Minimal hearing loss in children: effect on speech in noise perception

Background: Minimal hearing loss (Mhl) is a relatively underappreciated pathological entity encompassing three types of sensorineural hearing loss, based on audiometric evaluation Unilateral hearing loss (Uhl), mild bilateral hearing loss (MBhl), high-frequency hearing loss (hFhl). the condition is quite common in the pediatric population and does not have a single cause, but rather a wide range of possible etiolo- gies. Mhl may go unnoticed by parents and can manifest indirectly with speech delay and poor school performances. it is also associated with difficulties in speech perception, particularly in environments with background noise and reverberation. Speech audiometry evaluation is there- fore crucial, not only to make a timely diagnosis but also to guide treatment and provide important cues on child’s progression and rehabilitation. A recently validated test for the evaluation of children’s speech reception threshold (SRT) is the Simplified Italian Matrix (ItaMatrix) Test that allows to evaluate the speech intelligibility in noise in an adaptive way. In the present study, we used the ItaMatrix test to evaluate how mild hearing loss could affect speech recognition in children in comparison to a group of normal-hearing peers. Methods: We enrolled 47 patients between 6 and 13 years old referred to our ENT Unit for Learning disabilities. An exclusion criterion was any previously known behavioral or physical condition affecting the child that can worsen the academic performances, such as hyperactivity or dyslexia. First, the children underwent pure-tone audiometry (PTA) subsequently, we evaluated the speech-reception threshold (SRT), in quiet (SRTq) and noise (SRTn) using the ItaMatrix test. Results: We found that 28 children had normal hearing (group 1) and 19 had a hearing loss. among the hearing loss group, we decided to only consider the bilateral hearing loss children (group 2, N.=7) for homogeneity of analysis. Pta, Srtn, and Srtq were higher in group 2. the correlation between Pta and Srtn appears to be stronger in group 2, suggesting that a noisy environment is a more pressing challenge for the child with hearing loss. Age influences the SNRn in both groups but appears to correlate more with SRTn than SRTq, reflecting the fact that the maturation of the brain network makes a greater contribution in hearing with background noise than quiet. The impact of MHL is particularly important when considering the school environment, typically a noisy class, where the signal intensity decreases moving away from the teacher while background noise, coming from different sources, remains constant (squires 2016) at about 65 dB. Conclusions: Our study supports the evidence that children with Mhl require a more favorable signal-to-noise ratio to process the acoustic signal effectively and keep up with their peers in school.