Cortical electric response audiometry hearing threshold estimation: accuracy, speed, and the effects of stimulus presentation features

OBJECTIVES: A number of stimulus presentation features of the tone burst-evoked N1-P2 cortical response were investigated to identify any advantage over simple stimulation when the test is used for hearing threshold estimation. The speed of establishing objective thresholds at 1, 3, and 8 kHz in both ears was also measured in what was designed to be an efficient test protocol, together with the precision of the threshold estimates with reference to subjects' conventional audiograms. DESIGN: Twenty-four volunteer subjects were recruited and tested by both behavioral and electrophysiological methods. A low-intensity, 3-kHz stimulus was used when the stimulus features were studied. The parameter was the N1-P2 amplitude. RESULTS: Changing the side of presentation (randomly or by alternating ears), varying the interstimulus interval and inserting a 10-second recovery period midway though an averaging run had no demonstrable effect on response amplitude, both individually or in combination, contrary to earlier reports. Establishing the 6 threshold estimates took an average 20.6 minutes. The mean error in the N1-P2 threshold estimate was 6.5 dB, with no significant effect of frequency. After correcting for this bias, 94% of individual threshold estimates were within 15 dB of the behavioral threshold and 80% were within 10 dB. CONCLUSIONS: This study suggests that cortical electric response audiometry has a performance that is as good as or better than the auditory brain stem response for threshold estimation in adults and that sophisticated stimulation techniques do not appear to be required. An efficient test protocol that automates many laborious tasks reduces the test time to less than half that previously reported in the literature for this response.     

Stimulus characteristics which lessen the impact of threshold fine structure on estimates of hearing status

When hearing thresholds are measured with high-frequency resolution there is a pseudo-periodic variation in thresholds across frequency of up to 15-20dB. This variation is called threshold fine structure (previously referred to as threshold microstructure). Consequently, estimates of auditory status based on threshold measures can depend greatly on the specific frequency evaluated. The impact of threshold fine structure on the prediction of auditory status was examined by measuring detection thresholds of pure tones (providing an indication of threshold fine structure) and comparing them with thresholds obtained using linear sweeps, sinusoidally frequency modulated tones, and narrow-band noise. Spontaneous otoacoustic emissions (SOAEs) were also obtained to confirm the established relationship between threshold fine structure and SOAEs. Thresholds obtained using linear sweeps and narrow-band noise provided stable threshold estimates indicating that such threshold estimates were less influenced by threshold fine structure. Consequently, thresholds obtained with these stimuli may provide estimates of cochlear status less dependent of the exact frequency being evaluated, permitting better prediction of performance on other psychoacoustic measures (such as cochlear tuning and loudness perception) and the properties of their more objective measures (such as otoacoustic emissions).     

Effects of sensorineural hearing loss and personal hearing AIDS on cortical event-related potential and behavioral measures of speech-sound processing

OBJECTIVE: To systematically investigate the combined effects of sensorineural hearing loss and prescribed personal hearing aid(s) on cortical event-related potentials (ERPs) (waves N1, MMN, N2b, and P3b) and their related behavioral measures of discrimination (d-prime sensitivity and reaction time) to the speech sounds /ba/ and /da/ presented at 65 and 80 dB peak-to-peak equivalent SPL. DESIGN: Cortical ERPs were recorded to /ba/ and /da/ speech stimuli presented at 65 and 80 dB peak-to-peak equivalent SPL from 20 normal-hearing adults and 14 adults with sensorineural hearing losses. The degree of sensorineural impairment at 1000 to 2000 Hz ranged from moderate losses (50 to 74 dB HL) to severe-profound losses (75 to 120 dB HL). The speech stimuli were presented in an oddball paradigm and cortical ERPs were recorded in both active and passive listening conditions at both stimulus intensities. The adults with hearing impairments were tested in the unaided and aided conditions at each stimulus intensity. Electroacoustic and real-ear testing was performed on each subject's hearing aid(s) before electrophysiology testing to ensure that the hearing aids were functioning at the time of testing. RESULTS: The use of personal hearing aids substantially improved the detectability of all the cortical ERPs and behavioral d-prime performance scores at both stimulus intensities. This was especially true for individuals with severe-profound hearing losses. At 65 dB SPL, mean ERP amplitudes and d-prime sensitivity scores were all significantly higher or better in the aided versus unaided condition. At 80 dB SPL, only the N1 amplitudes and d-prime sensitivity scores were significantly better in the aided condition. Even though the majority of the hearing-impaired subjects showed increased amplitudes, decreased latencies, and better waveform morphology in the aided condition, the amount of response change (improvements) seen in these measures showed considerable variability across subjects. When compared with the responses obtained from the normal-hearing subjects, both hearing-impaired groups had significantly prolonged aided RT latencies at both stimulus intensities and N2b latencies at the higher stimulus intensities. CONCLUSIONS: These results suggest that hearing-impaired individuals' brains process speech stimuli with greater accuracy and in a more effective manner when these individuals use their personal hearing aids. This is especially true at the lower stimulus intensity. The effects of sensorineural hearing loss and personal hearing aids on cortical ERPs and behavioral measures of discrimination are dependent on the degree of sensorineural loss, the intensity of the stimuli, and the level of cortical auditory processing that the response measure is assessing. The possible clinical significance of these cortical ERP and behavioral findings is discussed.     

Effects of sensorineural hearing loss on cortical event-related potential and behavioral measures of speech-sound processing

OBJECTIVE: To investigate systematically the effects of sensorineural hearing loss on cortical event-related potentials (ERPs) N1, MMN, N2 and P3 and their associated behavioral measures (d' sensitivity and reaction time) to the speech sounds /ba/ and /da/ presented at 65 and 80 dB ppe SPL. DESIGN: Cortical ERPs were recorded to /ba/ and /da/ speech stimuli presented at 65 and 80 dB ppe SPL from 20 normal-hearing adults and 20 adults who are hearing impaired. The degree of sensorineural impairments at 1000 to 2000 Hz ranged from mild losses (defined as 25 to 49 dB HL) to severe/profound losses (75 to 120 dB HL). The speech stimuli were presented in an oddball paradigm and the cortical ERPs were recorded in both active and passive listening conditions for each stimulus intensity. RESULTS: Both ERP amplitudes and behavioral discrimination (d') scores were lower for listeners with sensorineural hearing loss than for those with normal hearing. However, these differences in response strength were evident only for those listeners whose average hearing loss at 1000 to 2000 Hz exceeded 60 dB HL for the lower intensity stimuli and exceeded 75 dB HL for the higher intensity stimuli. In contrast, prolongations in the ERP and behavioral latencies, relative to responses from normal-hearing subjects, began with even mild (25 to 49 dB HL) threshold elevations. The amplitude and latency response changes that occurred with sensorineural hearing loss were significantly greater for the later ERP peaks (N2/P3) and behavioral discrimination measures (d' and RT) in comparison with earlier (N1, MMN) responses. CONCLUSIONS: The results indicate that latency measures are more sensitive indicators of the early effects of decreased audibility than are response strength (amplitude, d' or percent correct) measures. Sensorineural hearing loss has a greater impact on higher level or "nonsensory" cortical processing in comparison with lower level or "sensory" cortical processing. Possible physiologic mechanisms within the cortex that may be responsible for these response changes are presented. Lastly, the possible clinical significance of these ERP and behavioral findings is discussed.     

鸡40Hz听觉相关电位记录方法及反应阈正常值

为能在同一系统内同时探讨多项测试条件和参数对鸡４０Ｈｚ听觉相关电位记录结果的影响，采用正交试验法为实验模型，对短音的升／降时间，平台时间，滤波下降和，滤波上限等四个因素进行筛选，以获得最佳的测试条件。结果发现，短音的升／降时间与平台时间为２－１－２周期，滤波范围为２０－７０Ｈｚ时测试结果最佳。     

The true threshold of the slow nystagmic component-L

The fast component of nystagmus begins where the slow component stops, at the point called the threshold of the fast component R. The fast component should last until the eye is brought back into the position of azimuth zero, where the slow component begins anew. This point can be called the threshold of the slow component L. So the fast component has a span from R to L and is presented as a side of a triangle r. An additional corrective procedure in electronystagmography is suggested to avoid failures and to define the true position of L. This is the way to correct the false information on nystagmic elements and to learn the unknown features of the fast component.     

The measurement of performance asymmetries with dichotic stimulus presentation

The failure to include only relevant observations in the assessment of laterality has resulted in a proliferation of post hoc attempts to "correct" laterality measures influenced by "overall performance level." The inclusion of information from trials in which both ears were either correct or in error contaminates the laterality measure (not overall performance per se). The use of single correct trial information obviates the need for adjusting laterality measures and lends itself to standard statistical procedures.     

Speech evoked cortical potentials: effects of age and stimulus presentation rate

We examined the effects of stimulus complexity and stimulus presentation rate in ten younger and ten older normal-hearing adults. A 1 kHz tone burst as well as a speech syllable were used to elicit the N1 -P2 complex. Three different interstimulus intervals (ISI) were used (510, 910, and 1510 msec). When stimuli were presented at the medium presentation rate (910 msec ISI), N1 and P2 latencies were prolonged for older listeners in response to the speech stimulus but not the tone stimulus. These age effects were absent when stimuli were presented at a slower rate (1510 msec ISI). Results from this study suggest that rapidly occurring stimulus onsets, either within a stimulus or between stimuli, result in prolonged N1 and P2 responses in older adults. This is especially true when processing complex stimuli such as speech. One potential explanation for this age effect might be age-related refractory differences in younger and older auditory systems. Refractory issues might in turn affect synchronized neural activity underlying the perception of critical time-varying speech cues and may partially explain some of the difficulties older people experience understanding speech.     

事件相关电位在听觉训练中的应用

听觉主要是指人体有意识地接受言语声音刺激信号．对接收到的信息进行一系列的分析、统合、定位、理解的过程。听力是指个体对声音的感知能力,是先天性的．主要依靠于机体的听觉感知器官。听力与听觉密不可分,没有听力就不可能有听觉能力,听力越好,获得的声刺激信号越多．听觉能力发展越快。     

The effects of speech presentation level on acceptance of noise in listeners with normal and impaired hearing.

PURPOSE: To compare the effects of speech presentation level on acceptance of noise in listeners with normal and impaired hearing. METHOD: Participants were listeners with normal (n = 24) and impaired (n = 46) hearing who were matched for conventional acceptable noise level (ANL). ANL was then measured at 8 fixed speech presentation levels (40, 45, 50, 55, 60, 65, 70, and 75 dB HL) to determine if global ANL (i.e., ANL averaged across speech presentation levels) or ANL growth (i.e., the slope of the ANL function) varied between groups. RESULTS: The effects of speech presentation level on acceptance of noise were evaluated using global ANLs and ANL growth. Results showed global ANL and ANL growth were not significantly different for listeners with normal and impaired hearing, and neither ANL measure was related to pure-tone average for listeners with impaired hearing. Additionally, conventional ANLs were significantly correlated with both global ANLs and ANL growth for all listeners. CONCLUSION: These results indicate that the effects of speech presentation level on acceptance of noise are not related to hearing sensitivity. These results further indicate that a listener's conventional ANL was related to his or her global ANL and ANL growth.     

Tone burst stimulus for auditory brainstem responses: Prediction of hearing threshold at 1 kHz

Objective

To assess differences in hearing threshold estimation of four different ABR tone-bursts at 1 kHz.

Methods

Twenty-one (21) ears from 11 subjects were tested with pure-tone audiometry (PTA): 5 ears (24%) were normal hearing, 5 (24%) affected by mild hearing loss, 7 (33%) showed moderate hearing loss and 4 (19%) severe hearing loss. After PTA each subject underwent tone-burst ABR test at 1 kHz using a linear gated (L_ABR) or Blackman windowed (B_ABR) stimuli with (nn_ABR) and without ipsilateral notched noise. Stimulation rate and filters settings were unchanged.

Results

Overall correlation between PTA and all ABRs thresholds was high, ranging from 0.84 to 0.94. In normal hearing ears none of the differences was significant, except for those measured with B_nn_ABR, which showed a mean 16 dB overestimation of the pure-tone threshold (p < 0.05). In mild hearing loss group none of the differences between thresholds were significant. In moderate and severe hearing loss groups significant differences were measured with L_nn_ABR (p < 0.05) with a mean 7.5 dB underestimation of PTA.

Conclusions

Although very similar, some significant differences were found when considering specific group of patients with different degrees of hearing loss.     

流行病学调查中0.5 kHz听阈值对听力分级的影响

目的探讨流行病学调查中0.5kHz听阈校正值对听力分级的影响。方法在本底噪声45dB(A)条件下,测试6626人纯音气导听力,将0.5kHz听阈减去15dB修正值,比较修正后的0.5kHz、1kHz、2kHz、4kHz平均听阈与1kHz、2kHz、4kHz平均听阈对听力分级的影响。结果修正后的4个频率平均值计算的听力减退率和听力残疾率与3个频率平均值计算的结果无统计学差异。结论在流行病学调查中测听环境达不到标准隔音时,采用修正值是可行的,其4个频率计算听力分级更符合WHO标准。     

Effects of stimulus level on cortical auditory event-related potentials evoked by speech

The effect of stimulus level on cortical auditory event-related potentials (ERPs) evoked by consonant-vowel (CV) contrasts, /ta/, /da/, and /sa/, was investigated. The lowest level at which CVs were discriminated with >95% accuracy was determined for 15 normally hearing adults. ERPs were obtained at 0, 20, and 40 dB SL above this level during active listening. ERP latencies decreased as level increased. P300 amplitude did not vary with CV level or type; however, obligatory ERPs decreased in amplitude as level increased. The effect of level on P300 latency is likely related to the cognitive processing speed needed to perform speech discrimination. Obligatory ERP amplitude results suggest that attention demands vary with level during discrimination of speech features.     

Visual attention in deaf and normal hearing adults: effects of stimulus compatibility.

Visual perceptual skills of deaf and normal hearing adults were measured using the Eriksen flanker task. Participants were seated in front of a computer screen while a series of target letters flanked by similar or dissimilar letters was flashed in front of them. Participants were instructed to press one button when they saw an H, and another button when they saw an N. Targets H and N were flashed with flanking letters that were either H or N, creating response-compatible and response-incompatible arrays. Flankers were presented at different distances from the targets and reaction times were measured. In the present study, reaction times were significantly faster for the hearing group than for the deaf group. However, the hearing group had significantly more errors on this task than the deaf group, suggesting that the deaf participants may have been more deliberate in their responses. In addition, the deaf group revealed a significantly greater interference effect than the hearing group at a parafoveal (i.e., 1.0 degrees ) eccentricity. These findings suggest that deaf individuals may allocate their visual resources over a wider range than those with normal hearing.     

The effects of click and tone-burst stimulus parameters on the vestibular evoked myogenic potential (VEMP)

Vestibular evoked myogenic potentials (VEMP) are short latency electromyograms (EMG) evoked by high-level acoustic stimuli and recorded from surface electrodes over the tonically contracted sternocleidomastoid (SCM) muscle and are presumed to originate in the saccule. The present experiments examined the effects of click and tone-burst level and stimulus frequency on the latency, amplitude, and threshold of the VEMP in subjects with normal hearing sensitivity and no history of vestibular disease. VEMPs were recorded in all subjects using 100 dB nHL click stimuli. Most subjects had VEMPs present at 500, 750, and 1000 Hz, and few subjects had VEMPs present at 2000 Hz. The response amplitude of the VEMP increased with click and tone-burst level, whereas VEMP latency was not influenced by the stimulus level. The largest tone-burst-evoked VEMPs and lowest thresholds were obtained at 500 and 750 Hz. VEMP latency was independent of stimulus frequency when tone-burst duration was held constant.     

健听人在不同本底噪声环境中的听阈值分析

目的计算健听人在不同本底噪声环境中的听阈值,通过与在标准测听环境中的结果相比较,确定非标准测听环境中听阈的修正值,探讨听力残疾抽样调查中最低环境本底噪声级的控制值。方法在不同的本底噪声环境中,采用纯音测试和声场测试的方法,对50人(100耳)分别进行测听。结果研究结果显示,在本底噪声分别为45dB(A)、50dB(A)、55dB(A)的测听环境中,健听者的纯音测试听阈值分别为15dBHL、20dBHL、25dBHL,与标准测听环境中的听阈差值分别为10dBHL、15dBHL、20dBHL;声场测试听阈值分别为25dBHL、30dBHL、35dBHL,与标准测听环境中的听阈差值分别为15dBHL、20dBHL、25dBHL;统计结果显示,不同本底噪声环境中,健听人的听阈值具有显著性差异。结论根据健听人在不同本底噪声环境中与在标准测听环境中的听阈差值,可以确定在非标准测听室及相应本底噪声环境中的听阈修正值,也可以确定听力残疾评定允许测听环境最高噪声级。     

流行性腮腺炎病毒感染对听力影响的研究

目的探讨流行性腮腺炎病毒感染临床类型对患儿听力的影响及其特征。方法:将2005年7月我院收治的28名流行性腮腺炎患儿分为两组,一组为流行性腮腺炎合并脑膜脑炎(22人),另一组为无神经系统并发症的腮腺炎患儿(6人),均进行了耳部体检及畸变产物耳声发射(Distortionproductsofotoacousticemissions,DPOAE)、听性脑干反应(Auditory-evokedbrainstemresponses,ABR)的检查,并与10名正常同龄儿童的检查结果相比较。结果1.所有流行性腮腺炎患儿发病期间ABR阈值均正常。2.两组流行性腮腺炎病毒感染患儿DPOAE通过率均为75.0%,6000Hz、8000Hz反应幅值有统计学差异(p<0.05)。3.三组受试者ABR检查中,Ⅰ波、Ⅴ波潜伏期及Ⅰ～Ⅴ波间期均值有统计学差异(F=4.61,4.64,3.73,p<0.05).而Ⅲ波、Ⅰ～Ⅲ波间期、Ⅲ～Ⅴ波间期无明显统计学差异(p>0.05)。结论:1.所有流行性腮腺炎病毒感染患儿患病期间听力均正常。2.流行性腮腺炎病毒感染可影响患儿的耳蜗、听神经及脑干某些听觉核团的功能,而且合并脑膜脑炎较单纯腮腺感染的影响更显著,发生听损伤的危险性更大。     

纯音和言语刺激声强度对听觉事件相关电位的影响

目的:探讨分别以纯音和言语作刺激声时声强度对听觉事件相关电位(AERP)的影响.方法:采用不同强度的纯音和言语作为刺激声对正常年青人进行AERP测试,比较纯音和言语诱出典型P300的强度范围,分析不同强度对P300的影响是否同时存在于纯音和言语刺激声.结果:言语刺激声比纯音更容易在40～70 dBSL范围内连续记录到典型波形,差异有统计学意义(P＜0.01).言语或纯音刺激时,强度对P300潜伏期的影响差异均有统计学意义(P＜0.01),在40～70 dBSL范围内潜伏期随强度增加而减小,强度对P300幅值的影响差异均无统计学意义.结论:强度对AERP的影响在纯音和言语刺激时基本相同,但言语得到典型AERP波形的强度范围较纯音宽,其原因可能与言语刺激声包含的信息较纯音刺激声丰富,受试者对汉语言语刺激声较纯音更熟悉有关.