Video Text:

[θ] and [ð] are paired together because they take the same mouth position. Th is unvoiced, you make the sound with just air, and dth voiced, you use the vocal cords to produce the sound. The mouth position. As you can see, the tongue comes through the teeth, but it is only the tip of the tongue. Sometimes when people are learning, they use too much of their tongue, dth. That will make it very difficult to speak. Also, a common mistake is to not put the tongue through the teeth at all, and make a dd sound. Dd. That is also not correct. Make sure just the tip of the tongue comes through your teeth: th. Sample word pairs: because I think it is especially helpful for these sounds, I'm going to go through them once slow and once normal.[θ]和[ð]有着相似的发音动作，所以我也把它们放在一起讲。Th，是清辅音，也就是用气流发声（而不振动声带），而dth是浊辅音，我们就要用声带振动发声。下面讲讲口腔发音位置。你可以观察到，但是它只用到舌尖。有人在学习这个音标发音时，舌头伸得过长，dth。那样就会使得发音困难了。还有一个容易错的地方呢，是不把舌头伸出牙齿，结果发出了dd的音。Dd。这就是不正确的发音方式。要注意只把舌尖伸出牙齿：th。单词举例：我会先慢速念一遍，再用正常语速念一遍，因为我觉得这样示范对这些音的发音特别有帮助。

Word pairs:

thin 瘦的—this这个

thief 小偷—these这些

birthday 生日—worthy 值得的