Imagine trying to concentrate on a teacher's instructions while surrounded by classmates' chatter or the air conditioning's hum. This scenario is common in classrooms and poses a significant challenge for students, particularly young children. A recent study by researchers at RWTH Aachen University sheds light on how different levels of noise affect the mental effort required to listen and understand speech, known as "listening effort." Our study at RWTH Aachen University aimed to understand this phenomenon better, particularly among children aged six to ten and young adults.

Listening effort is defined as the cognitive resources required to comprehend speech, especially in challenging auditory environments. It involves perceptual, attentional, and cognitive processes that become more demanding when background noise is present. This increased demand can hinder students' ability to process spoken information effectively, impacting their learning outcomes. To explore listening effort, we employed a dual-task measure - a method that requires participants to perform two tasks simultaneously. This approach is based on the theory that our cognitive resources are limited, so engaging in one task can affect performance on another. The dual-task measure consists of two tasks, a primary task where the main focus is directed and a secondary task where it is hypothesized that performance decreases when the task load increases. In our study, the primary task involved word recognition, where participants matched spoken words with pictures. The secondary task was a digit recall exercise, requiring adults to remember sequences of seven digits and children five digits. This task combination was chosen because both tasks draw from similar cognitive resources, considering it an effective measure of listening effort. Additionally, both tasks are like typical classroom activities.

Our study involved 44 primary school children and 25 young adults. We created realistic classroom noise scenarios using multi-talker babble noise - a recording of several people talking at once - to mimic the chatter of a busy classroom. We tested two signal-to-noise ratios (SNRs): 0 dB and -3 dB. An SNR of 0 dB means that the speech and background noise are at the same volume level, while -3 dB indicates that the background noise is slightly louder than the speech. These conditions were tested in both anechoic (soundproof) environments and acoustically simulated classrooms with typical room effects like reverberation.

In addition to the dual-task measures, we used a questionnaire to capture participants' subjective experiences of listening effort. After each experimental noise condition, participants answered questions about their well-being during the tasks, their perceived performance, and how effortful they found the tasks. These responses were rated on a five-point scale and provided valuable insights into how individuals felt about their listening challenges.

Our findings revealed that children showed greater difficulty with word recognition tasks under challenging noise scenarios compared to adults. This indicates that their auditory processing systems are still developing, making them more susceptible to the disruptive effects of background noise. Additionally, we found that all age groups experienced increased subjective listening effort in noisy environments compared to quiet ones. Notably, the dual-task measure effectively captured significant differences in third- to fourth-graders in behavioral listening effort across various noise scenarios, indicating their heightened sensitivity to background noise. Interestingly, we found a correlation between subjective perceptions and behavioral listening effort for third- to fourth-graders and adults. This suggests that self-judged perception can align with measurable changes in performance, reinforcing to use both measures to assess listening effort. By understanding how noise affects word recognition and listening effort, educators can develop strategies to create more conducive learning environments that minimize cognitive strain on students. This can involve considering installing soundproof panels in classrooms or adapting didactic concepts. In summary, the study emphasizes that while adults have more established auditory processing capabilities, children are still developing these skills. This ongoing development affects their ability to recognize words and manage listening tasks in noisy settings, pointing to the necessity for supportive learning environments that mitigate these challenges.