A Comparison Between the Korean Digits-in-Noise Test and the Korean Speech Perception-in-Noise Test in Normal-Hearing and Hearing-Impaired Listeners

Background and Objectives: The purpose of the present study was to validate the performance and diagnostic efficacy of the Korean digits-in-noise (K-DIN) test in comparison to the Korean speech perception-in-noise (K-SPIN) test, which is the representative speech-in-noise test in clinical practice.Subjects and Methods: Twenty-seven subjects (15 normal-hearing and 12 hearing-impaired listeners) participated. The recorded Korean 0-9 digits were used to form quasirandom digit triplets; 50 target digit triplets were presented at the most comfortable level of each subject while presenting speech-shaped background noise at various levels of signal-to-noise ratios (-12.5, -10, -5, or +5 dB). Subjects were then instructed to listen to both target and noise masker unilaterally and bilaterally through a headphone. K-SPIN test was also conducted using the same procedure as the K-DIN. After calculating their percent correct responses, K-DIN and K-SPIN results were compared using a Pearson-correlation test.Results: Results showed a statistically significant correlation between K-DIN and K-SPIN in all hearing conditions (left: r=0.814, p<0.001; right: r=0.788, p<0.001; bilateral: r=0.727, p<0.001). Moreover, the K-DIN test achieved better testing efficacy, shorter average listening time (5 min vs. 30 min), and easier performance of task according to participants’ qualitative reports than the K-SPIN test.Conclusions: In this study, the Korean version of digit triplet test was validated in both normal-hearing and hearing-impaired listeners. The findings suggest that the K-DIN test can be used as a simple and time-efficient hearing-in-noise test in audiology clinics in Korea.

An electrophysiological measure of tonotopic selectivity in normal-hearing humans and cats

We describe a non-invasive electrophysiological (EEG) measure of tonotopic selectivity and compare the results between humans and cats. Sequences of 50-ms tone-burst probes were presented at 1-second intervals against a continuous noise masker, and the averaged cortical onset response (COR) to the probe was measured using EEG electrodes placed on the scalp. The noise masker had a bandwidth of 1 or 1/8th octave, geometrically centred on 4000 Hz for humans and 8000 Hz for cats. Probe frequency was either -0.5, -0.25, 0, 0.25 or 0.5 octaves re 4000/8000 Hz. The COR was larger for probe frequencies more distant from the noise geometrical centre, and this effect was greater for the 1/8th-octave than for the 1-octave masker. This pattern broadly reflected the masked excitation patterns obtained psychophysically with similar stimuli in a companion paper. However, the positive signal-to-noise ratio used to obtain reliable COR measures meant that some aspects of the data differed from those obtained psychophysically, in a way that could be partly explained by the upward spread of the probe’s excitation pattern. We argue that although COR measures are affected by some factors that differ from those that influence psychophysical masked detection thresholds, they can reveal differences in the width of excitation patterns produced by different stimuli. We also argue that the paradigm may be effectively applied to cochlear-implant experiments in humans and animals.

Does Sentence-Level Coarticulation Affect Speech Recognition in Noise or a Speech Masker?

Purpose Three experiments were conducted to better understand the role of between-word coarticulation in masked speech recognition. Specifically, we explored whether naturally coarticulated sentences supported better masked speech recognition as compared to sentences derived from individually spoken concatenated words. We hypothesized that sentence recognition thresholds (SRTs) would be similar for coarticulated and concatenated sentences in a noise masker but would be better for coarticulated sentences in a speech masker. Method Sixty young adults participated ( n = 20 per experiment). An adaptive tracking procedure was used to estimate SRTs in the presence of noise or two-talker speech maskers. Targets in Experiments 1 and 2 were matrix-style sentences, while targets in Experiment 3 were semantically meaningful sentences. All experiments included coarticulated and concatenated targets; Experiments 2 and 3 included a third target type, concatenated keyword-intensity–matched (KIM) sentences, in which the words were concatenated but individually scaled to replicate the intensity contours of the coarticulated sentences. Results Regression analyses evaluated the main effects of target type, masker type, and their interaction. Across all three experiments, effects of target type were small (< 2 dB). In Experiment 1, SRTs were slightly poorer for coarticulated than concatenated sentences. In Experiment 2, coarticulation facilitated speech recognition compared to the concatenated KIM condition. When listeners had access to semantic context (Experiment 3), a coarticulation benefit was observed in noise but not in the speech masker. Conclusions Overall, differences between SRTs for sentences with and without between-word coarticulation were small. Beneficial effects of coarticulation were only observed relative to the concatenated KIM targets; for unscaled concatenated targets, it appeared that consistent audibility across the sentence offsets any benefit of coarticulation. Contrary to our hypothesis, effects of coarticulation generally were not more pronounced in speech maskers than in noise maskers.

AMBIENT NOISE: PROBLEM AND STUDY IN THE FRAMEWORK OF UAV AEROACOUSTICS

The role of ambient noise in the problem of community noise of propeller-driven unmanned aerial vehicle is considered. The results of the author's measurements of the spectral characteristics of the background in open terrain, in the mountains, near the sea and the highway are presented. An expression is proposed for calculating the spectrum of background noise in open terrain (wind noise). It is shown that the ambient noise can be an effective noise masker of propeller-driven UAV in the low and medium frequencies.

The Clear-Speech Benefit for School-Age Children: Speech-in-Noise and Speech-in-Speech Recognition

Purpose Talkers often modify their speech when communicating with individuals who struggle to understand speech, such as listeners with hearing loss. This study evaluated the benefit of clear speech in school-age children and adults with normal hearing for speech-in-noise and speech-in-speech recognition. Method Masked sentence recognition thresholds were estimated for school-age children and adults using an adaptive procedure. In Experiment 1, the target and masker were summed and presented over a loudspeaker located directly in front of the listener. The masker was either speech-shaped noise or two-talker speech, and target sentences were produced using a clear or conversational speaking style. In Experiment 2, stimuli were presented over headphones. The two-talker speech masker was diotic (M 0 ). Clear and conversational target sentences were presented either in-phase (T 0 ) or out-of-phase (T π ) between the two ears. The M 0 T π condition introduces a segregation cue that was expected to improve performance. Results For speech presented over a single loudspeaker (Experiment 1), the clear-speech benefit was independent of age for the noise masker, but it increased with age for the two-talker masker. Similar age effects for the two-talker speech masker were seen under headphones with diotic presentation (M 0 T 0 ), but comparable clear-speech benefit as a function of age was observed with a binaural cue to facilitate segregation (M 0 T π ). Conclusions Consistent with prior research, children showed a robust clear-speech benefit for speech-in-noise recognition. Immaturity in the ability to segregate target from masker speech may limit young children's ability to benefit from clear-speech modifications for speech-in-speech recognition under some conditions. When provided with a cue that facilitates segregation, children as young as 4–7 years of age derived a clear-speech benefit in a two-talker masker that was similar to the benefit experienced by adults.

Pupil dilation is sensitive to semantic ambiguity and acoustic degradation

Speech comprehension is often challenged by background noise or other acoustic interference. It can also be challenged by linguistic factors, such as complex syntax, or the presence of words with more than one meaning. Pupillometry is increasingly recognized as a technique that provides a window onto acoustic challenges, but this work has not been well integrated with an older literature linking pupil dilation to “mental effort”, which would include linguistic challenges. Here, we measured pupil dilation while listeners heard spoken sentences with clear sentence-level meaning that contained words with more than one meaning (“The shell was fired towards the tank”) or matched sentences without ambiguous words (“Her secrets were written in her diary”). This semantic-ambiguity manipulation was crossed with an acoustic manipulation: two levels of a 30-talker babble masker in Experiment 1; and presence or absence of a pink noise masker in Experiment 2. Speech comprehension, indexed by a semantic relatedness task, was high (above 82% correct) in all conditions. Pupils dilated when sentences included semantically ambiguous words compared to matched sentences and when maskers were present compared to absent (Experiment 2) or were more compared to less intense (Experiment 1). The current results reinforce the idea that many different challenges to speech comprehension, that afford different cognitive processes and are met by the brain in different ways, manifest as an increase in pupil dilation.

Effects of Low- and High-Frequency Side Bands of Notched Noise on Masking and Auditory Filter Shape at Very High Frequencies

This paper is concerned with the determination of the auditory filter shape using the notched noise method with noise bands symmetrically located above and below a probe frequency of 10 kHz. Unlike in the classical experiments conducted with the use of Patterson method the levels as well as power spectrum densities of the lower and upper component bands of the notched noise masker were not the same and were set such as to produce the same amount of masking at the 10-kHz frequency. The experiment consisted of three conditions in which the following values were determined: (I) the detection threshold for a 10-kHz probe tone in the presence of a noise masker presented below the tone’s frequency; (II) the level of a noise masker presented above the 10-kHz probe tone frequency, at which the masker just masked the probe tone, (III) the detection threshold for a probe tone in the presence of a notched-noise masker. The data show a considerable amount of variability across the subjects, however, the resulting frequency characteristics of the auditory filters are consistent with those presented in the literature so that the Equivalent Rectangular Bandwidth is less than 11% of their centre frequency.