Acoustic Clarity Research Articles

Impact of clear face masks on audiovisual speech intelligibility and subjective listening effort with normal hearing young adults

During the COVID-19 pandemic, facemask use made people suddenly aware of the importance of both visual information and acoustic clarity in speech perception. Masks with transparent panels can provide listeners with visual speech information, but such masks tend to introduce more acoustic distortion than other opaque masks. Thus, their value for improving speech recognition (at least for listeners with normal hearing) is not clear. In the current study we investigated the ability of three different clear face masks to improve speech intelligibility relative to an opaque surgical mask. Normal hearing young adult participants (N = 180) were presented with audiovisual recordings of 150 sentences from a female speaker in 5 different mask conditions (no mask, surgical mask, and three different clear masks) and at three different signal-to-noise ratios (no noise, –5 dB SNR, and −9 dB SNR). After each condition, participants also completed the NASA-TLX survey for subjective effort. Participants also completed an independent lipreading task. Preliminary data suggest decreased subjective effort and improved performance of the clear masks relative to the opaque mask at high SNR. This implies a potential for visual information to make up for decreased acoustic clarity, making clear masks a better choice in difficult listening conditions.

A modern metric for acoustic clarity in critical listening environments

Characteristics of acoustics in small rooms have become less mysterious, more predictable and measurements more common than in past decades. Modern metrics for characterizing the acoustical performance of critical listening environments have not followed the recent predictive improvements. An Acoustic Clarity metric with a variable time window (Rear Reflection Clarity, CRR) is proposed for small (under approximately 200m3) critical listening environments such as recording studio control, mastering, film post, screening, audiophile listening, and similar rooms. The variable time window is defined by the arrival time difference between direct sound and the reflection from the rear wall, which is typically the strongest reflection and is opposite the on-axis response of the loudspeakers. Measured impulse response data collected in situ is presented and analyzed as case studies to characterize CRR. For simplicity, this presentation will focus on only the stereo components of surround-sound environments.

Differential Auditory and Visual Phase-Locking Are Observed during Audio-Visual Benefit and Silent Lip-Reading for Speech Perception.

Speech perception in noisy environments is enhanced by seeing facial movements of communication partners. However, the neural mechanisms by which audio and visual speech are combined are not fully understood. We explore MEG phase-locking to auditory and visual signals in MEG recordings from 14 human participants (6 females, 8 males) that reported words from single spoken sentences. We manipulated the acoustic clarity and visual speech signals such that critical speech information is present in auditory, visual, or both modalities. MEG coherence analysis revealed that both auditory and visual speech envelopes (auditory amplitude modulations and lip aperture changes) were phase-locked to 2-6 Hz brain responses in auditory and visual cortex, consistent with entrainment to syllable-rate components. Partial coherence analysis was used to separate neural responses to correlated audio-visual signals and showed non-zero phase-locking to auditory envelope in occipital cortex during audio-visual (AV) speech. Furthermore, phase-locking to auditory signals in visual cortex was enhanced for AV speech compared with audio-only speech that was matched for intelligibility. Conversely, auditory regions of the superior temporal gyrus did not show above-chance partial coherence with visual speech signals during AV conditions but did show partial coherence in visual-only conditions. Hence, visual speech enabled stronger phase-locking to auditory signals in visual areas, whereas phase-locking of visual speech in auditory regions only occurred during silent lip-reading. Differences in these cross-modal interactions between auditory and visual speech signals are interpreted in line with cross-modal predictive mechanisms during speech perception.SIGNIFICANCE STATEMENT Verbal communication in noisy environments is challenging, especially for hearing-impaired individuals. Seeing facial movements of communication partners improves speech perception when auditory signals are degraded or absent. The neural mechanisms supporting lip-reading or audio-visual benefit are not fully understood. Using MEG recordings and partial coherence analysis, we show that speech information is used differently in brain regions that respond to auditory and visual speech. While visual areas use visual speech to improve phase-locking to auditory speech signals, auditory areas do not show phase-locking to visual speech unless auditory speech is absent and visual speech is used to substitute for missing auditory signals. These findings highlight brain processes that combine visual and auditory signals to support speech understanding.

الأسلوبیة الصَّوْتیة فی سورة ( المؤمنونَ)

الملخص يعالج هذا البحث نوعا مهما من أنواع ؛ هو: الصوتية، في مادة قرآنية، هي سورة المؤمنون، في ضوء المنهج الوصفي المعني بوصف أصوات کلمات السورة، ومقاطعها، وفواصلها، والصوت الطاغي فيها، والوضوح السمعي في أصوات کلماتها. هذا کله من أجل الکشف عن الإعجاز الصوتي في القرآن الکريم، بصفة عامة، وفي آيات سورة المؤمنون بصفة خاصة. والحق أن أهداف البحث قد اتسقت مع مباحثه الأربعة؛ فقد وردت مؤکدة أهمية الدرس الصوتي، في هذا النص اللغوي القرآني المعجز، وذلک بدراسة أصوات هذه السورة الکريمة سورة المؤمنون ـ مادة الدراسة ـ سواء أکانت أصواتا صامتة (حروفا) أم أصواتا صائتة (حرکات) في إطار الأسلوبية الصوتية، في أبعادها ومعالمها المختلفة، الموزعة على مباحث البحث الأربعة. وقد توصلت ـ بعون من الله وتوفيق ـ إلى مجموعة من النتائج المهمة، المسطرة في نهاية متن هذا البحث. Abstract The study handles a significant type of that is called phonological stylistics in a Quranic material, which is in the light of the descriptive method that is interested in the description of the sounds of the Surah words, sections, intervals, the most dominant sound and audio acoustic clarity of the words' sounds. That is all to reveal the phonological inimitability in the Holy Quran in general and the verses of Surat Al-Mu'minun in particular. Actually, the outcomes of the study are consistent with its four branches of knowledge, because they came to confirm the importance of the phonological lesson in this inimitable linguistic Quranic text, via studying the sounds of this Holy Surah that is called Al-Mu'minun, whether they are consonant sounds (letters) or vowel sounds (diacritics) within the framework of the phonological stylistics of its different dimensions and features, which are distributed to the four branches of knowledge of the present study. The study _by the help of Allah_ reached a group of significant outcomes that are existed in the end of this study.

Fluidity in the perception of auditory speech: Cross-modal recalibration of voice gender and vowel identity by a talking face.

Humans quickly adapt to variations in the speech signal. Adaptation may surface as recalibration, a learning effect driven by error-minimisation between a visual face and an ambiguous auditory speech signal, or as selective adaptation, a contrastive aftereffect driven by the acoustic clarity of the sound. Here, we examined whether these aftereffects occur for vowel identity and voice gender. Participants were exposed to male, female, or androgynous tokens of speakers pronouncing /e/, /ø/, (embedded in words with a consonant-vowel-consonant structure), or an ambiguous vowel halfway between /e/ and /ø/ dubbed onto the video of a male or female speaker pronouncing /e/ or /ø/. For both voice gender and vowel identity, we found assimilative aftereffects after exposure to auditory ambiguous adapter sounds, and contrastive aftereffects after exposure to auditory clear adapter sounds. This demonstrates that similar principles for adaptation in these dimensions are at play.

The Impact of Age, Background Noise, Semantic Ambiguity, and Hearing Loss on Recognition Memory for Spoken Sentences.

The goal of this study was to determine how background noise, linguistic properties of spoken sentences, and listener abilities (hearing sensitivity and verbal working memory) affect cognitive demand during auditory sentence comprehension. We tested 30 young adults and 30 older adults. Participants heard lists of sentences in quiet and in 8-talker babble at signal-to-noise ratios of +15 dB and +5 dB, which increased acoustic challenge but left the speech largely intelligible. Half of the sentences contained semantically ambiguous words to additionally manipulate cognitive challenge. Following each list, participants performed a visual recognition memory task in which they viewed written sentences and indicated whether they remembered hearing the sentence previously. Recognition memory (indexed by d') was poorer for acoustically challenging sentences, poorer for sentences containing ambiguous words, and differentially poorer for noisy high-ambiguity sentences. Similar patterns were observed for Z-transformed response time data. There were no main effects of age, but age interacted with both acoustic clarity and semantic ambiguity such that older adults' recognition memory was poorer for acoustically degraded high-ambiguity sentences than the young adults'. Within the older adult group, exploratory correlation analyses suggested that poorer hearing ability was associated with poorer recognition memory for sentences in noise, and better verbal working memory was associated with better recognition memory for sentences in noise. Our results demonstrate listeners' reliance on domain-general cognitive processes when listening to acoustically challenging speech, even when speech is highly intelligible. Acoustic challenge and semantic ambiguity both reduce the accuracy of listeners' recognition memory for spoken sentences. https://doi.org/10.23641/asha.5848059.

Effects of Age, Acoustic Challenge, and Verbal Working Memory on Recall of Narrative Speech

Background/Study Context: A common goal during speech comprehension is to remember what we have heard. Encoding speech into long-term memory frequently requires processes such as verbal working memory that may also be involved in processing degraded speech. Here the authors tested whether young and older adult listeners’ memory for short stories was worse when the stories were acoustically degraded, or whether the additional contextual support provided by a narrative would protect against these effects.Methods: The authors tested 30 young adults (aged 18–28 years) and 30 older adults (aged 65–79 years) with good self-reported hearing. Participants heard short stories that were presented as normal (unprocessed) speech or acoustically degraded using a noise vocoding algorithm with 24 or 16 channels. The degraded stories were still fully intelligible. Following each story, participants were asked to repeat the story in as much detail as possible. Recall was scored using a modified idea unit scoring approach, which included separately scoring hierarchical levels of narrative detail.Results: Memory for acoustically degraded stories was significantly worse than for normal stories at some levels of narrative detail. Older adults’ memory for the stories was significantly worse overall, but there was no interaction between age and acoustic clarity or level of narrative detail. Verbal working memory (assessed by reading span) significantly correlated with recall accuracy for both young and older adults, whereas hearing ability (better ear pure tone average) did not.Conclusion: The present findings are consistent with a framework in which the additional cognitive demands caused by a degraded acoustic signal use resources that would otherwise be available for memory encoding for both young and older adults. Verbal working memory is a likely candidate for supporting both of these processes.

Vocal comfort and effort in speech: Accommodation to different room acoustic conditions

Background: Vocal effort is a physiological entity that accounts for variation in voice production as loading increases, measured as sound pressure level (SPL). A number of studies have investigated vocal effort and load, but few have considered the role of acoustic clarity (C50), the early to late arriving sound ratio. Method: 20 subjects performed vocal tasks in various room acoustic conditions. Tasks were performed in three styles: soft style, comfortable conversational style, and loud classroom style. C50 in the position of the talker was changed by means of two reflective panels. Two noise levels were used: background noise, and artificial child babble noise. After each task, the subject answered questions addressing their perception of vocal comfort, control and fatigue. SPL and Fundamental Frequency (F0) were measured. Results: When panels were present, talkers perceived the room as being more comfortable to speak in. In particular, in the babble condition and in loud speech, comfort and control tended to increase. Vocal effort (SPL) tended to decrease when panels were present. An assessment of F0 is also reported. The results indicate that even while keeping reverberation time constant, reflective surfaces may be optimized to increase voice comfort and reduce vocal effort.

English

As an important symbol in Islam, a mosque is built with architectural grandeur. Among the characteristics is its high ceiling and it is usually constructed with a typical spherical dome shape. Some mosques, however, are influenced by the local culture and the dome can be of a different shape, such as pyramidal, as found in mosques in Malacca, Malaysia. This paper presents an assessment of the internal acoustical characteristics of a mosque having a pyramidal dome. The study is conducted by means of computer simulation using CATT indoor acoustic software. Reverberation time and clarity are taken to evaluate the intelligibility of speech. The effect of the angle and height of the dome on the acoustical parameters is discussed. It is found that a pyramidal dome with a steeper angle contributes to poor acoustic clarity.

Dynamic mechanical response of plasticizer-laden acoustic polyurethanes extrapolated to higher frequencies using time–temperature superposition technique

Acoustically transparent elastomers are the windows through which the US Navy views the ocean. For acoustic clarity and sensitivity, it is important that these elastomers operate well outside damping conditions as dictated by the temperatures and frequencies of interest. Damping behavior is characterized by a peak in the loss tangent and is associated with transitions in molecular mobility, such as the primary glass–rubber or alpha transition. However, the temperature and frequency location of this peak can shift in response to absorbed plasticizing fluids. This material characteristic is under investigation using dynamic mechanical analysis to assess its dependence on the plasticizer and polyurethane component chemistry. In this second stage of the research, the time–temperature superposition technique was employed to extrapolate storage modulus and loss factor to frequencies beyond the limits of the equipment. The technique appears to be valid for plasticized primary transition behavior but becomes circumspect when applied to secondary transition behavior.

Plasticizer loading in acoustic encapsulants

Acoustically transparent elastomers are the windows through which the United States Navy views the ocean. For acoustic clarity and sensitivity, it is important that the elastomer operates well outside damping conditions as dictated by the temperatures and frequencies of interest. Damping behavior is characterized by a peak in the loss tangent. However, the temperature and frequency location of this peak can shift in response to absorbed plasticizing fluids. This material characteristic is under investigation using dynamic mechanical analysis (DMA) to assess its dependence on the plasticizer and polyurethane component chemistry. In this first stage of the research, a temperature range from −100 to 100 °C and samples saturated with fluid were explored by DMA to determine the limiting behavior of the samples, enabling more detailed investigation in future work. Association of absorbed plasticizers with polyurethane components by polarity was demonstrated in the results by the shifting of the appropriate hard and soft block loss tangent peak.

Cortical responses to degraded speech are modulated by linguistic predictions

Our perceptual experience is formed by combining incoming sensory information with prior knowledge and expectation. When speech is not fully intelligible, non-acoustic information may be particularly important. Predictions about this degraded acoustic signal can be provided intrinsically (if the speech is still partially intelligible) or extrinsically (for example, by presenting a written cue). I will discuss results from studies in which the neural response to speech was measured using magnetoencephalography (MEG), with speech clarity parametrically manipulated using noise vocoding. In one study, we found that during sentence processing the phase of ongoing cortical oscillations is matched to that of the acoustic speech envelope in the range of the syllable rate (4–8 Hz). Critically, this phase-locking was enhanced in left temporal cortex when speech is intelligible. In a separate study of single word listening, accurate predictions provided by written text enhanced subjective clarity and changed the response in early auditory processing regions of temporal cortex. Both experiments thus highlight neural responses in brain regions associated with relatively low-level speech perception. Together these findings support the ability of linguistic information to provide predictions that shape auditory processing of spoken language, particularly when acoustic clarity is compromised.

Effortful Listening: The Processing of Degraded Speech Depends Critically on Attention

The conditions of everyday life are such that people often hear speech that has been degraded (e.g., by background noise or electronic transmission) or when they are distracted by other tasks. However, it remains unclear what role attention plays in processing speech that is difficult to understand. In the current study, we used functional magnetic resonance imaging to assess the degree to which spoken sentences were processed under distraction, and whether this depended on the acoustic quality (intelligibility) of the speech. On every trial, adult human participants attended to one of three simultaneously presented stimuli: a sentence (at one of four acoustic clarity levels), an auditory distracter, or a visual distracter. A postscan recognition test showed that clear speech was processed even when not attended, but that attention greatly enhanced the processing of degraded speech. Furthermore, speech-sensitive cortex could be parcellated according to how speech-evoked responses were modulated by attention. Responses in auditory cortex and areas along the superior temporal sulcus (STS) took the same form regardless of attention, although responses to distorted speech in portions of both posterior and anterior STS were enhanced under directed attention. In contrast, frontal regions, including left inferior frontal gyrus, were only engaged when listeners were attending to speech and these regions exhibited elevated responses to degraded, compared with clear, speech. We suggest this response is a neural marker of effortful listening. Together, our results suggest that attention enhances the processing of degraded speech by engaging higher-order mechanisms that modulate perceptual auditory processing.

Assistive listening devices drive neuroplasticity in children with dyslexia.

Children with dyslexia often exhibit increased variability in sensory and cognitive aspects of hearing relative to typically developing peers. Assistive listening devices (classroom FM systems) may reduce auditory processing variability by enhancing acoustic clarity and attention. We assessed the impact of classroom FM system use for 1 year on auditory neurophysiology and reading skills in children with dyslexia. FM system use reduced the variability of subcortical responses to sound, and this improvement was linked to concomitant increases in reading and phonological awareness. Moreover, response consistency before FM system use predicted gains in phonological awareness. A matched control group of children with dyslexia attending the same schools who did not use the FM system did not show these effects. Assistive listening devices can improve the neural representation of speech and impact reading-related skills by enhancing acoustic clarity and attention, reducing variability in auditory processing.

The just noticeable difference of center time and clarity index in large reverberant spaces

Just noticeable difference (JND) values are available for most acoustical parameters currently used in practice. However, they have been determined with reference to conditions typically encountered in concert halls and in rooms for speech, covering a range of reverberation times (T) spanning from 0.5 s to 2 s. When reverberation gets longer, the relationship between measured parameters describing acoustic clarity may change significantly and subjective perception might also be different. The proposed research investigates the influence of reverberation time on JND for clarity measures taking into account three reference cases having T values varying from 2 s to 6 s. Measured B-format impulse responses were properly modified to introduce the desired changes and then auralized with two music motifs for presentation on a 4-channel playback system. Listening tests based on paired comparisons were carried out to determine subjective limens. The results proved to be independent of music motifs and showed that JND in the clarity index is almost independent of T, while JND in the center time is significantly related to T and can be assumed as the 8.5% of the reference T(S) value.

Speech synthesis system for naturally reading incomplete sentences

To provide a speech synthesis apparatus which can prevent user confusion and deterioration of the quality of synthesized speech resulting from incompleteness of the sentences to be read out, and thus can read out speech which is easily understandable to the user. The speech synthesis apparatus includes: an incomplete part-of-sentence detection unit which detects incomplete parts-of-sentences which become linguistically incomplete because of the presence of a missing character string and which complements the detected incomplete parts-of-sentences having a missing character string, with reference to the e-mail texts which have been received by and accumulated in a mail box; a speech synthesis unit which generates synthesized speech based on the complemented e-mail texts; an incomplete part-of-sentence obscuring unit which obscures the acoustic clarity of the synthesized speech corresponding to the incomplete parts-of-sentences detected by the incomplete part-of-sentence detection unit; and a speaker device which plays back and outputs the generated synthesized speech.