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. 没有人确切知道为何家猫会发出呼噜声，但很多人都把这种声音理解成是一种心满意足的表现。我们人类对于家猫为何发呼噜声的认识正日趋完善；大多数科学家都赞成该现象与喉、喉部肌肉和神经元振荡器有关。

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. 幼猫在几天大的时候就学会发出呼噜声了。兽医们认为这是在告诉猫妈妈“我挺好的”和“我在这儿呢”之类的信息。发呼噜声也说明幼猫和猫妈妈之间存在着一种亲密的心理感应关系。

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. 幼猫成长为成年猫的过程中，会继续发出呼噜声。很多人都认为猫是因为满足和愉快才发出这种声音的。但是，猫受了伤或处于疼痛中时，也会发出呼噜声。著名的生物生学家伊丽莎白•冯•穆根塔勒提出，呼噜声连同其低频振动是一种“天然的治疗机制”。发出呼噜声或许与骨骼的加固与矫正，减轻疼痛以及愈合伤口有着某种联系。

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. 呼噜声是家猫所特有的发音特征。然而，在猫科动物中，其他种类也会发出呼噜声，如短尾猫、猎豹、欧亚猞猁、美洲狮和野猫。尽管像狮子一类的大型猫科动物也会发出呼噜般的声音，研究却表明豹亚科动物，比如狮子、老虎、美洲豹、美洲虎、雪豹及云豹，并不能发出真正的呼噜声。

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. 呼噜声与猫科动物的其他发声的不同之处在于，前者产生于整个呼吸循环（包括吸气和呼气）过程中；而像“喵”这样的其他发声现象仅在呼气的时候产生。

（英语点津Jennifer编辑）

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