The shadowing technique for improving your Spanish is a wonderful tool that has been developed by professor Argüelles. It consists of repeating out loud what a native speaker says (exactly at the same time as the native speaker). A pair of headphones are usually used, given that it provides a greater feeling of immersion and quality sound. The use of this technique provides multiple benefits. Among them, you gain more fluency with the language, your intonation improves enormously, as well as your pronunciation (although, from my point of view to a lesser extent).

You can use the shadowing technique in different ways:

Reading aloud while you listen to the native speaker.

Blind shadowing, where, you are not reading the text while you listen and repite aloud.

Blind shadowing is much more effective for improving the pronunciation and intonation. That is the one I recommend to students whose level is at least intermediate.

For those students with lower levels, it might be recommended to start to practice the technique while you read at the same time.Iit is important that you look for audios according to your level of Spanish, otherwise, you will have problems  understanding most of what is said. I recommend that you  shadow a person of the same gender as you, so that you gain the inflection, musicality, tonality, etc of a person of the same gender (Take into account that the intonation, musicality and warmth while talking usually differs quite a lot between a man and a woman).

A very easy way of implementing these technique is downloading a podcast and its text. Read the text first and then repeat  what it is said out loud at the same time as the native speaker, without reading the text. I have used this technique many times to improve my spoken English level. While I drive I listen to podcasts about subjects I am interested in. Listening and repeating them aloud while I drive.

This will  not only improve your level of fluency in Spanish, but  you also will learn about many interesting subjects in Spanish.

I strongly recommend this technique. It is possible that using this technique alone will not be enough to master Spanish, but it can contribute enormously to improving your Spanish fluency. This technique has allowed me to improve my fluency when speaking English, particularly with respect to improve my intonation. I have met several people who have used this technique to improve their pronunciation and intonation in Spanish with great results.