【英语时差8，16】男孩变声时

 For adolescent boys, a changing voice that cracks in the middle of a sentence can be a great embarrass-ment. Though embarrassing, a cracking voice is a natural part of adolescent development. As a boy goes through adolescence¹, his secondary sex characteristics develop. One of these characteristics is the rapid growth of the larynx and vocal² cords. A boy's voice deepens as his larynx develops because the bigger the vocal cords, the deeper the voice.

In fact, vocal cords are similar to other musical instruments in this regard. The longer the harp³ string, for instance, the lower the note it plays. Similarly, if you are blowing into a bottle to create a certain pitch, the larger the bottle, the lower the pitch. When it comes to voices, the bigger the vocal cords, the lower they resonate, and the deeper the voice will be.

But why does a boy's changing voice break and crack? For the same reason growing adolescents are often gangly and awkward. Because the brain is becoming accustomed to working with bigger body parts. Even for an adult, a consistent and even voice depends on the brain's ability to constantly monitor the sounds that come from the voice. The brain can do this quite easily under normal circumstances. But, when a boy's vocal cords enlarge, the brain must relearn how to monitor and control the voice. A cracking voice is proof that an adolescent boy's brain hasn't become completely proficient⁴ at coordinating⁵ its careful monitoring of the sounds coming from the vocal cords.

1 adolescence   

n.青春期，青少年

参考例句：

• Adolescence is the process of going from childhood to maturity.青春期是从少年到成年的过渡期。
• The film is about the trials and tribulations of adolescence.这部电影讲述了青春期的麻烦和苦恼。

2 vocal   

adj.直言不讳的；嗓音的；n.[pl.]声乐节目

参考例句：

• The tongue is a vocal organ.舌头是一个发音器官。
• Public opinion at last became vocal.终于舆论哗然。

3 harp   

n.竖琴；天琴座

参考例句：

• She swept her fingers over the strings of the harp.她用手指划过竖琴的琴弦。
• He played an Irish melody on the harp.他用竖琴演奏了一首爱尔兰曲调。

4 proficient   

adj.熟练的，精通的；n.能手，专家

参考例句：

• She is proficient at swimming.她精通游泳。
• I think I'm quite proficient in both written and spoken English.我认为我在英语读写方面相当熟练。

5 coordinating   

v.使协调，使调和( coordinate的现在分词 )；协调；协同；成为同等

参考例句：

• He abolished the Operations Coordinating Board and the Planning Board. 他废除了行动协调委员会和计划委员会。 来自辞典例句
• He's coordinating the wedding, and then we're not going to invite him? 他是来协调婚礼的，难道我们不去请他？ 来自电影对白