Data for: Visualization of acoustic waves in air and subsequent audio recovery with a high-speed schlieren imaging system (Harvey et al.)

This depository contains video files obtained from high-speed schlieren imaging of acoustic waves propagating through air, produced by a speaker. For each video (.avi format), the start of the name corresponds to the frequency of the wave (if a sine wave) or the frequency of its fundamental harmonic (if a square wave). This ranges from 110 Hz to 40 kHz. The next part of the filename corresponds to the type of waveform sent from the function generator to drive the speaker, either a square wave ('sq1') or a sine wave ('sine1'); it should be noted that the actual audio output was limited by the frequency response of the speaker (which falls off sharply around 40 kHz), so a 'square' wave at 20 kHz will in practice be very similar to a sine wave. The last part of the filename describes the parameter changed for each trial. For the majority of videos, this describes the SPL of the speaker output, which falls in the range of 75 dB (for a 40 kHz sine wave) to 120 dB (for frequencies between 220 Hz and 15 kHz). For other videos, this describes a parameter of imaging: either frame rate (in frames per second x1000, 'kfps'), exposure (microseconds, 'us'). Files ending with '31kfps' have been imaged using a different camera position, to optimise the spatial resolution of the image. Each .avi video file is accompanied by a .cih file similarly named; this contains metadata from the high-speed camera. When read as a text file, imaging parameters can be inspected.本数据集存储库收录了由扬声器产生、在空气中传播的声波的高速纹影成像（high-speed schlieren imaging）视频文件。对于每个.avi格式视频文件，其文件名的起始部分对应声波的频率：若为正弦波，则对应其自身频率；若为方波，则对应其基频，整体频率覆盖范围为110 Hz至40 kHz。文件名的中间段对应函数发生器驱动扬声器时所发送的波形类型，可选方波（'sq1'）或正弦波（'sine1'）。需注意，实际音频输出受扬声器的频率响应限制（在约40 kHz处急剧衰减），因此20 kHz的方波在实际表现上会与正弦波极为相似。文件名的最后一部分，描述了单次试验中调整的参数。对于绝大多数视频文件，该参数为扬声器输出的声压级（sound pressure level, SPL），其范围为75 dB（对应40 kHz正弦波）至120 dB（对应220 Hz至15 kHz之间的频率）。对于其余视频文件，该参数为成像相关参数：包括帧率（以千帧每秒为单位，'kfps'）或曝光时长（以微秒为单位，'us'）。文件名以'31kfps'结尾的视频，采用了不同的相机拍摄位置，以优化图像的空间分辨率。每个.avi格式视频文件均附带一个同名的.cih文件，该文件包含高速相机的元数据。将其作为文本文件读取时，可查看所有成像相关参数。