Department of Biomedical Engineering, Neurosensory Laboratory, University of Miami, Coral Gables, Florida, USA.
Ear Hear. 2012 Sep-Oct;33(5):660-71. doi: 10.1097/AUD.0b013e31824d8f18.
Both 80 Hz auditory steady state responses (ASSRs) and tone burst auditory brainstem responses (ABRs) have been shown to provide reasonable estimates of the behavioral thresholds. Although ASSRs provide statistically objective estimates that can be easily automated by computers, they present no information for the neurophysiological interpretation of the results. ABRs, on the other hand, do not provide easily automated information and usually need expert interpretation of the recorded waveforms. A recently developed continuous loop averaging deconvolution algorithm offers an alternative solution by acquiring slightly jittered 80 Hz quasi auditory steady state responses (QASSRs), thus enabling the acquisition of both recordings simultaneously. The purpose of this study is to investigate a specially developed 80 Hz QASSR paradigm for simultaneous acquisition for both responses for threshold detection purposes.
Sixteen ears from eight adults with normal hearing were tested. Amplitude modulated QASSRs were obtained using slightly jittered temporal sequences of tone bursts presented at a mean rate of 78.125 Hz. Four carrier frequencies (500, 1000, 2000, and 4000 Hz) at several stimulus intensity levels were monaurally presented and QASSRs to 128 sweeps blocks were recorded. The ABRs were extracted using the CLAD algorithm. Wave V was visually identified and analyzed in the time domain as in everyday clinical practice. In addition, statistically objective ƒMP computation method was used to automatically detect ABR threshold as well. The QASSRs were analyzed in the frequency domain and magnitudes, phase delays, and thresholds were obtained. Phasor (polar plot) diagrams were constructed. QASSR and ABR hearing thresholds were obtained and compared with behavioral thresholds.
Study reveals that the QASSR method provides accurate objective estimation of the audiometric thresholds from extracted ASSRs and latency/amplitude information from extracted ABRs. The largest mean threshold difference for QASSR was within 5 dB for all carrier frequencies including 500 Hz. For auditory threshold estimation in adults with normal hearing, the Hotelling's T-Square test in four dimensions in the frequency domain was more accurate than the ƒMP or visual ABR threshold detection in the time domain.
Simultaneously recorded ASSR and ABR from QASSRs provide accurate and effective method for frequency-specific hearing threshold estimation with neurophysiological information in adults with normal hearing. Further research is required for hearing-impaired adults, newborns, and infants.
80Hz 听觉稳态响应（ASSR）和短声听觉脑干反应（ABR）均已被证明可提供行为阈值的合理估计。虽然 ASSR 提供了可通过计算机轻松自动统计的客观估计，但它们没有提供结果神经生理学解释的信息。ABR 则无法提供易于自动处理的信息，通常需要专家对记录的波形进行解释。最近开发的连续循环平均去卷积算法提供了一种替代解决方案，即获取略有抖动的 80Hz 准听觉稳态响应（QASSR），从而能够同时获取两种记录。本研究的目的是研究一种专门开发的 80Hz QASSR 范式，用于同时获取两种反应以进行阈值检测。
对 8 名听力正常的成年人的 16 只耳朵进行了测试。使用在平均率为 78.125Hz 的短暂声脉冲的略有抖动的时序列获取调幅 QASSR。以单耳方式呈现 4 个载波频率（500、1000、2000 和 4000Hz）和多个刺激强度级别的 QASSR，并记录 128 个扫频块。使用 CLAD 算法提取 ABR。在时域中，如在日常临床实践中一样，对波 V 进行视觉识别和分析。此外，还使用了统计客观 ƒMP 计算方法来自动检测 ABR 阈值。在频域中分析 QASSR，并获得幅度、相位延迟和阈值。构建了相量（极坐标）图。获得了 QASSR 和 ABR 听力阈值，并与行为阈值进行了比较。
研究表明，QASSR 方法可从提取的 ASSR 中提供准确的客观估计，并从提取的 ABR 中提供潜伏期/幅度信息，从而准确估计听力阈值。对于所有载波频率，包括 500Hz，QASSR 的最大平均阈值差异在 5dB 以内。对于听力正常的成年人的听觉阈值估计，在频率域中进行的 Hotelling 的 T-平方检验在四个维度比时域中的 ƒMP 或视觉 ABR 阈值检测更准确。
从 QASSR 同时记录的 ASSR 和 ABR 提供了一种准确有效的方法，可在听力正常的成年人中进行特定频率的听力阈值估计，并提供神经生理学信息。需要进一步研究听力受损成年人、新生儿和婴儿。
