(Inside Science) -- When Mickey Rooney, playing a Japanese man, exclaims "Miss Gorightry!" in the 1961 film "Breakfast at Tiffany's," his stereotypical accent might make modern audiences cringe. But it might also make them wonder -- why is it so difficult for people to hear or produce certain sounds from a foreign language? For instance, can you hear the difference between the eight different types of "d" and "t" sounds in Hindi, or produce the nine different tones in Cantonese?
A new study on Dutch native speakers learning to distinguish "a" and "e" sounds in English provides yet another example of how complicated the process of learning new sounds in a foreign language can be.
Shut up and listen?
"The problem starts when you want to learn a foreign language but you're not able to tell certain sounds apart because those differences are not relevant in your native language," said Jana Thorin, a psychologist from Radboud University in the Netherlands and author of the paper.
According to Thorin, when we try to learn a new language as adults, we tend to map new sounds to sounds we already know in our native language. Although we can still learn to hear and produce entirely new sounds with enough training, we may develop bad pronunciation habits early on that are difficult to fix later.
This may explain why people can have nonnative accents even after learning to speak a new language fluently and being immersed in it for decades, said Melissa Baese-Berk, a linguist from the University of Oregon in Eugene not involved in the study.
For instance, it may be counterproductive for a native Japanese speaker learning English to try to pronounce "l" versus "r" sounds before being able to hear the difference between the two. Previous studies have shown examples where learning to perceive and produce new sounds at the same time can negatively impact learning, but the latest study by Thorin and her team shows that this is not necessarily true.
In their study, they trained native Dutch speakers to hear and produce the differences between "a" and "e" sounds in English words such as in "pan" and "pen," one after another, and found that perception training helped the learners better produce the sounds, while production training does not help or harm the learners' ability to hear the sounds.
Bottom line: It depends
"There are studies that show disruptions, and studies that show benefits, and also some that show no correlations between the two at all," said Baese-Berk. Her own study from 2016 that examined native Spanish speakers learning Basque was an example that showed a negative effect when learners try to hear and produce new sounds at the same time.
These differing results demonstrate the complexity of the problem, according to Baese-Berk. Linguists and psychologists are still trying to sort out the many factors that influence whether or not combining perception and production training can aid learning, she said. Thorin also thinks that in order for the combined training to have a positive effect, the learners would need feedback.
Another factor that may have contributed to the positive effect could be the fact that the native Dutch speakers were already quite proficient in English prior to the training, said Baese-Berk. This could have led to a lower cognitive load when learning, such that the listening and speaking practices acted more like mutual reinforcements rather than strenuous distractions.
Language learning is a complicated process that varies from person to person and depends on multiple factors such as the learner's age, the similarity between one's native tongue and the target language, and the quality of the training.
So, should you try to learn to hear new language sounds before speaking them, or tackle both tasks at the same time? While researchers continue to tease out the details of how all these factors interact, they remain cagey about offering advice.
"I need a T-shirt that on one side says 'both' and on the other side says 'it depends.' Because for most of these binary questions, those are going to be my answers," said Baese-Berk.