain features of everyday conversations. The goal of this study was to assess the suitability of the test for studying the consequences of hearing loss and amplification in older listeners. DESIGN: Unaided and aided comprehension scores were measured for single-, two- and three-talker passages, along with unaided and aided sentence recall. To characterise the relevant cognitive abilities of the group, measures of short-term working memory, verbal information-processing speed and reading comprehension speed were collected. STUDY SAMPLE: Participants were 41 older listeners with varying degrees of hearing loss. RESULTS: Performance on both the NAL-DCT and the sentence test was strongly driven by hearing loss, but performance on the NAL-DCT was additionally related to a composite cognitive deficit score. Benefits of amplification were measurable but influenced by individual test SNRs. CONCLUSIONS: The NAL-DCT is sensitive to the same factors as a traditional sentence recall test, but in addition is sensitive to the cognitive factors required for speech processing. The test shows promise as a tool for research concerned with real-world listening.

Assessing speech perception in Swedish school-aged children: preliminary data on the Listen-Say test.

To meet the need for a linguistic speech perception test in Swedish, the 'Listen-Say test' was developed. Minimal word pairs were used as speech material to assess seven phonetic contrasts in two auditory backgrounds. In the present study, children's speech discrimination skills in quiet and in four-talker (4T) speech background were examined. Associations with lexical-access skills and academic achievement were explored. The study included 27 school children 7-9 years of age. Overall, the children discriminated phonetic contrasts well in both conditions (quiet: Mdn 95%; 4T speech; Mdn 91% correct). A significant effect of 4T speech background was evident in three of the contrasts, connected to place of articulation, voicing and syllable complexity. Reaction times for correctly identified target words were significantly longer in the quiet condition, possibly reflecting a need for further balancing of the test order. Overall speech discrimination accuracy was moderately to highly correlated with lexical-access ability. Children identified as having high concentration ability by their teacher had the highest speech discrimination scores in both conditions followed by children identified as having high reading ability. The first wave of data collection with the Listen-Say test indicates that the test appears to be sensitive to predicted perceptual difficulties of phonetic contrasts particularly in noise. The clinical benefit of using a procedure where speech discrimination, lexical-access ability and academic achievement are taken into account is discussed as well as issues for further test refinement.

The role of short-time intensity and envelope power for speech intelligibility and psychoacoustic masking.

The generalized power spectrum model [GPSM; Biberger and Ewert (2016). J. Acoust. Soc. Am. 140, 1023-1038], combining the "classical" concept of the power-spectrum model (PSM) and the envelope power spectrum-model (EPSM), was demonstrated to account for several psychoacoustic and speech intelligibility (SI) experiments. The PSM path of the model uses long-time power signal-to-noise ratios (SNRs), while the EPSM path uses short-time envelope power SNRs. A systematic comparison of existing SI models for several spectro-temporal manipulations of speech maskers and gender combinations of target and masker speakers [Schubotz et al. (2016). J. Acoust. Soc. Am. 140, 524-540] showed the importance of short-time power features. Conversely, Jørgensen et al. [(2013). J. Acoust. Soc. Am. 134, 436-446] demonstrated a higher predictive power of short-time envelope power SNRs than power SNRs using reverberation and spectral subtraction. Here the GPSM was extended to utilize short-time power SNRs and was shown to account for all psychoacoustic and SI data of the three mentioned studies. The best processing strategy was to exclusively use either power or envelope-power SNRs, depending on the experimental task. By analyzing both domains, the suggested model might provide a useful tool for clarifying the contribution of amplitude modulation masking and energetic masking.