Department of Experimental Audiology, Otto von Guericke University Magdeburg, Magdeburg, Germany.
Physikalisch-Technische Bundesanstalt, Braunschweig, Germany.
PLoS One. 2023 Jul 31;18(7):e0289216. doi: 10.1371/journal.pone.0289216. eCollection 2023.
Infrasounds are signals with frequencies below the classical audio-frequency range, i.e., below 20 Hz. Several previous studies have shown that infrasound is audible as well, provided that the sound level is high enough. Hence, the sound pressure levels at threshold are much higher than those in the classical audio-frequency range. The present study investigates how the duration and the shape of the temporal envelope affect thresholds of infrasound stimuli in quiet. Two envelope types were considered: one where the duration of the steady state was varied (plateau bursts) and one where the number of consecutive onset-offset bursts was varied (multiple bursts). Stimuli were presented monaurally to human listeners by means of a low-distortion sound reproduction system. For both envelope types, thresholds decrease with increasing duration, a phenomenon often referred to as temporal integration. At the same duration, thresholds for plateau-burst stimuli are typically lower than those for multiple-burst stimuli. The data are well described by a slightly modified version of a model that was previously developed to account for temporal integration in the classical audio-frequency range. The results suggest similar mechanisms underlying the detection of stimuli with frequencies in the infrasound and in the classical audio-frequency range. Since the model accounts for the effect of duration and, more generally, the shape of the envelope, it can be used to enhance the comparability of existing and future datasets of thresholds for infrasounds with different temporal stimulus parameters.
次声是频率低于经典音频范围（即低于 20 Hz）的信号。几项先前的研究表明，只要声级足够高，次声也是可听的。因此，次声刺激的阈值处的声压级远高于经典音频范围内的声压级。本研究探讨了在安静环境中，时间包络的持续时间和形状如何影响次声刺激的阈值。考虑了两种包络类型：一种是稳态持续时间变化的（平板爆发），另一种是连续起始-结束爆发次数变化的（多次爆发）。通过低失真声音再现系统，将刺激单耳呈现给人类听众。对于这两种包络类型，阈值随持续时间的增加而降低，这种现象通常称为时间整合。在相同的持续时间内，平板爆发刺激的阈值通常低于多次爆发刺激的阈值。数据可以很好地用之前为经典音频范围内的时间整合而开发的模型的略微修改版本来描述。结果表明，在检测次声和经典音频范围内频率的刺激时，存在类似的机制。由于该模型考虑了持续时间的影响，更一般地说，考虑了包络的形状，因此它可以用于增强具有不同时间刺激参数的次声阈值的现有和未来数据集的可比性。
