Fricative are often a source of confusion for English learners.

擦音让很多英语学习者感到困惑。

In today's program, we will explore fricatives.

在今天的节目里，我们要探索擦音。

These are all fricatives, the sounds are coming out slowly and you hear this friction sound.

这些擦音，声音慢慢发出你听到擦声。

To be clear, fricatives mean there is a partial obstruction in the air stream.

说，擦音指的气流有一部分被阻滞。

Another type of consonant is a Fricative.

另一种辅音擦音。

First, when the thickened layers of the pericardium rub up against each other - it creates a friction rub which can be heard on auscultation.

当增厚的两层心包膜互相擦，可在听诊时闻及心包擦音。

It usually results in a friction rub, as well as ECG changes like ST elevation and PR depression, followed by T wave flattening and inversion.

通常表现出心包擦音，以及ST段抬高和PR段压低等心电图改变，继之呈现T波低平和倒置。

So, to make the th sound you already know, I hope that the tongue needs to be outside, and the air has to pass between the tongue and teeth in order to create this friction sound.

所以，要发出你已经知道的 th 音，需要舌头在外面，空气必须通过舌头和牙齿之间，才能发出擦音。