Measurement of sound field and intelligibility of speech in snow

在本研究项目中，测量了两种不同积雪的隔声声学特性：(1)天然积雪；(2)踩踏压缩积雪。还测量了被压缩的雪堆在表面上踩踏和贴着滑雪杆直接振动的声学特性。在自然积雪的情况下，高频范围的相对功率比低频范围的相对功率衰减得更多，而在压缩积雪的情况下，相对功率在较宽的频率范围内均匀衰减。在压缩雪中，衰减在所有频域均匀地达到40分贝以上。另一方面，在直接振动积雪的方法中，如滑雪杆粘贴和踩踏，在30厘米深处测得的声压级在宽频域内比MAF(最小可听场)高约20dB。此外，即使振动点在水平方向上距离麦克风位置1米远，60厘米处的声压级也比1000赫兹时的最大声压级高10分贝。结果表明，坚持用滑雪杆在葬礼上发出声音是有效的，而且比语音呼叫要好得多。

In this research project, acoustic characteristic of sound insulation of two different snow packs: (1) a natural snow pack; and (2) a compressed snow pack by stomping, were measured. Acoustic characteristics of a compressed snow pack directly vibrated by stomping on surface and sticking with ski poles were also measured. In the case of a natural snow pack, the relative power of a high-frequency range was attenuated more than that of a lower-frequency range, and in the case of a compressed snow pack, the relative power was uniformly attenuated across a wide frequency range. In a compressed snow, attenuation reached to more than 40 dB uniformly in all frequency domains. On the other hands, in a method directly vibrating a snow pack, such as ski-pole sticking and stomping, sound pressure level measured at 30 cm depth was about 20 dB greater than the MAF (minimum audible field) across a wide frequency domain. Furthermore, even if a vibrating point was 1 m far from the position of a microphone in a horizontal direction, sound pressure level at 60 cm was 10 dB greater than the MAF at 1000Hz. The results suggest that sticking with ski poles is effective to send sounds to a burial, and much better than voice call.