Rapid-FFR: Developing a rapid method of measuring the auditory frequency following response for use in children and infants

在听力学临床中最常用的电生理测量是点击诱发的听觉脑干反应（ABR）。广泛用于新生儿听力筛查项目，其优点是只需2-3分钟即可测量（一旦放置电极），这是测试婴儿和儿童时的重要考虑因素。虽然有很大的用途，但人们可以在短时间内从这样一个简单的刺激中获得的信息是有限的，并且点击诱发的ABR主要用于检测听力损失。最近，人们越来越关注另一种听觉反应，即所谓的频率跟随反应（FFR）。血流储备分数是一种头皮记录的电生理测量，反映了响应于沿着听觉通路的周期性听觉刺激的持续同步神经放电。最近的证据表明，通过改变刺激的基频（F0），有可能有利于听觉通路不同层次的神经发生器，相对较低的频率F0导致更多的皮层贡献，较高的频率加权较低水平的脑干贡献。此外，通过这种技术，唤起声音在声学上比点击声复杂得多，甚至包括语音。由于可以探索的声学属性的种类更广泛，因此可以比相对粗糙的点击ABR更具体地针对各种语音相关特征。最重要的是，人类和动物研究都表明，FFR和ABR测量神经生理功能的互补方面，与行为不同，以及反映不同的神经群体。简而言之，血流储备分数是一个有用的工具，可以用于婴儿和儿童的听觉诊断，并可能允许探测听觉通路的不同阶段。测量血流储备分数的一个重要方面，阻碍了他们在临床上的采用是测量它们所花费的时间。FFR通常被记录为离散的静音分离刺激，持续时间为40 - 150 ms，有时高达2 s。收集稳健的FFR可能需要长达30分钟，因为它需要大约2000-3000次刺激重复，并且通常认为期望记录信号的正极性和负极性。这些措施对成年参与者来说已经够麻烦的了。对于婴儿和儿童来说，血流储备分数所需的时间对其更广泛的使用构成了重要障碍。我们一直在开发一种测量血流储备分数的新方法，其中刺激连续呈现（即，没有刺激间间隔）并在响应的单个周期上求平均。对于我们使用的特定刺激，FFR记录时间从标准技术的约2.5分钟减少到使用我们的新技术（Rapid-FFR）的仅35秒，数据质量相当。这种采集时间的减少意味着在一个会话中测试大量条件以及测试难以长时间保持静止的参与者变得更容易。在这个项目中，我们建议更充分地调查使用这种技术在成年人中，不同的，例如，F0的刺激，以及目前的声学特征，特别强调在语音感知的关键功能。其次，我们计划将其应用于儿童和婴儿，以期使该技术可行，用于将FFR测量纳入听力学测试组合。

The most commonly used electrophysiological measure in the audiological clinic is that of the click-evoked Auditory Brainstem Response (ABR). Used widely in newborn hearing screening programmes, it has the advantage of taking only 2-3 minutes to measure (once the electrodes are placed), an important consideration when testing infants and children. Although of great utility, the information one can gain in a short time from such a simple stimulus is limited, and click-evoked ABRs have mostly been used to detect hearing loss.Recently, there been a growing interest in another auditory response, the so-called frequency following response (FFR). The FFR is a scalp-recorded electrophysiological measure which reflects sustained synchronous neural firing in response to periodic auditory stimuli along the auditory pathway. Recent evidence suggests that by varying the fundamental frequency (F0) of the stimuli, it is possible to favour neural generators at different levels of the auditory pathway, with relatively low frequency F0s leading to more cortical contributions, and higher frequency ones weighting lower level brainstem contributions. Also, with such a technique, evoking sounds can be much more acoustically complex than clicks, even including speech sounds. Because of the wider variety of acoustic attributes that can be explored, it is possible to target various speech-related features more specifically than is possible with a relatively crude click ABR. Most importantly, both human and animal studies show that the FFR and ABR measure complementary aspects of neurophysiological functioning, relating to behaviour differently, as well as in reflecting different neural populations. In short, FFRs could be a useful tool to use in auditory diagnoses in infants and children, and might allow the probing of different stages in the auditory pathway.One important aspect of measuring FFRs that impedes their adoption in the clinic is the time it takes to measure them. FFRs are typically recorded to discrete silence-separated stimuli with a duration of 40 - 150 ms and sometimes up to as much as 2 s. Collecting a robust FFR can take up to 30 minutes as it requires approximately 2000-3000 repetitions of the stimulus, and it is often considered desirable to record both positive and negative polarities of the signal. Such measures are onerous enough in adult participants. For infants and children, the time required for FFRs poses an important obstacle to their more general use.We have been developing a new method for measuring FFRs, in which the stimulus is presented continuously (i.e., without an interstimulus interval) and averaging across a single cycle of the response. For the particular stimulus we used, FFR recording times were reduced from approximately 2.5 minutes for the standard technique to only 35 seconds using our new one (Rapid-FFR), with comparable data quality. This reduction in acquisition time means that that it becomes easier to test a larger number of conditions within one session and to test participants who have difficulty remaining still for a long time. In this project, we propose to investigate more fully the use of this technique in adults, varying, for example, the F0 of the stimuli, as well as the acoustic features present, with a particular emphasis on features crucial in speech perception. Secondly, we plan to apply it in children and infants, with a view towards making the technique viable for measurements of the FFR to be included in audiological test batteries.