Speech Reception Thresholds In Quiet Research Articles

Speech intelligibility and its relation to auditory temporal processing in Czech and Swiss German subjects with and without tinnitus.

Previous studies have shown that levels for 50% speech intelligibility in quiet and in noise differ for different languages. Here, we aimed to find out whether these differences may relate to different auditory processing of temporal sound features in different languages, and to determine the influence of tinnitus on speech comprehension in different languages. We measured speech intelligibility under various conditions (words in quiet, sentences in babble noise, interrupted sentences) along with tone detection thresholds in quiet [PTA] and in noise [PTAnoise], gap detection thresholds [GDT], and detection thresholds for frequency modulation [FMT], and compared them between Czech and Swiss subjects matched in mean age and PTA. The Swiss subjects exhibited higher speech reception thresholds in quiet, higher threshold speech-to-noise ratio, and shallower slope of performance-intensity function for the words in quiet. Importantly, the intelligibility of temporally gated speech was similar in the Czech and Swiss subjects. The PTAnoise, GDT, and FMT were similar in the two groups. The Czech subjects exhibited correlations of the speech tests with GDT and FMT, which was not the case in the Swiss group. Qualitatively, the results of comparisons between the Swiss and Czech populations were not influenced by presence of subjective tinnitus. The results support the notion of language-specific differences in speech comprehension which persists also in tinnitus subjects, and indicates different associations with the elementary measures of auditory temporal processing.

Diagnosing and Screening in a Minority Language: A Validation Study.

The Turkish Digit Triplet Test for hearing self-screening purposes and the Turkish Matrix Test (TURMatrix) for follow-up hearing diagnostics offer an automated closed-set response format where patients respond by choosing from response alternatives. Their applicability for testing Turkish-speaking patients in their native language by German audiologists with different Turkish language skills was investigated. Tests were composed of spoken numbers (Turkish Digit Triplet Test) or sentences (TURMatrix). For 49 participants differing in hearing ability, speech reception thresholds (SRTs) in noise and quiet were obtained, for the TURMatrix with either the open- or closed-set response format, by audiologists with and without Turkish language skills, respectively. SRTs of both tests correlate closely with each other as well as with hearing ability, but not as closely as individual SRTs in quiet with hearing ability. SRTs in noise of listeners with normal hearing were about 0.7 dB lower for the closed-set than for the open-set response format. The 2 tests yield comparable results and are applicable to professionals without suitable language skills. For the closed-set response format of the TURMatrix, literacy is crucial and supplemental (visual) cues improve performance. Speech audiometry in noise should assess suprathreshold processing deficits independently from language proficiency in the majority language.

Amplitude-modulation detection and speech recognition in normal and hearing-impaired listeners

Even though temporal speech envelopes may form a salient cue when listening to speech in noisy backgrounds, the relationship between speech intelligibility and the sensitivity to detecting temporal envelopes (i.e., amplitude modulation detection) is not well understood. This study measured speech reception thresholds in quiet, stationary and speech-modulated noise in three listener groups: young (yNH) and older normal-hearing (oNH) listeners and hearing-impaired (HI) listeners. In addition to broadband speech and noise signals, we adopted low and high-pass filtered versions of the stimuli to study the contribution of different coding mechanisms in basal and apical cochlear regions. For the same listeners, amplitude-modulation (AM) detection thresholds were measured in quiet and in the presence of broadband masking noise for 70 dB AM tones of 0.5, 2 and 4 kHz with either 100 or 5 Hz modulation frequency. Even though group trends were clearer than individual differences, AM detection thresholds showed a relationship to speech recognition in the low-pass filtered speech-modulated noise condition, and for yNH and oNH listeners in the high-pass filtered condition. Overall, this study sheds light on the importance of temporal envelope coding sensitivity for speech recognition and its relationship to near-and supra-threshold hearing deficits.

Emergence of Binaural Summation After Surgical Correction of Unilateral Congenital Aural Atresia.

To investigate the emergence of binaural summation in patients with unilateral congenital aural atresia undergoing surgical correction. Preoperative and postoperative audiometric testing in a prospective cohort of 10 patients with unilateral congenital aural atresia. University-based tertiary care center. Ten patients (ages 6-53) with an average 69 dB (±9 dB sd) unilateral conductive hearing loss, normal hearing in the nonatretic ear, and normal bone conduction in the atretic ear. Pre- and postoperative hearing in noise test in quiet and in noise. Levels of sentences presented from a single central speaker were adaptively varied to determine a speech reception threshold (SRT), first in quiet and then with simultaneous multitalker babble at 65 dB SPL from the same speaker. Preoperative SRT was worse than normal controls in both quiet (p = 0.001) and in noise (p = 0.05), as expected. Postoperative SRT in quiet improved 3.5 dB (marginally significant with one-tailed p value of 0.05); thresholds in noise improved an insignificant 0.8 dB (one-tailed p = 0.2). Converting results to dB-worse-than normal, atresia patients did better in noise (relative to normal) than in quiet (p = 0.008). The expected summation effect (3 dB) occurs after atresia surgery in quiet but not in noise. Relative to normal, these patients performed better in noise than quiet, perhaps because these patients develop skills attending to threshold-level speech in noise during their years without binaural benefit.

Development and evaluation of the Turkish matrix sentence test

Objectives: The Turkish matrix sentence test, TURMatrix, was developed for precise, internationally comparable speech intelligibility testing. Design: The TURMatrix comprises a base matrix of ten well-known Turkish names, numbers, adjectives, objects, verbs, from which syntactically fixed sentences were randomly composed. Test conduction may be in an open-set (standard), or closed-set response format. Homogeneity in intelligibility of the test material was optimized by applying level adaptations (maximal ± 3 dB) based on word-specific speech reception thresholds (SRTs). Test list equivalence was verified and reference values were determined. Study sample: Thirty-eight native listeners of Turkish with normal hearing. Results: After training, mean SRT and slope of the final test lists were − 8.3 ± 0.2 dB SNR and 14.1 ± 1.0%/dB, respectively (fixed SNR measurements; inter-list variability). For adaptive measurements, average across listeners was − 7.2 ± 0.7 dB SNR in the open-set and − 7.9 ± 0.7 dB SNR in the closed-set response format. Mean SRT for adaptive measurements in the open-set response format in quiet was 20.3 ± 4.1 dB. Individual SRTs in quiet correlated more closely with audiograms than with SRTs in noise. Conclusions: The TURMatrix was developed according to European standards and provides reliable speech intelligibility measurements in noise and quiet.

Changes in children's speech discrimination and spatial release from masking between 2 and 4 years after sequential cochlear implantation

Objective: To document changes in speech reception thresholds (SRTs) and spatial release from masking (SRM) for sequentially implanted children at 2 and 4 years after they received their second cochlear implant (CI2).Methods: Participants were 17 children who consistently used two sequentially implanted and optimally programmed CIs. SRTs were measured monaurally in quiet and binaurally in noise using the adaptive McCormick toy discrimination test. Speech signals were presented from 0° azimuth and noise from 0°, +90° or −90° azimuth. SRM was calculated from SRTs in noise. Measurements were made at 2 and 4 year post-CI2.Results: There were significant improvements over time in SRTs in quiet, SRTs in noise and SRM. SRTs in quiet improved more for CI2 than for the first implant (CI1). SRTs in noise and SRM improved more when noise was presented closest to CI1 than when closest to CI2. Performance became more symmetrical over time.Discussion: Despite prolonged periods of unilateral auditory deprivation sequentially implanted children exhibited continued improvement in SRT and SRM. These results are valuable in setting expectations for and counselling families of children considering sequential CIs.

Transcutaneous bone-conduction hearing device: audiological and surgical aspects in a first series of patients with mixed hearing loss

Conclusions: The Bonebridge® (BB) transcutaneous bone conductive implant (BCI) may overcome some of the issues related to a percutaneous BCI, such as management of the external screw, delayed activation or possible skin complications. Moreover, it has been shown to enable a functional outcome similar to percutaneous BCI in both conductive and mixed types of hearing loss. Objectives: To obtain clinical data from a preliminary series of patients implanted with a new transcutaneous BCI. Methods: Four subjects affected by conductive/mixed hearing loss underwent implantation of the BB by two approaches: the transmastoid, presigmoid approach and the retrosigmoid approach. Soundfield thresholds were assessed with warble tones in a soundproof audiometric booth, and word recognition scores (WRSs) as speech reception thresholds (SRTs) were used to compare the unaided versus the post-implantation condition. Results: The surgical procedure was completed in all cases, with only minor intraoperative divergence from the CT-based planning and no postoperative complications. The average improvement of the SRT in quiet with the BB in comparison to the unaided condition was 36.25 dB. All the implanted subjects reached SRT values below 65 dB, indicating a better understanding in quiet, with 100% word recognition.

Auditory Training: Evidence for Neural Plasticity in Older Adults.

Improvements in digital amplification, cochlear implants, and other innovations have extended the potential for improving hearing function; yet, there remains a need for further hearing improvement in challenging listening situations, such as when trying to understand speech in noise or when listening to music. Here, we review evidence from animal and human models of plasticity in the brain's ability to process speech and other meaningful stimuli. We considered studies targeting populations of younger through older adults, emphasizing studies that have employed randomized controlled designs and have made connections between neural and behavioral changes. Overall results indicate that the brain remains malleable through older adulthood, provided that treatment algorithms have been modified to allow for changes in learning with age. Improvements in speech-in-noise perception and cognition function accompany neural changes in auditory processing. The training-related improvements noted across studies support the need to consider auditory training strategies in the management of individuals who express concerns about hearing in difficult listening situations. Given evidence from studies engaging the brain's reward centers, future research should consider how these centers can be naturally activated during training.

Improving Hearing Aid Function in Noisy Situations

Improving Hearing Aid Function in Noisy Situations

Modeling speech intelligibility in quiet and noise in listeners with normal and impaired hearing

The speech intelligibility index (SII) is an often used calculation method for estimating the proportion of audible speech in noise. For speech reception thresholds (SRTs), measured in normally hearing listeners using various types of stationary noise, this model predicts a fairly constant speech proportion of about 0.33, necessary for Dutch sentence intelligibility. However, when the SII model is applied for SRTs in quiet, the estimated speech proportions are often higher, and show a larger inter-subject variability, than found for speech in noise near normal speech levels [65 dB sound pressure level (SPL)]. The present model attempts to alleviate this problem by including cochlear compression. It is based on a loudness model for normally hearing and hearing-impaired listeners of Moore and Glasberg [(2004). Hear. Res. 188, 70-88]. It estimates internal excitation levels for speech and noise and then calculates the proportion of speech above noise and threshold using similar spectral weighting as used in the SII. The present model and the standard SII were used to predict SII values in quiet and in stationary noise for normally hearing and hearing-impaired listeners. The present model predicted SIIs for three listener types (normal hearing, noise-induced, and age-induced hearing loss) with markedly less variability than the standard SII.

Predicting consonant recognition in quiet for listeners with normal hearing and hearing impairment using an auditory model.

Contrary to listeners with normal hearing, listeners with high-frequency sensorineural hearing loss suffer especially from a poor consonant recognition. This is mainly attributed to the loss of audibility within high-frequency regions. In a former study [Jürgens and Brand, J. Acoust. Soc. Am. (submitted)] it was shown that consonant recognition rates in noise can be predicted well for normal-hearing listeners using an auditory model combined with a speech recognizer. The speech reception threshold (SRT) in noise could be predicted with an accuracy of 1–2 dB. In this study consonant recognition in quiet for normal-hearing and hearing-impaired listeners is investigated by regarding the individual absolute hearing threshold within the model. Observed and predicted psychometric functions of the consonant discrimination performance, consonant recognition rates of single consonants, and confusions are compared and discussed. The results show that the SRT in quiet can be predicted well for both normal-hearing and hearing-impaired listeners. Furthermore, the auditory model is modified to the signal processing of listeners with mild to moderate hearing impairment by, e.g., including a reduced dynamic compression, in order to investigate the influence on the predictions. [Work supported by DFG.]

Selecting Speech Tests to Measure Auditory Function

Selecting Speech Tests to Measure Auditory Function

A model with compression for estimating speech intelligibility in quiet and in noise

For speech reception thresholds (SRTs), measured in normally‐hearing listeners using various types of stationary noise, the Speech Intelligibility Index (SII, ANSI S3.5‐1997) model predicts a fairly constant speech proportion (of about 0.3) necessary for sentence intelligibility. For SRTs in quiet, the estimated speech proportions are often lower, and show a larger inter‐subject variability, than found for speech in noise near normal speech levels. This might be related to the fact that cochlear compression is larger at normal speech levels than near the threshold for speech in quiet. The SII model does not take this into account. The present model attempts to alleviate this problem by including cochlear compression. It is based on a loudness model for normally‐hearing and hearing‐impaired listeners [ANSI S3.4‐2007]. It estimates internal excitation levels of the speech, accounts for the compressed effective dynamic range of the internal speech signal, and calculates the proportion of speech above thresho...

Effects of Expansion Algorithms on Speech Reception Thresholds

Expansion is commonly used to reduce microphone noise and low-level environmental noises that can be annoying to hearing aid users. It may also improve or reduce the perception of low-level speech. This study assessed the impact of two expansion algorithms, single and multiple channel, on speech reception thresholds (SRT) with 10 hearing impaired listeners wearing hearing aids with ADRO processing. The single-channel algorithm suppressed sounds below 45 dB A, while the multiple-channel algorithm suppressed sounds below the long-term average spectrum of speech at either 55 or 45 dB SPL. The mean HINT SRTs in quiet were 39.4, 40.7, 40.6, and 41.8 dB A without expansion, with single-channel expansion, and with multiple-channel expansion at expansion thresholds of 45 and 55 dB SPL, respectively. The difference in mean SRT was only statistically significant between no expansion and multiple-channel expansion at a 55 dB SPL threshold. A regression analysis between the change in individual SRT for each expansion condition and pure tone average hearing loss showed no correlation. Our calculations indicate that only those with exceptionally good hearing will find microphone noise audible. The current practice of prescribing expansion algorithms based on hearing thresholds alone is questioned, and other rationales are discussed.

LIST and LINT: Sentences and numbers for quantifying speech understanding in severely impaired listeners for Flanders and the Netherlands

A Dutch sentence test (LIST) and a Dutch number test (LINT) have been developed and validated for the accurate measurement of speech reception thresholds (SRT) in quiet and in noise with severely hearing-impaired individuals and cochlear implant recipients in Flanders and the Netherlands. The LIST consists of 35 lists of 10 sentences of equal known difficulty uttered by a female speaker; while the LINT consists of 400 numbers (1–100) by two male and two female speakers. Normative values were determined at fixed S/N ratios and using the adaptive method (Plomp & Mimpen, ), yielding identical results for SRT and slope. For the LIST, average fitted SRTs were 27.1 (0.9) dB SPL in quiet and −7.8 dB (0.2) SNR in noise. In addition, the LIST in noise displayed a steep discrimination function (17%/dB) and good reliability (within-subject standard deviation=1.2 dB). For the LINT average fitted SRTs in quiet were 20.7 (0.9) dB SPL and about −9.0 dB SNR in noise. Again, the slopes of the performance intensity functions were relatively steep, i.e. 8.5%/dB in quiet and 15.2%/dB in noise, suggesting that the LINT is accurate and efficient and thus capable of reflecting subtle changes in performance. First data with cochlear implanted subjects show that both LIST and LINT are feasible and are capable of mapping a large range of hearing disabilities.

A model with compression for the estimation of speech intelligibility in quiet

The Speech Intelligibility Index (SII) is an often used calculation method for estimating the proportion of speech information available in noise. For speech reception thresholds (SRTs), measured in normal-hearing listeners using various types of stationary noise, this model predicts a fairly constant speech proportion (about 0.30) necessary for sentence intelligibility. However, when the SII model is applied for SRTs in quiet, the estimated speech proportions are often lower, and show a larger inter-subject variability, than found for speech in noise near the normal speech level (65 dB SPL). The present model attempts to alleviate this problem by including cochlear compression. It is based on a loudness model for normal-hearing and hearing-impaired listeners of Moore and Glasberg [Hear. Res. 188, 70–88 (2004)]. It estimates internal excitation levels of the speech and then calculates the proportion of speech above threshold using similar spectral weighting as used in the standard SII. The present model and the standard SII were used to predict SRTs in quiet for both normal-hearing and hearing-impaired listeners. The present model predicted a set of data for three listener types (normal hearing, noise-induced hearing loss, and age-induced hearing loss) with less variability than the standard SII.

Effects of age on speech understanding in normal hearing listeners: Relationship between the auditory efferent system and speech intelligibility in noise

Human listeners are able to listen to one voice in the midst of other conversations and background noise. Although the neural mechanisms for this process are not well understood, there is growing evidence that the medial olivocochlear (MOC) auditory efferent system located in the brainstem is involved in the detection of signals in noise, such as speech sounds, by modulating cochlear (inner ear) active physiological mechanisms. The present study examined MOC efferent (feedback) effects as revealed in distortion product otoacoustic emissions (DPOAEs) and effects of spatial separation for speech perception in background noise. Both spatial separation of speech in noise and contralateral suppression (CS) of DPOAE invoke neural mechanisms central to the inner ear. We sought to determine whether these tasks might be related and thereby represent involvement in the ability to listen to one voice in the midst of concurrent conversation and background noise; a situation in which elderly listeners have great difficulty. The Hearing in the Noise Test (HINT) [Nilsson, M., Soli, S.D., Sullivan, J.A., 1994. Development of the hearing in noise test for the measurement of speech reception thresholds in quiet and in noise. J. Acoust. Soc. Amer. 95, 1085–1099] was used to obtain release from masking (RFM) estimates of speech in noise. DPOAEs were used to measure effects of broadband noise introduced to the ear contralateral to the target ear (CS). Significant age effects were found in both domains. Significant correlations resulted between speech perception in noise (RFM) and the degree of CS of DPOAEs. RFM was significantly related only to age and CS at the DPOAE narrow-band frequency of 1–2 kHz; a frequency band critical for successful speech perception. These findings suggest that the MOC efferent system and neural mechanisms underlying RFM are related and contribute to sound source determination commonly referred to as the “cocktail party effect”.

The role of silent intervals for sentence intelligibility in fluctuating noise in hearing-impaired listeners

Fluctuating interfering noises are highly suitable for speech audiometry because of the large inter-individual variability in intelligibility results. This study explores the maximum duration of silent intervals in the masker as an important factor underlying sentence intelligibility in fluctuating noise. Three versions of speech-simulating fluctuating interfering noises based on the icra noises (Dreschler et al, ) were explored: The original noise which simulates one interfering speaker and contains pause durations up to two seconds, as well as two modified versions with pause durations limited to 250 ms and 62.5 ms, respectively. In addition, a stationary speech-shaped noise was used. Test-retest reliability as well as speech reception threshold (SRT) and speech intelligibility function slope were determined with hearing-impaired subjects. All fluctuating noises differentiated very well between subjects. Partial rank correlation analysis showed that SRTs in fluctuating noise with longest maximum pause durations mostly depended on SRTs in quiet. SRTs in fluctuating noises with smaller maximum pause durations correlated both with SRTs in quiet and in stationary noise.SumarioLos ruidos fluctuantes de interferencia son muy apropiados en logoaudiometría debido a la gran variabilidad inter-individuos en los resultados de inteligibilidad. Este estudio explora la duración máxima de intervalos de silencio en el enmascarador, como un importante factor subyacente en la inteligibilidad de frases en medio de ruido fluctuante. Se exploraron tres versiones de ruidos fluctuantes de interferencia simulando lenguaje, con base en los ruidos icra (Dreschler y col., 2001): el ruido original que simula la interferencia de un hablante y contiene pausas de hasta 2 segundos de duración, y también dos versiones modificadas con pausas de duración limitadas a 250 mseg y 62.5 mseg, respectivamente. Además, se utilizó un ruido estacionario moldeado como lenguaje. Se determinó la confiabilidad test-retest al igual que la pendiente de las funciones del SRT y la inteligibilidad del lenguaje, en sujetos hipoacúsicos. Todos los ruidos fluctuantes se diferenciaron muy bien entre los sujetos. Un análisis de correlación de rango parcial mostró que los SRT en ruido fluctuante con las duraciones más prolongadas de pausa máxima, dependían del SRT en silencio. Los SRT en ruido fluctuante con duraciones menores de pausa máxima, correlacionaron tanto con los SRT en silencio como con el ruido estacionario.

Perceptual consequences of normal and abnormal peripheral compression: Potential links between psychoacoustics and speech perception

Cochlear damage can lead to a reduction in the overall amount of peripheral auditory compression, presumably due to outer hair cell (OHC) loss or dysfunction. The perceptual consequences of functional OHC loss include loudness recruitment and reduced dynamic range, poorer frequency selectivity, and poorer effective temporal resolution. These in turn may lead to a reduced ability to make use of spectral and temporal fluctuations in background noise when listening to a target sound, such as speech. We tested the effect of OHC function on speech reception in hearing-impaired listeners by comparing psychoacoustic measures of cochlear compression and sentence recognition in a variety of noise backgrounds. In line with earlier studies, we found weak (nonsignificant) correlations between the psychoacoustic tasks and speech reception thresholds in quiet or in steady-state noise. However, when spectral and temporal fluctuations were introduced in the masker, speech reception improved to an extent that was well predicted by the psychoacoustic measures. Thus, our initial results suggest a strong relationship between measures of cochlear compression and the ability of listeners to take advantage of spectral and temporal masker fluctuations in recognizing speech. [Work supported by NIH Grants Nos. R01DC03909, T32DC00038, and R01DC00117.]

Bilateral bone-anchored hearing aids (BAHAs): an audiometric evaluation.

Since the technique to implant bone-anchored hearing aids (BAHAs) with the use of osseointegrated implants was developed in 1977, more than 15,000 patients have been fitted with BAHAs worldwide. Although the majority have bilateral hearing loss, they are primarily fitted unilaterally. The main objective of this study was to reveal benefits and drawbacks of bilateral fitting of BAHAs in patients with symmetric or slight asymmetric bone-conduction thresholds. The possible effects were divided into three categories: hearing thresholds, directional hearing, and binaural hearing. Prospective study of 12 patients with bilateral BAHAs. Baseline audiometry, directional hearing, speech reception thresholds in quiet and in noise, and binaural masking level difference were tested when BAHAs were fitted unilaterally and bilaterally. Eleven of the 12 patients used bilateral BAHAs on a daily basis. Tests performed in the study show a significant improvement in sound localization with bilateral BAHAs; the results with unilateral fitting were close to the chance level. Furthermore, with bilateral application, the improvement of the speech reception threshold in quiet was 5.4 dB. An improvement with bilateral fitting was also found for speech reception in noise. Overall, the results with bilateral fitted BAHAs were better than with unilaterally fitted BAHA; the benefit is not only caused simply by bilateral stimulation but also, to some extent, by binaural hearing. Bilateral BAHAs should be considered for patients with bilateral hearing loss otherwise suitable for BAHAs.