The Shortcut to Solving "I Can Hear It, But I Don't Understand It." 3 Scientific Reasons Why Shadowing Improves Listening Skills
Do you ever feel like you can hear every individual word in English, but the meaning of the whole sentence just doesn't sink in? If so, you are not alone. In fact, this is not due to a lack of effort or talent.
It is said that this phenomenon can be explained to some extent by the mechanisms of information processing in the brain.
What you will learn in this article: Why shadowing is effective for improving listening skills. Based on research data and expert explanations rather than personal anecdotes, I will explain this through three pieces of evidence.
Reason 1. Empirical Experiment at Kobe City University of Foreign Studies: Beginners Showed the Greatest Improvement
Ken Tamai of Kobe City University of Foreign Studies is known as a leading expert in shadowing research. In his lecture at the 3rd Annual Conference of the Japan Association for Interpreting and Translation Studies (2002), Tamai reported on two empirical experiments he conducted.
**Experiment A (1992, 3-month instructional experiment)** involved creating a group taught shadowing and a group taught dictation, and instructing them with the same materials for three months. The SLEP TEST created by ETS (an English proficiency test that serves as a precursor to the TOEFL) was used to measure listening ability.
As a result, the performance of the shadowing group improved. When the subjects were divided into three groups—high, middle, and low—based on their English proficiency, it was reported that the improvement in the low group (beginners) was the most prominent on the graph, and a statistically significant difference was confirmed in both the middle and low groups (there was no mention of a significant difference for the high group, as they likely had high scores to begin with and less room for improvement).
What Tamai focused on here was the point that "if knowledge (such as vocabulary) had simply increased, the high group should have improved more as well." In reality, the effect was greater in the group with lower English proficiency—this phenomenon is considered the starting point for research suggesting that "shadowing may be working on listening 'techniques and strategies' rather than knowledge itself."
Reason 2. Definitive Data Showing "Vocabulary Did Not Increase, But Repetition Ability Improved Dramatically"
Supporting this hypothesis is **Experiment B (6-day intensive class experiment)**. Intensive shadowing instruction was conducted for 2 hours each morning for 6 days, and multiple indicators were measured before instruction, on the 4th day, and on the 6th day, and compared with a control group.
The results were clearly divided depending on the indicator.
Listening ability: Statistically significant improvement
Vocabulary: Almost no change in either the shadowing group or the control group
Repetition ability (the ability to accurately repeat heard audio): Improved most dramatically among all indicators. It grew rapidly from the first to the second measurement, with a very strong statistical significance
Articulation speed: Significant improvement (though not large)
Digit memory span: No significant difference
In other words, even with shadowing, vocabulary does not increase. Yet, the ability to accurately process audio (repetition ability) improves significantly. This is data that supports, with numbers, that shadowing is not a "study method for memorizing knowledge" but "training to hone the skill of processing sound itself."
The relationship between this "sound processing" and "meaning comprehension" is explained in multiple studies and expert commentaries as follows: Listening is divided into two stages: (1) "phonological perception," where sounds are recognized as words, and (2) "meaning comprehension," where words are connected to construct meaning. The idea is that these two compete for the same cognitive resources in the brain.
For example, suppose a beginner hears the sentence, "Could you walk me through this?" They use up almost all their cognitive resources just picking up the sounds "Could...you...walk...me...through...this," leaving no remaining capacity to assemble the meaning, "It means to explain step by step." This is explained as the true nature of the state of "hearing it but not understanding the meaning." The core of this explanation is that as you continue shadowing and the processing in (1) becomes automated, the remaining capacity available for (2) increases, allowing the meaning of the same sentence to sink in easily.
Reason 3. Repeatedly Training "Memory That Disappears in About 2 Seconds"
There is one more explanation based on the psychological theory of working memory (Baddeley's model) that is worth noting.
Auditory information that enters through the ears is temporarily placed in a storage area in the mind called the "phonological loop," but it is said to disappear in about two seconds. It is a mechanism where information is finally retained by repeating it in your head (rehearsing) before it fades away.
Taking the earlier example of "Could you walk me through this?", if you cannot repeat it in your head the moment you hear it, the first part "Could you walk" is already starting to fade from the phonological loop while you are processing the latter part "through this"—this is explained as one of the reasons why it becomes harder to hear as sentences get longer.
Shadowing is a training exercise where you immediately chase the heard audio by speaking it aloud. In other words, it can be said that this activity repeatedly trains the "phonological loop rehearsal function" itself using actual English audio.
Starting today: Just one sentence is enough
Now that you understand the logic, what you can try starting today is surprisingly simple. Choose just one sentence you like from the materials you are currently working on, shadow it three times while being conscious of the meaning, and then stop the audio to check if you can say that one sentence on your own. You don't need to complete the whole text. In terms of training your "ability to process sound," carefully repeating one sentence is actually a shortcut.
Summary: 3 points to take away
☑️ Experiment A (1992, 3 months): With shadowing instruction, the lower the English proficiency level, the greater the improvement in listening skills, and statistically significant differences were confirmed in the middle and lower groups.
☑️ Experiment B (6-day intensive): While vocabulary skills remained almost unchanged, only repetition ability (the sound processing itself) improved dramatically.
☑️ Mechanism: Auditory perception and meaning comprehension compete for cognitive resources, and shadowing is explained as training to automate the former to free up capacity for the latter. In addition, it is also an activity that trains the rehearsal function of the phonological loop itself, which disappears in about two seconds.
Continuing with the feeling that "it seems like it might work" versus knowing "it works for these reasons and based on this data" should change how you approach your practice.
Lastly, just a little bit more. Actually, I, the person writing this article, operate a shadowing learning service called "Shadowing Library." It is a service that allows you to use your favorite videos on YouTube as shadowing materials, complete with English text and Japanese translations. Please feel free to take a look.
https://shadowing-library.com/about.html