No one knows for sure why a domestic cat purrs, but many people interpret the sound as one of contentment. Our understanding of why a domestic cat purrs is becoming more complete; most scientists agree that the larynx (voice box), laryngeal muscles, and a neural oscillator are involved. 沒有人確切知道為何家貓會發出呼嚕聲，但很多人都把這種聲音理解成是一種心滿意足的表現。我們人類對于家貓為何發呼嚕聲的認識正日趨完善；大多數科學家都贊成該現象與喉、喉部肌肉和神經元振蕩器有關。

Kittens learn how to purr when they are a couple of days old. Vets suggest that this purring tells "Mom" that "I am okay" and that "I am here". It also indicates a bonding mechanism between kitten and mother. 幼貓在幾天大的時候就學會發出呼嚕聲了。獸醫們認為這是在告訴貓媽媽“我挺好的”和“我在這兒呢”之類的信息。發呼嚕聲也說明幼貓和貓媽媽之間存在著一種親密的心理感應關系。

As the kitten grows into adulthood, purring continues. Many suggest a cat purrs from contentment and pleasure. But a cat also purrs when it is injured and in pain. Dr. Elizabeth Von Muggenthaler, a famous bioacoustician, has suggested that the purr, with its low frequency vibrations, is a "natural healing mechanism". Purring may be linked to the strengthening and repairing of bones, relief of pain, and wound healing. 幼貓成長為成年貓的過程中，會繼續發出呼嚕聲。很多人都認為貓是因為滿足和愉快才發出這種聲音的。但是，貓受了傷或處于疼痛中時，也會發出呼嚕聲。著名的生物生學家伊麗莎白?馮?穆根塔勒提出，呼嚕聲連同其低頻振動是一種“天然的治療機制”。發出呼嚕聲或許與骨骼的加固與矯正，減輕疼痛以及愈合傷口有著某種聯系。

Purring is a unique vocal feature in the domestic cat. However, other species in the Felidae family also purr: bobcat, cheetah, Eurasian lynx, puma, and wild cat. Although some big cats like lions exhibit a purr-like sound, studies show that the Patherinae subfamily: lion, tiger, leopard, jaguar, snow leopard, and clouded leopard do not exhibit true purring. 呼嚕聲是家貓所特有的發音特征。然而，在貓科動物中，其他種類也會發出呼嚕聲，如短尾貓、獵豹、歐亞猞猁、美洲獅和野貓。盡管像獅子一類的大型貓科動物也會發出呼嚕般的聲音，研究卻表明豹亞科動物，比如獅子、老虎、美洲豹、美洲虎、雪豹及云豹，并不能發出真正的呼嚕聲。

What makes the purr distinctive from other cat vocalizations is that it is produced during the entire respiratory cycle (inhaling and exhaling). Other vocalizations such as the "meow" are limited to the expiration of the breath. 呼嚕聲與貓科動物的其他發聲的不同之處在于，前者產生于整個呼吸循環（包括吸氣和呼氣）過程中；而像“喵”這樣的其他發聲現象僅在呼氣的時候產生。

（英語點津Jennifer編輯）

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