Difference In Speech Reception Thresholds Research Articles

Binaural squelch effect in unilateral otosclerosis surgery: comparison of speech intelligibility in noise before-after surgery.

We aimed to evaluate the speech intelligibility benefit in noise provided by stapedotomy in the treatment of unilateral otosclerosis. We enrolled adults suffering from unilateral conductive hearing loss and followed them up until 9months after surgery. The patients underwent a free field speech hearing evaluation using the French Matrix test before and after stapedotomy. Speech material was sent to the front of the patients (S0) and noise was presented either at the front (N0), or at the operated ear (N-90) or at the non-operated ear (N + 90). The speech intelligibility benefit in noise was assessed by comparing Squelch effect (SE), Head shadow effect (HS) and Binaural redundancy (BR) before and after surgery. SE was measured as the difference in speech reception thresholds (SRT) between S0N + 90 situations before and after surgery, HS as the difference in SRT between S0N + 90 and S0N-90 situations, and BR as the difference in SRT between S0N0 situations before and after surgery. In addition, two quality of life's questionnaires were completed by patients to evaluate their discomfort. Among 25 patients, 19 were followed up during 9months, 4 were excluded and 2 were lost for the following-up. Stapedotomy provided a restoration of SE of 3.7dB SNR (p < 0.001) and a BR gain of 1.8dB SNR (p < 0.001). HS did not show any statistical variation after surgery (p = 0.077). Finally, the questionnaires showed a residual hearing discomfort. Stapedotomy provided a binaural benefit with the restoration of the SE and BR but which remained lower than in the normal-hearing population. The 07/02/2018 on Clinical.Trial.Gouv: NCT03587792.

Speech Understanding With Various Maskers in Cochlear-Implant and Simulated Cochlear-Implant Hearing: Effects of Spectral Resolution and Implications for Masking Release.

The purpose of this study was to investigate the relationship between psychophysical spectral resolution and sentence reception in various types of interfering backgrounds for listeners with cochlear implants and normal-hearing subjects listening to vocoded speech. Spectral resolution was measured with a spectral modulation detection (SMD) task. For speech testing, maskers included stationary speech-shaped noise (SSN), four-talker babble, multitone noise, and a competing talker. To explore the possible trade-offs between spectral resolution and susceptibility to different types of maskers, the degree of simulated current spread was varied within the vocoder group, achieving a range of performance for SMD and speech tasks. Greater simulated current spread was detrimental to both spectral resolution and speech recognition, suggesting that interventions that decrease current spread may improve performance for both tasks. Better SMD sensitivity was significantly correlated with improved sentence reception. In addition, differences in sentence reception across the four maskers were significantly associated with SMD across the combined group of cochlear-implant and vocoder subjects. Masking release (MR) was quantified as the signal-to-noise ratio difference in speech reception threshold between the SSN and competing talker. Several individual cochlear-implant subjects demonstrated substantial MR, in contrast to previous studies, and the degree of MR increased with better SMD thresholds across subjects. The results of this study suggest that alternative masker types, particularly competing talkers, are more sensitive than stationary SSN to differences in spectral resolution in the cochlear-implant population.

Factors Influencing Cochlear Patency after Translabyrinthine Surgery.

Objective To determine predictive factors for cochlear obliteration after translabyrinthine surgery for vestibular schwannoma. Study Design Case series with chart review. Setting Neurotology referral center. Subjects and Methods In total, 345 charts were reviewed, resulting in 103 patients who underwent translabyrinthine surgery between January 2010 and July 2015 and had postoperative magnetic resonance imaging (MRI) for review. Surveillance MRI performed after translabyrinthine resection of vestibular schwannomas was reviewed. Heavily T2-weighted MRI obtained an average of 21.8 months after surgery was reviewed to assess cochlear patency. Tumor size, preoperative audiograms, and MRI cochlear fluid-attenuated inversion recovery (FLAIR) intensity were compared between patients with retained cochlear patency and those without. Results Fifty-four percent of patients retained cochlear patency after translabyrinthine surgery. Tumor size did not differ statistically between the 2 groups. There was no statistically significant difference in speech reception thresholds, pure-tone average, or word recognition scores between patent and nonpatent groups. Preoperative MRI FLAIR intensity did not differ between groups. Conclusions More than half of patients retain cochlear patency after translabyrinthine vestibular schwannoma surgery. Cochlear patency is required for cochlear implant in patients with unilateral deafness. Preoperative tumor size, hearing performance, and intensity on MRI FLAIR do not predict cochlear patency. To prevent loss of opportunity for cochlear implantation, simultaneous implantation and cochlear lumen keeper placement are options.

Relationship between multipulse integration and speech recognition with cochlear implants.

Comparisons of performance with cochlear implants and postmortem conditions in the cochlea in humans have shown mixed results. The limitations in those studies favor the use of within-subject designs and non-invasive measures to estimate cochlear conditions. One non-invasive correlate of cochlear health is multipulse integration, established in an animal model. The present study used this measure to relate neural health in human cochlear implant users to their speech recognition performance. The multipulse-integration slopes were derived based on psychophysical detection thresholds measured for two pulse rates (80 and 640 pulses per second). A within-subject design was used in eight subjects with bilateral implants where the direction and magnitude of ear differences in the multipulse-integration slopes were compared with those of the speech-recognition results. The speech measures included speech reception threshold for sentences and phoneme recognition in noise. The magnitude of ear difference in the integration slopes was significantly correlated with the magnitude of ear difference in speech reception thresholds, consonant recognition in noise, and transmission of place of articulation of consonants. These results suggest that multipulse integration predicts speech recognition in noise and perception of features that use dynamic spectral cues.

Factors Influencing Individual Variation in Perceptual Directional Microphone Benefit

Large variations in perceptual directional microphone benefit, which far exceed the variation expected from physical performance measures of directional microphones, have been reported in the literature. The cause for the individual variation has not been systematically investigated. To determine the factors that are responsible for the individual variation in reported perceptual directional benefit. A correlational study. Physical performance measures of the directional microphones obtained after they had been fitted to individuals, cognitive abilities of individuals, and measurement errors were related to perceptual directional benefit scores. Fifty-nine hearing-impaired adults with varied degrees of hearing loss participated in the study. All participants were bilaterally fitted with a Motion behind-the-ear device (500 M, 501 SX, or 501 P) from Siemens according to the National Acoustic Laboratories' non-linear prescription, version two (NAL-NL2). Using the Bamford-Kowal-Bench (BKB) sentences, the perceptual directional benefit was obtained as the difference in speech reception threshold measured in babble noise (SRTn) with the devices in directional (fixed hypercardioid) and in omnidirectional mode. The SRTn measurements were repeated three times with each microphone mode. Physical performance measures of the directional microphone included the angle of the microphone ports to loudspeaker axis, the frequency range dominated by amplified sound, the in situ signal-to-noise ratio (SNR), and the in situ three-dimensional, articulation-index weighted directivity index (3D AI-DI). The cognitive tests included auditory selective attention, speed of processing, and working memory. Intraparticipant variation on the repeated SRTn's and the interparticipant variation on the average SRTn were used to determine the effect of measurement error. A multiple regression analysis was used to determine the effect of other factors. Measurement errors explained 52% of the variation in perceptual directional microphone benefit (95% confidence interval [CI]: 34-78%), while another 37% of variation was explained primarily by the physical performance of the directional microphones after they were fitted to individuals. The most contributing factor was the in situ 3D AI-DI measured across the low frequencies. Repeated SRTn measurements are needed to obtain a reliable indication of the perceptual directional benefit in an individual. Further, to obtain optimum benefit from directional microphones, the effectiveness of the microphones should be maximized across the low frequencies.

Effects of reverberation and masker fluctuations on binaural unmasking of speech

In daily life, listeners use two ears to understand speech in situations which typically include reverberation and non-stationary noise. In headphone experiments, the binaural benefit for speech in noise is often expressed as the difference in speech reception threshold between diotic (N(0)S(0)) and dichotic (N(0)S(π)) conditions. This binaural advantage (BA), arising from the use of inter-aural phase differences, is about 5-6 dB in stationary noise, but may be lower in everyday conditions. In the current study, BA was measured in various combinations of noise and artificially created diotic reverberation, for normal-hearing and hearing-impaired listeners. Speech-intelligibility models were applied to quantify the combined effects. Results showed that in stationary noise, diotic reverberation did not affect BA. BA was reduced in conditions where the masker fluctuated. With additional reverberation, however, it was restored. Results for both normal-hearing and hearing-impaired listeners were accounted for by assuming that binaural unmasking is only effectively realized at low instantaneous speech-to-noise ratios (SNRs). The observed BA was related to the distribution of SNRs resulting from fluctuations, reverberation, and peripheral processing. It appears that masker fluctuations and reverberation, both relevant for everyday communication, interact in their effects on binaural unmasking and need to be considered together.

The Developmental Trajectory of Spatial Listening Skills in Normal-Hearing Children

To establish the age at which children can complete tests of spatial listening and to measure the normative relationship between age and performance. Fifty-six normal-hearing children, ages 1.5-7.9 years, attempted tests of the ability to discriminate a sound source on the left from one on the right, to localize a source, to track moving sources, and to perceive speech in noise. Tests of left-right discrimination, movement tracking, and speech perception were completed by ≥ 75% of children older than 3 years. Children showed adult levels of performance from age 1.5 years (movement tracking), 3 years (left-right discrimination), and 6 years (localization and speech in noise). Spatial release from masking-calculated as the difference in speech reception thresholds between conditions with spatially coincident and spatially separate sp-eech and noise--remained constant at 5 dB from age 3 years. Data from a separate study demonstrate the age at which children with cochlear implants can complete the same tests. Assessments of left-right discrimination, movement tracking, and speech perception were completed by ≥ 75% of children who are older than 5 years and who wear cochlear implants. These data can guide the selection of tests for future studies and inform the interpretation of results from clinical populations.

Comparison of the Audiologic Results Obtained With the Bone-Anchored Hearing Aid Attached to the Headband, the Testband, and to the "Snap" Abutment

1) To quantify the audiometric differences between the preoperative tests with the Bone-Anchored Hearing Aid (BAHA) attached to the headband or the testband and the final postoperative result with the BAHA positioned at the implanted abutment. 2) To compare the results obtained with the headband and the testband. 3) To quantify the magnitude of the damping through the skin for the BAHA placed at the testband (important for comparison with the implantable hearing aids). Prospective. Tertiary otological referral centre. Ten adult (> or = 14 yr old) BAHA patients (6 male and 4 female subjects) with bilateral air-bone gaps of minimum 40-dB hearing loss and with more than 6 months of BAHA experience with the BAHA "Compact." Audiometric free-field thresholds and speech audiometry scores (Consonant-Vowel-Consonant lists, phonemic score) have been evaluated for 3 conditions: BAHA attached to the implanted "Snap" abutment, to the headband, or to the testband. For frequencies 1 to 4 kHz, significant differences in the range of 5 to 20 dB were found between the BAHA coupled with the Snap abutment and the preoperative testing conditions with the BAHA positioned at the headband or the testband. These differences were also reflected in the speech audiometry with a difference in speech reception threshold of approximately 4 to 7 dB. 1) Significant differences in the audiometric thresholds and the speech understanding scores were found between the preoperative test conditions and the final postoperative result. 2) Audiometric results obtained with the headband and the testband are comparable; therefore, the more comfortable headband is also suitable for the preoperative audiologic evaluation. 3) The magnitude of the skin damping must be accounted for when referring to the audiometric results obtained with the BAHA attached to the testband or headband.

Clear speech perception in acoustic and electric hearing

When instructed to speak clearly for people with hearing loss, a talker can effectively enhance the intelligibility of his/her speech by producing "clear" speech. We analyzed global acoustic properties of clear and conversational speech from two talkers and measured their speech intelligibility over a wide range of signal-to-noise ratios in acoustic and electric hearing. Consistent with previous studies, we found that clear speech had a slower overall rate, higher temporal amplitude modulations, and also produced higher intelligibility than conversational speech. To delineate the role of temporal amplitude modulations in clear speech, we extracted the temporal envelope from a number of frequency bands and replaced speech fine-structure with noise fine-structure to simulate cochlear implants. Although both simulated and actual cochlear-implant listeners required higher signal-to-noise ratios to achieve normal performance, a 3-4 dB difference in speech reception threshold was preserved between clear and conversational speech for all experimental conditions. These results suggest that while temporal fine structure is important for speech recognition in noise in general, the temporal envelope carries acoustic cues that contribute to the clear speech intelligibility advantage.

Temporal envelope and fine structure cues for speech intelligibility

A number of listening experiments were run to investigate the relative contribution of temporal envelope modulations and fine structure to speech intelligibility. Firstly, the amplitude envelopes of 24 1/4-oct bands (100–6400 Hz) were processed in several ways (e.g., fast compression) to assess the importance of modulation peaks and troughs. Results show that reduction of modulations by the addition of noise is more detrimental to sentence intelligibility than the same degree of reduction achieved by direct manipulation of the envelope; in some cases the difference in speech-reception threshold (SRT) is almost 10 dB. Here, Leq−3 dB defines a perceptual cross-over level for which removing modulations either x dB below or above yields the same intelligibility score, whereas Leq−15 dB defines the median envelope level (acoustic cross-over level). Secondly, the fine structure of each 1/4-oct band was altered by manipulating the distribution of speech and noise over the sentences. Results indicate that noiseless peaks do not increase intelligibility; removing the speech fine structure in the troughs, however, yields a 2-dB increase of the SRT. In general, no one-to-one relation between the modulation-transfer function (MTF) and the intelligibility scores could be established. [Work supported by NWO.]

Contributions of comodulation masking release and temporal resolution to the speech-reception threshold masked by an interfering voice

Two experiments are presented to explain the difference in speech-reception threshold (SRT) between conditions with a steady-state noise masker or an interfering voice. Literature shows for normal hearing a masking release of 6-8 dB with an interfering voice and a substantial reduction of this release with hearing impairment. In experiment I the possible role of comodulation masking release (CMR) is investigated by manipulating the comodulation in the interfering voice by the introduction of temporal shift among filter bands of various width. The spectral spread of masking from the manipulated interfering voice was controlled by interleaving the mutually shifted speech bands with 1/3-octave bands of noise. Although comodulation in the interfering speech appears to be very important for the low SRT, the contribution of across-frequency processing of masker fluctuations--commonly considered as the origin of CMR--is only 1.3 dB. In experiment II the level dependence of masking release with an interfering voice is investigated. The data fit in with the hypothesis by Festen and Plomp [J. Acoust. Soc. Am. 88, 1725-1736 (1990)] that the release from masking with an interfering voice is limited by forward masking. It appears that up to about 55 dBA the release from masking increases with level up to about 7 dB. Above 55 dBA the difference in SRT obtained with a noise masker or an interfering voice is constant due to the limited average modulation depth of speech.

Why do masker fluctuations as in interfering speech lower the speech-reception threshold?

Two experiments will be presented to explain the difference in speech-reception threshold (SRT) between conditions with a steady-state noise masker and an interfering voice. In experiment I, the possible role of comodulation masking release is investigated by manipulating the comodulation in the interfering voice by introduction of temporal shift among filter bands of various width. The spectral spread of masking from the manipulated interfering voice was controlled by interleaving mutually shifted speech bands with 1/3-octave bands of noise. Although comodulation in interfering speech appears to be very important for the low SRT, the contribution of across-frequencyprocessing of masker fluctuations—commonly considered as the origin of CMR—is only 1.3 dB. In experiment II, the level dependence of masking release with an interfering voice is investigated. The data confirm the hypothesis by Festen and Plomp (1990) that the release from masking with an interfering voice is limited by forward masking. It appears that up to about 55 dBA, the release from masking increases with level up to about 7 dB. Above 55 dBA, the difference in SRT obtained with a noise masker or an interfering voice is constant due to the limited modulation depth of speech.

The use of single-channel compression for the improvement of speech intelligibility.

In this study, speech perception with commercially available linear and single-channel input- and output-dependent compression aids was investigated. Although compression has been introduced as a method of limiting the maximum output, theoretically expectations have been raised that a gain in speech intelligibility could also be obtained by a better use of the reduced dynamic range of the patient. It turned out that there was no significant difference in speech reception thresholds obtained both in quiet and in noise between the aids used for a group of 12 hearing-impaired hearing-aid users as a whole, or for different subgroups thereof.