voices 不到的声音.PDF

千奇百趣大自然 Amazing Nature 不到的聲音 voices 文 | 吳卓希 Text | Hayward Ng 「有風，花在動，無風，花也潮水一般地動……這一切交織在一起，再加上風聲， 天籟人籟，就如同海上午夜的潮聲。」這是近代詩人李廣田所寫的《花潮》，描寫 了大自然與人們的聲音，兩者交織出的和諧與共融。風聲潮聲我們當然聽得到，然 而，大自然當中隱藏著更多的是我們「聽不到」的聲音。各式各樣的生物，每天在 人類音頻接收範圍以外，「無聲地」溝通著。 Modern Chinese poet Li Guangtian once described the peaceful mingling of natural sounds and human voices in his poem “Hua Chao” (Flower Tide). Of course, we can hear the sound of wind and waves, but there are many unheard voices hiding in the natural world. Many living things communicate using sounds that are beyond the range of human hearing. 海豚 Dolphins The frequency range of sounds 海豚所發出的音頻範圍比人類闊得多，人 emitted by dolphins is much 們可接收的音頻範圍一般在20 – 20,000Hz wider than for humans. Typically, humans can hear sounds with （赫茲），一些海豚物種就能夠發出高達 frequencies from 20 – 20,000Hz 150,000Hz的聲音。除了與同伴溝通，海豚更 (Hertz). Some dolphin species can 會以聲音來「看」東西，牠們會發出超聲波 emit sounds with frequencies as high as （高於 的聲音），用以確定自己的 150,000Hz. In addition to communicating 20,000Hz 位置和避開障礙物。這種以聲音來導航的方 with their peers, dolphins also use sound to “see”. They emit ultrasound (sound with location and shape of nearby objects 式，稱為「回聲定位」。原理是透過接收各 frequencies above 20,000Hz) to detect by receiving reflected sound waves. 種物件反射自己所發出的聲波，從而判斷出 one another and avoid obstacles. This Dolphins also rely on “echolocation” for 周邊物件的距離、