A mobile phone vibrating on a hard surface often sounds qualitatively unlike ordinary audiovisual recordings when reproduced through laptop loudspeakers. We propose that part of this perceptual distinctiveness can be described as a nested periodicity: a first-order cepstral structure reflecting the vibration period and its multiples, and a second-order cepstral structure reflecting repeated spacing within the first-order cepstrum. Treating the perceptual effect as real and using a deliberately transparent synthetic signal chain, we model six stages: mechanical generation, surface and air propagation, microphone capture, encoding and decoding, laptop-speaker playback, and re-recording or post-processing. The synthetic analysis shows that the first-order cepstral periodicity is preserved across the chain, whereas a cleaner bimodal or quasi-bimodal second-order cepstral signature is most evident at the mechanical source and at laptop-speaker playback. The result supports, but does not prove, the hypothesis that laptop reproduction can re-emphasize a latent contact-vibration periodicity that is less cleanly expressed in intermediate recorded and encoded forms. We frame second-order cepstral bimodality as an exploratory descriptor of contact-vibration playback rather than as a completed perceptual metric. Required validation includes recordings of real devices, controlled playback transfer functions, perceptual judgments, and comparisons against ordinary speech, music, and environmental recordings.

翻译：手机在硬表面上振动时，经由笔记本电脑扬声器再现，其声音往往在本质上不同于常规视听记录。我们提出，这种感知独特性的部分可以描述为一种嵌套周期性：一阶倒谱结构反映振动周期及其倍数，二阶倒谱结构反映一阶倒谱中重复的间距。我们将感知效应视为真实存在，并采用精心设计的透明合成信号链，模拟六个阶段：机械生成、表面与空气传播、麦克风捕获、编码与解码、笔记本电脑扬声器播放，以及重新录制或后处理。合成分析显示，一阶倒谱周期性在整个链中得到保留，而更清晰的二阶倒谱双峰或近似双峰特征在机械源和笔记本电脑扬声器播放阶段最为明显。该结果支持（但未证明）以下假设：笔记本电脑重现会重新强调一种潜在的接触振动周期性，而这种周期性在中间记录和编码形式中未得到清晰表达。我们将二阶倒谱双峰性视为接触振动播放的探索性描述符，而非一个完备的感知度量。必要的验证包括真实设备的记录、受控的播放传递函数、感知判断，以及与常规语音、音乐和环境记录的对比。