Speech Recognition Threshold In Noise Research Articles

Equivalence and test–retest reliability of Tulu sentence lists for measuring speech recognition threshold in noise among individuals with sensorineural hearing loss

BackgroundThe difficulty in understanding speech becomes worse in the presence of background noise for individuals with sensorineural hearing loss. Speech-in-noise tests help to assess this difficulty. Previously, the Tulu sentence lists have been assessed for their equivalency to measure speech recognition threshold in noise among individuals with normal hearing. The present study aimed to determine the equivalence and test–retest reliability of Tulu sentence lists for measuring speech recognition threshold in noise among individuals with sensorineural hearing loss.ResultsThe SNR-50 was measured for 13 sentence lists in 20 Tulu-speaking individuals with mild to moderate sensorineural hearing loss. Retesting was done by administering all lists to eight participants after an average of 25.25 days (SD = 19.44). Friedman test was administered to check for the list equivalency. Intraclass correlation coefficient was measured to assess test–retest reliability. A regression analysis was performed to understand the influence of pure-tone average on SNR-50. A Kruskal–Wallis test was administered to check the statistical significance of the SNR-50 obtained across different configurations and degrees of hearing loss. Nine of the 13 Tulu sentence lists (lists 2, 4, 5, 6, 9, 10, 11, 12, and 13) were equivalent in individuals with sensorineural hearing loss. The mean SNR-50 for these nine lists was 1.13 dB (SD = 2.04 dB). The test–retest reliability was moderate (ICC = 0.727). The regression analysis showed that a pure-tone average accounted for 24.7% of the variance in SNR-50 data (p = 0.026). Individuals with mild to moderate hearing loss obtained the worst SNR-50, followed by mild and high-frequency hearing loss.ConclusionNine Tulu sentence lists are equivalent and reliable and can be used to measure speech recognition threshold in noise among individuals with sensorineural hearing loss who are Tulu speakers.

Evaluating the Compatibility of the Digit-in-Noise Test with Hearing Screening in Individuals with Intellectual Disabilities: A Pilot Study.

Hearing impairment among adults with intellectual disability (ID) is notably prevalent yet frequently underdiagnosed due, in part, to the challenges associated with traditional hearing screening methods in this population. This study explores the effectiveness of the Digit-in-Noise (DIN) test as a viable alternative for hearing screening within natural settings and with familiar personnel. A total of 16 Hebrew-speaking adults with ID were recruited from supported employment programs, 10 of whom completed the study. The DIN test, which was administered in a daily environment using a simple digital device, evaluated the speech recognition threshold in noise. Results indicated that while some participants performed comparably to typically developing individuals, others showed varying levels of hearing thresholds, suggesting diverse auditory capabilities within the ID population. This pilot study confirms that the DIN test can be feasibly integrated into routine care settings, offering a friendly and accessible method for assessing hearing abilities in adults with ID. The findings advocate for the broader adoption of and potential modifications to the DIN Test to enhance its applicability and inclusiveness, thereby improving diagnostic accuracy and subsequent auditory care for this underserved population.

Predicting Matrix Test Effectiveness for Evaluating Auditory Performance in Noise Using Pure-Tone Audiometry and Speech Recognition in Quiet in Cochlear Implant Recipients

Introduction: Auditory performance in noise of cochlear implant recipients can be assessed with the adaptive Matrix test (MT); however, when the speech-to-noise ratio (SNR) exceeds 15 dB, the background noise has any negative impact on the speech recognition. Here, we aim to evaluate the predictive power of aided pure-tone audiometry and speech recognition in quiet and establish cut-off values for both tests that indicate whether auditory performance in noise can be assessed using the Matrix sentence test in a diffuse noise environment. Methods: Here, we assessed the power of pure-tone audiometry and speech recognition in quiet to predict the response to the MT. Ninety-eight cochlear implant recipients were assessed using different sound processors from Advanced Bionics (n = 56) and CochlearTM (n = 42). Auditory tests were performed at least 1 year after cochlear implantation or upgrading the sound processor to ensure the best benefit of the implant. Auditory assessment of the implanted ear in free-field conditions included: pure-tone average (PTA), speech discrimination score (SDS) in quiet at 65 dB, and speech recognition threshold (SRT) in noise that is the SNR at which the patient can correctly recognize 50% of the words using the MT in a diffuse sound field. Results: The SRT in noise was determined in 60 patients (61%) and undetermined in 38 (39%) using the MT. When cut-off values for PTA <36 dB and SDS >41% were used separately, they were able to predict a positive response to the MT in 83% of recipients; using both cut-off values together, the predictive value reached 92%. Discussion: As the pure-tone audiometry is standardized universally and the speech recognition in quiet could vary depending on the language used; we propose that the MT should be performed in recipients with PTA <36 dB, and in recipients with PTA >36 dB, a list of Matrix sentences at a fixed SNR should be presented to determine the percentage of words understood. This approach should enable clinicians to obtain information about auditory performance in noise whenever possible.

The Effect of Hemodialysis on Spectral and Temporal Processing Abilities and Speech Perception in Noise among Individuals with Chronic Kidney Disease

Introduction: The effect of chronic kidney disease (CKD) on hearing is well documented in the literature. Several studies have investigated the effect of hemodialysis on the peripheral auditory system among individuals with CKD. However, studies investigating the effect of hemodialysis on speech perception and auditory processing abilities are limited. The present study investigated the effect of hemodialysis on few auditory processing abilities and speech perception in noise among adults with CKD. Methods: A total of 25 adults with CKD undergoing hemodialysis regularly participated in the study. Spectral ripple discrimination threshold (SRDT), gap detection threshold (GDT), amplitude-modulation detection threshold (AMDT), and speech recognition threshold in noise (SRTn) were measured before and after hemodialysis. Paired samples “t” test was carried out to investigate the effect of hemodialysis on thresholds. Results: Results showed a significant improvement for SRDT, GDT, AMDT, and SRTn after hemodialysis among individuals with CKD. Discussion: Hemodialysis showed a positive effect on speech perception in noise and auditory processing abilities among individuals with CKD.

Evaluation of Subtle Auditory Impairments with Multiple Audiological Assessments in Normal Hearing Workers Exposed to Occupational Noise.

Recent studies involving guinea pigs have shown that noise can damage the synapses between the inner hair cells and spiral ganglion neurons, even with normal hearing thresholds-which makes it important to investigate this kind of impairment in humans. The aim was to investigate, with multiple audiological assessments, the auditory function of normal hearing workers exposed to occupational noise. Altogether, 60 workers were assessed (30 in the noise-exposure group [NEG], who were exposed to occupational noise, and 30 in the control group [CG], who were not exposed to occupational noise); the workers were matched according to age. The following procedures were used: complete audiological assessment; speech recognition threshold in noise (SRTN); speech in noise (SN) in an acoustic field; gaps-in-noise (GIN); transient evoked otoacoustic emissions (TEOAE) and inhibitory effect of the efferent auditory pathway; auditory brainstem response (ABR); and long-latency auditory evoked potentials (LLAEP). No significant difference was found between the groups in SRTN. In SN, the NEG performed worse than the CG in signal-to-noise ratio (SNR) 0 (p-value 0.023). In GIN, the NEG had a significantly lower percentage of correct answers (p-value 0.042). In TEOAE, the NEG had smaller amplitude values bilaterally (RE p-value 0.048; LE p-value 0.045) and a smaller inhibitory effect of the efferent pathway (p-value 0.009). In ABR, the NEG had greater latencies of wave V (p-value 0.017) and interpeak intervals III-V and I-V in the LE (respective p-values: 0.005 and 0.04). In LLAEP, the NEG had a smaller P3 amplitude bilaterally (RE p-value 0.001; LE p-value 0.002). The NEG performed worse than the CG in most of the assessments, suggesting that the auditory function in individuals exposed to occupational noise is impaired, even with normal audiometric thresholds.

OLSA level control in monaural speech audiometry in background noise for the evaluation of the CI fitting result

Speech audiometry measurements under the influence of background noise are a fundamental part of evaluating the outcome of hearing care. As yet far, there are no recommendations for selecting a suitable method for adaptive speech audiometry measurements in background noise in cochlear implant (CI) care, so either the choice the adaptive level change of the speech signal (S) with constant noise (N) or the adaptive level change of N with constant S. Do the measurement results of the monaural speechrecognition threshold in noise (SRT) with the Oldenburg Sentence Test (OLSA) depend on the choice of level control? A total of 50 series of measurements with OLSA in noise and the Freiburg speech intelligibility test in quiet (FBE) on middle-aged CIpatients from clinical routine. There is no significant difference in the measurement results with different level controls when the SRT is less than 5 [Formula: see text]. Below 55 % monosyllabic intelligibility in quiet, the SRT in noise becomes greater than 5 [Formula: see text]. From a clinical, audiological and methodological point of view, it is advisable to carry out the adaptive monaural speech intelligibility measurement with a constant speech signal at 65 [Formula: see text].

The French MBAA2 sentence recognition in noise test for cochlear implant users

Objective The “Marginal benefit from acoustic amplification” version 2 (MBAA2) sentence test has been used in France in the routine evaluation of cochlear implant (CI) users for 20 years. Here we present four studies that characterise and validate the test, and compare it with the French matrix sentence test. Design and sample An analytic method was developed to obtain speech recognition threshold in noise (SNR50) from testing at a fixed signal to noise ratios (SNRs). Speech recognition was measured at several fixed SNRs in 18 normal-hearing listeners and 15 CI listeners. Then, the test–retest reliability of the MBAA2 was measured in an additional 15 CI listeners. Finally, list equivalence was evaluated in eight CI listeners. Results The MBAA2 test produced lower SNR50s and SNR50s were obtained in more CI listeners than with the French matrix test. For the MBAA2, the standard deviation of test–retest differences in CI listeners was around 1 dB SNR. Three lists had deviant difficulty and nine low item-to-total correlations. Conclusions We propose to reduce the number of MBAA2 test lists to reduce variability. The MBAA2 test has high test–retest reliability for percent correct and SNR50, and is suitable for the assessment of cochlear implant patients.

Influence of Tinnitus-Control Sound Stimuli on Auditory Spectral and Temporal Resolution and Speech Perception in Hearing Aid Users

Background and Objectives: Hearing aids (HAs) with built-in sound generators can alleviate the discomfort of tinnitus in individuals with tinnitus and impaired hearing. However, it is unknown how tinnitus-control sound (TCS) affects speech perception in HA users. Therefore, this study aimed to evaluate the effect of HA TCS on auditory spectral resolution, temporal resolution, and speech perception in individuals with tinnitus and impaired hearing. Materials and Methods: The subjects were 13 elderly listeners (62.38±8.44 years, seven males, six females) with tinnitus and impaired hearing who had been using a receiver-in-canal HA with a built-in sound generator in everyday life for more than 3 months. The following psychoacoustic measurements were performed: spectral-ripple discrimination (SRD), temporal modulation detection (TMD), and speech recognition threshold in noise. The results obtained with HA-only and HA plus TCS conditions were compared. Results: There were no significant differences in SRD and TMD between the HA-only and HA plus TCS conditions (p&gt;0.05). However, the HA plus TCS conditions were associated with worse speech recognition than the HA-only conditions (p=0.027). Conclusions: TCS constrains speech perception in noise in individuals with tinnitus and impaired hearing, implying that the TCS introduces additional noise to existing tinnitus. Therefore, we recommend that individuals with tinnitus who use a HA with a built-in sound generator should turn off the sound generator in daily life, especially in noisy environments. (J Clinical Otolaryngol 2021;32:202-211)

Temporal processing, spectral processing, and speech perception in noise abilities among individuals with chronic kidney disease undergoing hemodialysis

Background In the literature, the effect of chronic kidney disease on the peripheral auditory system has been well documented. But studies investigating the effect of chronic kidney disease on speech perception and auditory processing abilities are limited. Aims/objectives The present study investigated the effect of chronic kidney disease on different auditory processing tasks and speech perception in noise among adults. Material and methods A total of 28 adults participated in the study. Group 1 included 14 individuals with chronic kidney disease undergoing hemodialysis, and Group 2 included 14 individuals with no known kidney complications. Amplitude modulation detection threshold, gap detection threshold, spectral ripple discrimination threshold, and speech recognition threshold in noise were measured. Independent samples t-test was carried out to investigate whether mean thresholds are significantly different between groups. Results Results showed poorer gap detection threshold, amplitude modulation detection threshold, spectral ripple discrimination threshold, and speech recognition threshold in noise among individuals with chronic kidney disease compared to individuals with no known kidney complications. Conclusions The present study showed poorer auditory processing and speech perception abilities in individuals with chronic kidney disease.

Development and Validation of Tulu Sentence Lists to Test Speech Recognition Threshold in Noise

Introduction We aimed to develop sentence lists in Tulu language to measure speech recognition thresholds (SRTs) in noise and verify the equivalence of the developed lists in noise among individuals with normal hearing. Methods This cross-sectional study was conducted in three phases; first, the developmental phase, collection, and development of the sentence material in the Tulu language were carried out. Sentences rated highly familiar/familiar and highly natural/natural by 80% of the raters were considered for the next phase. In the second phase, 22 sentence lists were prepared, with each list containing ten sentences of equal difficulty level in noise. The difficulty level was matched mainly based on the similarity (±1 standard deviation [SD]) of signal-to-noise ratio 50 (SNR-50), the slope of the sentences, the number of content words, and phonemes. The third phase evaluated the equivalency of developed sentence lists. Sixty-two native Tulu speakers with normal hearing sensitivity, aged between 18 and 39 years, participated. Of these 62 participants, twelve were recruited for the first phase, 20 individuals participated in the second phase, and 30 participated in the third phase. Results Thirteen sentence lists were equivalent and were a reliable measure of SNR-50 in native speakers of Tulu who have hearing sensitivity within normal limits. Using the sentence scoring method, the average SNR-50 of these sentence lists was − 4.19 dB with a SD of 0.21 dB. The developed sentences also had less within-subject variability than between-subject variability. Conclusions These 13 equivalent sentence lists provide a valid and reliable tool to measure the SRT in noise in native Tulu speakers with hearing sensitivity within normal limits.

Development of a Smartphone-Based Digits-in-Noise Test in Korean: a Hearing Screening Tool for Speech Perception in Noise.

BackgroundThe digits-in-noise (DiN) test is a speech-in-noise test to measure speech recognition threshold in noise adaptively. Herein, we aimed to develop the Korean version of the DiN test to provide a useful hearing screening tool for clinical as well as research purposes.MethodSpoken monosyllabic digits from 0 to 9 were recorded by a female speaker. The test list was constructed such that each digit was placed in three different positions. An optimization procedure was conducted to equate the audibility of each digit. After the optimization, the smartphone application for the Korean DiN (K-DiN) test was developed. For the adaptive measurement procedure, 180 new DiN triplets separated into six lists of 30 were created. Mean speech recognition threshold values for each list and session were measured to examine the test-retest and training effects of the test materials. In addition, speech recognition threshold values measured by different devices were compared to determine whether the speech recognition threshold levels differed.ResultsOptimization results showed that the mean speech recognition threshold and slope were −11.55 dB signal-to-noise ratio and 10.21%/dB, respectively, which are comparable to levels shown in different-language versions of the DiN test. The results of the test-retest and training effects revealed no significant differences among the test sessions and lists. Additionally, the mean speech recognition threshold values measured by four different devices were not different, indicating the reliability of the test materials.ConclusionWe believe this study is the first to attempt to develop a K-DiN test. Our results indicate that this test can be used as a potentially reliable hearing screening tool.

Effect of Audibility and Suprathreshold Deficits on Speech Recognition for Listeners With Unilateral Hearing Loss.

Objectives:We examined the influence of impaired processing (audibility and suprathreshold processes) on speech recognition in cases of sensorineural hearing loss. The influence of differences in central, or top-down, processing was reduced by comparing the performance of both ears in participants with a unilateral hearing loss (UHL). We examined the influence of reduced audibility and suprathreshold deficits on speech recognition in quiet and in noise.Design:We measured speech recognition in quiet and stationary speech-shaped noise with consonant–vowel–consonant words and digital triplets in groups of adults with UHL (n = 19), normal hearing (n = 15), and bilateral hearing loss (n = 9). By comparing the scores of the unaffected ear (UHL+) and the affected ear (UHL−) in the UHL group, we were able to isolate the influence of peripheral hearing loss from individual top-down factors such as cognition, linguistic skills, age, and sex.Results:Audibility is a very strong predictor for speech recognition in quiet. Audibility has a less pronounced influence on speech recognition in noise. We found that, for the current sample of listeners, more speech information is required for UHL− than for UHL+ to achieve the same performance. For digit triplets at 80 dBA, the speech recognition threshold in noise (SRT) for UHL− is on average 5.2 dB signal to noise ratio (SNR) poorer than UHL+. Analysis using the speech intelligibility index (SII) indicates that on average 2.1 dB SNR of this decrease can be attributed to suprathreshold deficits and 3.1 dB SNR to audibility. Furthermore, scores for speech recognition in quiet and in noise for UHL+ are comparable to those of normal-hearing listeners.Conclusions:Our data showed that suprathreshold deficits in addition to audibility play a considerable role in speech recognition in noise even at intensities well above hearing threshold.

Effects of electrode deactivation on speech recognition in multichannel cochlear implant recipients

Objectives: The objective of the current study is to evaluate how speech recognition performance is affected by the number of active electrodes that are turned off in multichannel cochlear implants. Several recent studies have demonstrated positive effects of deactivating stimulation sites based on an objective measure in cochlear implant processing strategies. Previous studies using an analysis of variance have shown that, on average, cochlear implant listeners’ performance does not improve beyond eight active electrodes. We hypothesized that using a generalized linear mixed model would allow for better examination of this question.Methods: Seven peri- and post-lingual adult cochlear implant users (eight ears) were tested on speech recognition tasks using experimental MAPs which contained either 8, 12, 16 or 20 active electrodes. Speech recognition tests included CUNY sentences in speech-shaped noise, TIMIT sentences in quiet as well as vowel (CVC) and consonant (CV) stimuli presented in quiet and in signal-to-noise ratios of 0 and +10 dB.Results: The speech recognition threshold in noise (dB SNR) significantly worsened by approximately 2 dB on average as the number of active electrodes was decreased from 20 to 8. Likewise, sentence recognition scores in quiet significantly decreased by an average of approximately 12%.Discussion/conclusion: Cochlear implant recipients can utilize and benefit from using more than eight spectral channels when listening to complex sentences or sentences in background noise. The results of the current study suggest a conservative approach for turning off stimulation sites is best when using site-selection procedures.

Association of Auditory Steady State Responses with Perception of Temporal Modulations and Speech in Noise

Amplitude modulations in the speech convey important acoustic information for speech perception. Auditory steady state response (ASSR) is thought to be physiological correlate of amplitude modulation perception. Limited research is available exploring association between ASSR and modulation detection ability as well as speech perception. Correlation of modulation detection thresholds (MDT) and speech perception in noise with ASSR was investigated in twofold experiments. 30 normal hearing individuals and 11 normal hearing individuals within age range of 18–24 years participated in experiments 1 and 2, respectively. MDTs were measured using ASSR and behavioral method at 60 Hz, 80 Hz, and 120 Hz modulation frequencies in the first experiment. ASSR threshold was obtained by estimating the minimum modulation depth required to elicit ASSR (ASSR-MDT). There was a positive correlation between behavioral MDT and ASSR-MDT at all modulation frequencies. In the second experiment, ASSR for amplitude modulation (AM) sweeps at four different frequency ranges (30–40 Hz, 40–50 Hz, 50–60 Hz, and 60–70 Hz) was recorded. Speech recognition threshold in noise (SRTn) was estimated using staircase procedure. There was a positive correlation between amplitude of ASSR for AM sweep with frequency range of 30–40 Hz and SRTn. Results of the current study suggest that ASSR provides substantial information about temporal modulation and speech perception.

The Danish hearing in noise test

Objective: A Danish version of the hearing in noise test (HINT) has been developed and evaluated in normal-hearing (NH) and hearing-impaired (HI) listeners. The speech material originated from Nielsen & Dau (2009) where a sentence-based intelligibility equalization method was presented. Design: In the present study, the speech material was evaluated for naturalness and a subset of sentences selected. The new sentence lists were validated, and after three weeks retested. An additional experiment investigated how recollection of sentences affected the listeners’ performance. Study sample: 16 NH and 16 HI listeners participated in the validation and retest. Twelve HI listeners participated in the experiment on recollection. Results: The average speech recognition threshold in noise (SRTN) for the NH listeners was −2.52 dB, with an overall standard deviation of 0.87 dB. The within-subject standard deviation was similar for the NH and the HI listeners. In the retest, the SRTN decreased by 0.4 dB in both groups. Conclusions: The Danish HINT consists of 10 test lists and three practice lists each containing 20 sentences. The validation results are comparable to those of other versions of HINT. The test seems equally reliable for NH and HI listeners. After three weeks, reliable results can be obtained when sentence lists are reused with the same listeners.SumarioObjectivo: Se ha desarrollado una versión danesa del HINT en sujetos normoyentes (NH) y en hipoacúsicos (HI). Se presentó el material del habla originado por Nielsen & Dau (2009) en donde el método de ecualización fue basado en la inteligibilidad de una oración. Diseño: Se evaluó la naturalidad del material del habla y un subgrupo seleccionado de oraciones. Las nuevas listas de oraciones se validaron y después de tres semanas se re-examinaron. Un experimento adicional investigó cómo afectaba el desempeño de los oyentes la recolección de las oraciones. Muestra: 16 NH y 16 HI participaron en la validación y la re-examinación. Doce HI participaron en la recolección del experimento. Resultados: El umbral promedio del reconocimiento del habla en ruido (SRTN) para los participantes NH fue -2.52 dB con un desviación estándar general de 0.87 dB. La desviación estándar intra-sujeto fue similar para los participantes NH y los HI. En la re-examinación el SRTN disminuyó en 0.4dB en ambos grupos. Conclusiones: El HINT danés consta de 10 listas y tres listas de práctica; cada una contiene 20 oraciones. La validación de resultados es comparable a aquella de otra versión de HINT. La prueba parece ser igualmente confiable para personas NH que para HI. Después de tres semanas los SRTN disminuyeron muy ligeramente cuando las listas de oraciones fueron usadas en los mismos oyentes.

Speech recognition threshold in noise for 100 Japanese monosyllables in &quot;Familiarity-controlled word lists 2003 (FW03)&quot;

Speech recognition threshold in noise for 100 Japanese monosyllables in &quot;Familiarity-controlled word lists 2003 (FW03)&quot;

Development of a Danish speech intelligibility test

A Danish speech intelligibility test for assessing the speech recognition threshold in noise (SRTN) has been developed. The test consists of 180 sentences distributed in 18 phonetically balanced lists. The sentences are based on an open word-set and represent everyday language. The sentences were equalized with respect to intelligibility to ensure uniform SRTN assessments with all lists. In contrast to several previously developed tests such as the hearing in noise test (HINT) where the equalization is based on scored (objective) measures of word intelligibility, the present test used an equalization method based on subjective assessments of the sentences. The new equalization method is shown to create lists with less variance between the SRTNs than the traditional method. The number of sentence levels included in the SRTN calculation was also evaluated and differs from previous tests. The test was verified with 14 normal-hearing listeners; the overall SRTN lies at a signal-to-noise ratio of −3.15 dB with a standard deviation of 1.0 dB. The list-SRTNs deviate less than 0.5 dB from the overall mean.

The Finnish speech in noise test for assessing sensorineural hearing loss.

A computerized adaptive Finnish speech in noise test was developed recently. As part of the test's evaluation process 172 patients with sensorineural hearing loss including 20 normally hearing subjects were measured using pure-tone audiometry, speech recognition threshold in noise (SRTN) test and conventional speech audiometry without background noise. As anticipated, sensorineural hearing loss yielded an elevation of SRTN although individual differences were considerable. The SRTN test was accurate as the absolute difference between individual repeated SRTNs was, on average, 1.5 dB (SD 1.5 dB) when the range of possible test values is from approximately -12 to +20 dB. On average, the learning effect was 0.5 dB.

Finnish speech in noise test: long-term reproducibility.

A computerized adaptive Finnish speech in noise test was developed recently. As part of the test's evaluation process the long-term stability of speech recognition threshold in noise (SRTN) was determined. The non-operated ears of 164 stapes surgery patients were assessed preoperatively and at 1, 7 and 19 months postoperatively. Short-term and long-term repeatability were equal. The absolute intraindividual differences were 1.5 dB on average.

New Speech-in-Noise Test in Different Types of Hearing Impairment

A new test was developed to assess speech recognition in noise. The test was designed to be run in a personal computer supplied with a sound card. One thousand disyllabic test words and noise were stored in digitized form on the hard disk of the computer. The measure given by this test is speech recognition threshold in noise (SRTN) corresponding to 50% recognition. The present series of 180 cases with various hearing impairments and 39 controls were examined with speech-in-noise test and conventional audiometry. In keeping with earlier studies, the SRTN turned out to be significantly elevated in cases with sensorineural hearing impairment; this elevation was related to the grade of hearing impairment. On the other hand, no essential difference was seen between the SRTN values of subjects with mixed hearing impairment and persons with normal hearing.