Your perception of loudness bends to what you know, according to fascinating new psychology research

A new study published in the Journal of Cognition provides evidence that what we know influences what we hear. Researchers found that when people listened to pairs of words and nonsense words spoken at the same volume, they tended to judge the real words as louder. This perceptual bias appeared not only in a person’s native language but also in their second language, although with some differences in strength. The findings suggest that familiarity with language can shape basic aspects of auditory perception, such as loudness.

The researchers were interested in whether a previously documented visual illusion—where familiar letters and words are perceived as physically larger than unfamiliar combinations—also occurs with sound. In other words, could the brain treat known words as perceptually “louder” in the same way it treats them as visually “taller,” even when there is no physical difference?

This question connects to larger theories in cognitive science about how perception is influenced by prior knowledge. In particular, models of language processing suggest that top-down processes, like recognizing a word, can shape the way basic sensory features are experienced. The team wanted to know whether this effect could cross sensory boundaries, extending from vision into hearing.

They also wanted to test whether this effect depends on how familiar someone is with the language. For example, would a person hear a native-language word as louder than a foreign one? And would the effect be weaker when listening to a second language, where vocabulary is less deeply ingrained?

“We were inspired by earlier findings of the word/letter height superiority illusion in vision (New et al., 2016), where letters and words are perceived as taller than pseudoletters or pseudowords (letter strings that follow the orthographic and phonotactic rules of a language but have no meaning, e.g., wug) of the same size,” said study author Boris New, a professor in cognitive psychology at the Université Savoie Mont Blanc, LPNC.

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“We wanted to know whether this illusion was specific to reading (and perhaps to the visual word form area) or whether it reflected a more general cognitive mechanism that could also be observed in other modalities like audition. The study connects also to an everyday phenomenon – many people feel they need to ‘turn up the volume’ when watching movies in a foreign language. We wanted to test whether this subjective experience has a perceptual basis: do words in a familiar language actually feel louder than in a less familiar one, even when their physical intensity is identical?”

The researchers ran two experiments. In the first, they recruited 77 native French speakers who also spoke English as a second language. In the second, they tested 89 native English speakers who had some knowledge of French.

Participants listened to pairs of audio clips in which two spoken items—a real word or a nonsense word made by swapping the syllables of a real word—were played one after the other. The key trials involved pairs where the two items were played at exactly the same volume, yet one was a real word and the other was not. The participants’ task was to decide which of the two items sounded louder.

The nonsense words were carefully constructed to resemble real words in terms of their syllable structure and length, but they lacked meaning. This allowed the researchers to control for acoustic features and focus on the effect of lexical familiarity. The sounds were presented in both the participants’ native and second languages, with the language blocks counterbalanced to avoid order effects.

Participants first completed a headphone check and a calibration step to ensure consistent listening conditions. Then they practiced with example trials to familiarize themselves with the task. The full experiment involved several trials in which the words varied in their actual volume or were equal in volume. The key measure was whether, in trials where the volume was objectively the same, participants were more likely to say the real word sounded louder than the nonsense word.

In Experiment 1, the French-speaking participants showed a clear pattern. When real words and nonsense words were played at the same volume, they were significantly more likely to judge the real words as louder. This happened in both their native French and their second language, English. However, the effect was stronger in their native language. When errors were made in identifying which item was louder, over 70 percent of those errors favored the real word in French, compared to about 59 percent in English.

Experiment 2 replicated the basic finding with a different group: native English speakers. These participants also showed a bias to hear real words as louder than nonsense words. Interestingly, though, the strength of the effect was similar in both their native English and their second language, French.

“We expected the illusion (words being perceived as louder than pseudowords) to be stronger in the native language (L1) than in the second language (L2) for both groups,” New told PsyPost. “That’s what we found with French participants (illusion was stronger in French than in English). But for English participants, the pattern was different: the illusion was present in both English (L1) and French (L2), but the strength was about the same in both languages, not stronger in L1 as predicted.”

“This was surprising because it went against the initial hypothesis. We think it might be due to how the stimuli were created: syllables were concatenated, which disrupted natural stress patterns, a crucial cue in English but less so in French. That could have weakened the ‘native-language boost’ for English listeners.”

The team examined whether differences in second-language proficiency could explain this asymmetry. Data showed that French speakers reported using English more frequently and rated themselves as more proficient in it than English speakers did with French. This suggests that the level of experience with a language might influence the strength of top-down processing effects.

Taken together, these findings suggest that language knowledge influences perception in a direct way. Words that are familiar to the listener are more likely to be perceived as louder than nonsense words, even when there is no actual difference in volume. This provides support for theories that top-down processes—where knowledge and expectations feed back into early sensory processing—can shape how we perceive the world.

“The key takeaway is that our brains don’t just passively register sounds – what we know and recognize shapes how we hear them,” New explained. “Words we know are literally perceived as louder than nonsense words, even when the physical volume is the same.”

“So the big message is: familiarity with language changes how we actually perceive sound intensity, our knowledge literally shapes our perception. Readers should think of the effect as modest in size but revealing of an important principle: the brain’s expectations and knowledge can change how loud something feels. The illusion is subtle, not dramatic; the effect is a small perceptual bias. So it’s not that your ears are changing physics, it’s that your brain’s language system nudges your perception.”

But the study, like all research, has some limitations. The stimuli were synthetic and constructed from individual syllables, which may have disrupted natural speech rhythm, especially in English. Future studies could explore whether the illusion holds with naturally spoken words and across a wider range of languages.

The task was also demanding, and the experiment was designed to be completed in under 20 minutes, which limited the number of test words. Expanding the range of stimuli would help confirm whether the effect generalizes beyond the specific examples used here.

Individual differences in hearing sensitivity were not directly measured. Although participants adjusted their listening volume at the start of the study, this method relies on self-assessment and may not capture subtle differences in auditory processing. Future work could include more precise hearing tests.

Another avenue for research would be to test this auditory illusion in other syllable-timed languages. If the effect varies across languages, it might reveal how speech rhythm and lexical familiarity interact in shaping perception.

“We would like to replicate the experiment in other syllable-timed languages like Italian, to see if the illusion generalizes the same way it does in French,” New told PsyPost. “Our study helps explain a very common experience, why people often feel the need to turn up the volume when listening to a foreign language. It shows that this isn’t just about effort or attention, but about how our brain’s familiarity with words literally changes perception.”

The study, “Listening to Foreign Languages: Pump Up the Volume!,” was authored by Boris New, Clément Guichet, Elsa Spinelli, and Julien Barra.