Speech Identification In Noise Research Articles

The effects of temporal cues, point-light displays, and faces on speech identification and listening effort.

Among the most robust findings in speech research is that the presence of a talking face improves the intelligibility of spoken language. Talking faces supplement the auditory signal by providing fine phonetic cues based on the placement of the articulators, as well as temporal cues to when speech is occurring. In this study, we varied the amount of information contained in the visual signal, ranging from temporal information alone to a natural talking face. Participants were presented with spoken sentences in energetic or informational masking in four different visual conditions: audio-only, a modulating circle providing temporal cues to salient features of the speech, a digitally rendered point-light display showing lip movement, and a natural talking face. We assessed both sentence identification accuracy and self-reported listening effort. Audiovisual benefit for intelligibility was observed for the natural face in both informational and energetic masking, but the digitally rendered point-light display only provided benefit in energetic masking. Intelligibility for speech accompanied by the modulating circle did not differ from the audio-only conditions in either masker type. Thus, the temporal cues used here were insufficient to improve speech intelligibility in noise, but some types of digital point-light displays may contain enough phonetic detail to produce modest improvements in speech identification in noise.

Preliminary Findings From the Hearing Assessment in Response to Noise Screener: A New Pediatric Tool for Measuring Speech Identification in Noise

Purpose: As part of the development of a speech-in-noise screener, speech recognition was measured in quiet and in an interrupted noise for 59 children with typical development according to parent report. Method: There were 39 monolingual and 20 bilingual participants. A corpus of 107 words were presented by a male and female speaker and present in the following conditions: +3 dB signal-to- noise ratio (SNR), −3 dB SNR, and quiet. Results: The participants showed increasing difficulty with speech identification as the SNR decreased. Additionally, age-related differences in accuracy were observed at each noise level. Conclusion: Our findings provide preliminary support for the utility and efficacy of a speech-in-noise screener for use with children.

Time-specific Components of Pupil Responses Reveal Alternations in Effort Allocation Caused by Memory Task Demands During Speech Identification in Noise.

Daily communication may be effortful due to poor acoustic quality. In addition, memory demands can induce effort, especially for long or complex sentences. In the current study, we tested the impact of memory task demands and speech-to-noise ratio on the time-specific components of effort allocation during speech identification in noise. Thirty normally hearing adults (15 females, mean age 42.2 years) participated. In an established auditory memory test, listeners had to listen to a list of seven sentences in noise, and repeat the sentence-final word after presentation, and, if instructed, recall the repeated words. We tested the effects of speech-to-noise ratio (SNR; -4 dB, +1 dB) and recall (Recall; Yes, No), on the time-specific components of pupil responses, trial baseline pupil size, and their dynamics (change) along the list. We found three components in the pupil responses (early, middle, and late). While the additional memory task (recall versus no recall) lowered all components' values, SNR (-4 dB versus +1 dB SNR) increased the middle and late component values. Increasing memory demands (Recall) progressively increased trial baseline and steepened decrease of the late component's values. Trial baseline increased most steeply in the condition of +1 dB SNR with recall. The findings suggest that adding a recall to the auditory task alters effort allocation for listening. Listeners are dynamically re-allocating effort from listening to memorizing under changing memory and acoustic demands. The pupil baseline and the time-specific components of pupil responses provide a comprehensive picture of the interplay of SNR and recall on effort.

Acoustical and Perceptual Analysis of Noise Reduction Strategies in Individuals With Auditory Neuropathy Spectrum Disorders.

Purpose The conventional amplification devices render minimal or no benefit at abating the speech perception problems of individuals with auditory neuropathy spectrum disorder (ANSD). This study was undertaken to evaluate the effect of noise reduction strategies (multiband spectral subtraction, Wiener-as, Karhunen-Loeve transform [Subspace], and ideal binary mask [IdBM] algorithm) on speech using speech perception measures and acoustic measure among individuals with ANSD. Method Two groups of participants (age: 17-43 years) were recruited in the study. Group I comprised 12 individuals with a confirmed diagnosis of ANSD and not exceeding moderate degree of hearing loss and Group II of 10 individuals with normal hearing in both ears. The signal-to-noise required for 50% speech recognition (SNR-50) was measured for the participants in five conditions, that is, unprocessed speech and speech processed with four noise reduction strategies. Additionally, an acoustic objective measure Extended Short-Time Objective Intelligibility algorithm was employed to estimate the intelligibility index across the conditions. Results Significant difference was found across conditions in both the groups. Pairwise comparison revealed significantly better speech perception on SNR-50 measure with IdBM strategy, for both the groups. No significant difference in SNR-50 was observed with other noise reduction strategies. IdBM condition also gave the highest intelligibility index (d) values using Extended Short-Time Objective Intelligibility algorithm. This finding needs to be verified on a larger group of individuals with ANSD. Conclusions IdBM noise reduction strategy rendered significantly lower SNR-50 compared to other noise reduction strategies for individuals with ANSD in this study. This provides clinical evidence for the same and also recommends trying on a larger group of participants before its implementation in hearing devices. Apart from this, the current strategies used in hearing aids provide no improvement in speech identification in noise for this population. Hence, though the present hearing aids may show benefit in quiet condition, chances of its rejection are high in noisy backgrounds.

Aging effects on categorical perception of Mandarin tones in noise

The current study aimed at investigating the aging effect on the categorical perception of Mandarin lexical tones with varied fundamental frequency (F0) contours in noise. Mandarin tone identification and tone discrimination in quiet and noise were measured for younger and older listeners in a categorical perception paradigm where the stimuli continua varied their F0 contour systematically from the level to the rising/falling tones. Results reported that older listeners, in contrast with their younger counterparts, performed with less stimulus-tuned changes in both identification and discrimination functions and smaller peakedness in the discrimination function for both level-rising and level-falling tones. The aging effects on Mandarin tone categoricality were observed in both quiet and noise. Moreover, noise aggravated the aging effects, especially with the high SNR condition. Plus, older listeners’ identification and discrimination functions in CP paradigm positively correlated with their performance in general speech identification in noise; such correlation was not found with younger listeners. Our study suggested that older listeners had less categoricality in both identification and discrimination functions for the level-rising and level-falling tones, probably due to the aging-related decline in temporal processing.

BADANIE ZWIĄZKÓW MIĘDZY PAMIĘCIĄ ROBOCZĄ, ROZPOZNAWANIEM MOWY W SZUMIE I P300 U OSÓB DOROSŁYCH Z NIEDOSŁUCHEM

This study investigated the association between working memory capacity (WMC), P300 amplitude and latency, and their relation to speech identification in noise (SiN) in individuals with sensorineural hearing impairment (HI). Twenty adults (mean age=58 years) were recruited and their WMC was measured using a reading span task. SiN was evaluated using the clinical Quick speech-in-noise test. Auditory P300 latency and amplitude, which are known to index information processing, were recorded using a conventional oddball paradigm. WMC was significantly correlated with P300 latency, but was not associated with P300 amplitude (before or after controlling for age and magnitude of HI). In addition, SiN was not significantly correlated with WMC, P300 latency, or amplitude. P300 using tonal stimuli may be a good measure of speed of information processing and attentional control within the working memory system; however, it does not appear to be related to SiN in adults with HI.

Training F0 discrimination improves vowel identification among speech m

Listeners can use voice or fundamental frequency (F0) differences to separate target speech from competing talkers. Discrimination of F0 of harmonic tones has been shown to improve with adaptive training. Here, we examine whether such F0 learning can benefit speech identification in noise. Normal-hearing adults practiced F0 discrimination with standard F0 roved between 120 and 240 Hz. Before and after training, these listeners and a no-contact control group were tested on a vowel identification task, in which Mandarin vowels were embedded within six-talker babble noise at multiple signal-to-noise ratios. After training, the trained listeners improved more than controls on F0 discrimination. Critically, they also improved more in vowel identification. Threshold SNR at 60% intelligibility dropped 1.9 dB as a result of F0 training. The results demonstrate that speech perception in noise can benefit from learning of basic auditory skills, revealing a promising approach for rehabilitative training.

Is There a Relationship Between Speech Identification in Noise and Categorical Perception in Children With Dyslexia?

Children with dyslexia have been suggested to experience deficits in both categorical perception (CP) and speech identification in noise (SIN) perception. However, results regarding both abilities are inconsistent, and the relationship between them is still unclear. Therefore, this study aimed to investigate the relationship between CP and the psychometric function of SIN perception. Sixteen children with dyslexia, 16 chronological-age controls, and 16 reading-level controls were evaluated in CP of a voicing continuum and in consonant identification in both stationary and fluctuating noises. There was a small but significant impairment in speech identification performance of children with dyslexia in stationary noise compared with chronological age-matched controls (but not reading level-matched controls). However, their performance increased in a fluctuating background, hence suggesting normal masking and unmasking effects and preserved sensory processing of speech information. Regarding CP, location of the phoneme boundary differed in the children with dyslexia compared with both control groups. However, scrutinizing individual profiles failed to reveal consistently poor performance in SIN and CP tasks. In addition, there was no significant correlation between CP, SIN perception, and reading scores in the group with dyslexia. The relationship between the SIN deficit and CP, and how they potentially affect reading in children with dyslexia, remains unclear. However, these results are inconsistent with the notion that children with dyslexia suffer from a low-level temporal processing deficit and rather suggest a role of nonsensory (e.g., attentional) factors in their speech perception difficulties.

Hearing Aid-Induced Plasticity in the Auditory System of Older Adults: Evidence From Speech Perception.

We tested whether using hearing aids can improve unaided performance in speech perception tasks in older adults with hearing impairment. Unaided performance was evaluated in dichotic listening and speech-in-noise tests in 47 older adults with hearing impairment; 36 participants in 3 study groups were tested before hearing aid fitting and after 4, 8, and 14 weeks of hearing-aid use. The remaining 11 participants served as a control group and were similarly evaluated but were not fitted with hearing aids. Three protocols were compared in the study groups: amplification for the nondominant ear, amplification for the dominant ear, and bilateral amplification. Subsequently, after 4 weeks, all participants were afforded bilateral amplification. In the study groups, unaided dichotic listening scores improved significantly in the nondominant ear by 8 weeks and onward. Significant improvements were also observed for unaided speech identification in noise, with some gains apparent after 4 weeks of hearing-aid use. No gains were observed in the control group. Using hearing aids for a relatively short period can induce changes in the way older adults process auditory inputs in perceptual tasks such as speech identification in noise and dichotic listening. These changes suggest that the central auditory system of older adults retains the potential for behaviorally relevant plasticity.

How difficult is difficult? Speech perception in noise in the elderly hearing impaired.

Perception of speech in the presence of competing multitalker noise is difficult for most individuals with sensory hearing loss, and in particular, for the elderly hearing impaired. Elderly people frequently report that these difficulties are poorly compensated for by hearing aids, albeit the algorithms and technologies aiming to improve speech perception in noise. The aim of the current study was therefore to assess competing speech signals processing by measuring the amount of signal to noise ratio (SNR) loss experienced by elderly hearing impaired individuals and their performance in dichotic listening tests. Speech in multitalker babble noise and dichotic listening were assessed in older hearing impaired individuals and in young normal-hearing adults. The average dichotic scores in the elderly group were substantially and significantly lower compared with the scores of the younger group with a significant right ear advantage (higher accuracy in reporting words arriving at the right ear than words arriving at the left ear) in the elderly group. Speech identification in noise in the older group was significantly poorer than in the younger group (SNR loss: 10 dB). The poor performance in the elderly hearing impaired group highlights the difficulties faced by hearing impaired older adults in demanding listening environments. Our results suggest that it may be unreasonable to expect that elderly hearing impaired individuals may fully understand speech in multitalker environments even when hearing aids are used.

Personal Amplification for School-Age Children with Auditory Processing Disorders

Children with auditory processing disorders (APD) are described to have a signal-to-noise ratio (SNR) difficulty. Frequency-modulated (FM) systems have been reported to improve this situation. Yet the use of personal amplification that may be more portable has not been attempted. To determine whether personal amplification would result in improvement in speech-in-noise performances (attentiveness and speech recognition) and daily functioning in children with diagnosed APD. In addition, the desired hearing aid features (such as required gain, directional microphone and noise reduction, and open-ear fitting) are examined. A single-blind, longitudinal descriptive study in which subjects served as their own control in various hearing aid conditions. Fourteen normal hearing children who had a diagnosis of APD and who were between the ages of 7 and 11 participated. All subjects wore bilateral, mild-gain, behind-the-ear, wide dynamic range compression hearing aids fitted in an open-ear mode. Gain on the hearing aids was adjusted to provide approximately 10 dB of insertion gain for conversational input. Directional microphone and noise reduction were used on the hearing aids. Subjects wore the hearing aids home and were encouraged to use them as much as possible in their daily environments (school, home, and social activities). Subjects were seen four times: an initial visit where hearing aids were fitted, then visits at 2 weeks, 3 months, and 6 months after the initial fitting. The majority of the testing was completed during these final three visits. The children were evaluated on the Northwestern University word-list (NU-6) and the Auditory Continuous Performance Test (ACPT) in noise at most visits. The hearing aids were evaluated in the omnidirectional microphone mode only, omnidirectional microphone with noise reduction (NR) mode, and directional microphone with NR mode. The children's parents and teachers were asked to complete the Children's Auditory Processing Performance Scale (CHAPS) questionnaire both before and at the end of the study. The results showed that the use of hearing aids in the omnidirectional microphone mode alone did not improve speech identification in noise over the unaided condition. However, the inclusion of the NR algorithm and directional microphones improved speech understanding in noise. Amplification reduced the number of errors on the ACPT and improved several areas on the CHAPS; however, the results were not statistically significant. The use of mild-gain, open-ear fitting hearing aids with a directional microphone and noise reduction algorithm may be attempted on some children with APD on a trial basis.

Spectral shape discrimination and speech identification in noise in elderly hearing-impaired listeners

Elderly hearing-impaired listeners have difficulties in the recognition and discrimination of consonants, particularly those that share the same manner of articulation. An important cue that distinguishes the manner of articulation of these consonants is spectral shape. A previous study (Shrivastav et al., 2006) found a moderate predictive relation between spectral-shape discrimination thresholds and syllable identification scores of elderly hearing-impaired listeners, when all stimuli were presented in quiet. The present study examined the contribution of spectral-shape discrimination abilities to speech-identification performance of elderly hearing-impaired listeners in the presence of background noise. The study included a group of elderly hearing-impaired listeners, with a group of young normal-hearing adults included for comparison purposes. Listeners were tested on a series of speech-identification and spectral-shape discrimination tasks, while ensuring that all stimuli were at least minimally audible to all the hearing-impaired listeners. The contribution of spectral-shape discrimination abilities to speech-identification performance in background noise was examined and compared to the results in quiet for young normal-hearing and older hearing-impaired listeners.

Deficits in speech perception predict language learning impairment

Specific language impairment (SLI) is one of the most common childhood disorders, affecting 7% of children. These children experience difficulties in understanding and producing spoken language despite normal intelligence, normal hearing, and normal opportunities to learn language. The causes of SLI are still hotly debated, ranging from nonlinguistic deficits in auditory perception to high-level deficits in grammar. Here, we show that children with SLI have poorer-than-normal consonant identification when measured in ecologically valid conditions of stationary or fluctuating masking noise. The deficits persisted even in comparison with a younger group of normally developing children who were matched for language skills. This finding points to a fundamental deficit. Information transmission of all phonetic features (voicing, place, and manner) was impaired, although the deficits were strongest for voicing (e.g., difference between/b/and/p/). Children with SLI experienced perfectly normal "release from masking" (better identification in fluctuating than in stationary noise), which indicates a central deficit in feature extraction rather than deficits in low-level, temporal, and spectral auditory capacities. We further showed that speech identification in noise predicted language impairment to a great extent within the group of children with SLI and across all participants. Previous research might have underestimated this important link, possibly because speech perception has typically been investigated in optimal listening conditions using non-speech material. The present study suggests that children with SLI learn language deviantly because they inefficiently extract and manipulate speech features, in particular, voicing. This result offers new directions for the fast diagnosis and remediation of SLI.

Temporal envelope expansion of speech in noise for normal-hearing and hearing-impaired listeners: effects on identification performance and response times

The effects of expanding the temporal envelope of speech sounds on speech identification in noise were investigated in normal-hearing and hearing-impaired listeners. Expansion was performed by applying a power-law transformation to the low-frequency temporal modulations (<500 Hz) of vowel–consonant–vowel logatomes presented against a background noise. Stimuli were spectrally degraded, allowing a direct examination of the perceptual effects induced by the modification of the temporal envelope alone on speech reception. This study extended a previous study conducted by Lorenzi et al. [1999. Hear. Res. 136, 131–138] by measuring the effects of envelope expansion on both identification performance and response times in normal-hearing and hearing-impaired listeners. Overall, the results show that temporal expansion yields only small improvements in identification scores (≈5%) in normal-hearing listeners. No effect of expansion on identification scores was observed in hearing-impaired listeners. On the other hand, the results show that expansion led to a significant decrease in response times in both normal-hearing and hearing-impaired listeners. The average benefit from expansion was about 65 ms in both groups. These results suggest that expanding the temporal envelope of speech sounds presented in noise may improve ‘ease of listening’ in both normal-hearing and hearing-impaired listeners.

Speech identification under simulated hearing-aid frequency response characteristics in relation to sensitivity, frequency resolution, and temporal resolution.

Word identification in noise was measured adaptively under flat and rising frequency response conditions to represent basic alternatives for a hearing-aid characteristic. The speech test results were compared with measures of sensitivity, loudness tolerance, frequency resolution, and temporal resolution in 23 hearing-aid users with mild or moderate sensorineural hearing losses. Subjects also rated the two frequency responses for preference and subjective quality. A paradoxical relationship was found whereby superior speech performance under the flat condition was associated with preference for the rising condition, and vice versa. No combinations of psychoacoustic variables satisfactorily explained either relative performance or preference, although high-frequency sensitivity and upward spread of masking were implicated. Absolute speech performance was related to sensitivity at 2 kHz, age, and sex, but not to frequency resolution once other factors were partialed. Temporal resolution was also a factor, but this was due largely to the influence of extreme values in two subjects. It is concluded that, for moderate degrees of hearing loss, speech identification in noise can be predicted from age, sex, and sensitivity with little advantage from recourse to measurement of frequency or temporal resolution.

Psychoacoustic and phonetic temporal processing in normal and hearing-impaired listeners

Four measures of auditory temporal processing were obtained from 16 normals and 16 individuals with a hearing loss of heterogeneous origin. These measures were: (1) temporal integration—the difference in detection thresholds between signals of 10- and 1000-ms duration (which was determined to provide an estimate of the ability to integrate energy over time), (2) gap detection—the shortest duration of silence between two noise bursts that can be discriminated from an uninterrupted noise, (3) temporal difference limen—the increment in duration necessary to detect a difference in the duration of a noise burst, (4) gap difference limen—the increment in duration necessary to detect a difference in the duration of a silent interval between two noise bursts. Each measure was obtained for stimuli centered both at 500 and at 4000 Hz using a three-alternative forced-choice procedure. In addition, measures of identification and discrimination were obtained for two sets of synthetic speech syllables varying chiefly in a temporal parameter, voice-onset-time, from /ba/ to /pa/ and from /bi/ to /pi/. Finally, speech identification in noise was measured with the FAAF test. Most of the hearing-impaired listeners displayed poorer temporal analysis than the normals on all of the psychoacoustical tasks, regardless of whether the two groups were compared at similar sound pressure levels or at similar sensation levels. Although the hearing-impaired listeners displayed a reduction in the ability to discriminate subphonemic cues for the voiced–voiceless distinction, their identification of that distinction in stop consonants appeared to be normal. The hearing-impaired group made about twice as many errors as did the normals on each of the consonant features of place, manner, and voicing when identifying speech in noise. Increased temporal difference limen and longer gap-detection thresholds were found to correlate significantly with reduced speech intelligibility in noise, even when the effects of the pure-tone threshold loss were partialed out.