In children aged 0 to 7 years, behavioral evaluation during cochlear implant programming is often difficult or unreliable. Objective, reproducible, and rapid markers are therefore essential. While objective measures such as ECAP (electrically evoked compound action potentials) help guide safe programming, they can show inter-electrode and inter-subject variability. Electrically evoked stapedius reflex threshold (eSRT) has emerged as a relevant objective marker to approximate the comfort level of stimulation.

Pediatric studies indicate that eSRT can be measured in the majority of children, closely corresponds to the comfort level, and is associated with improved speech outcomes when programming is guided by eSRT. In our previous single-center study in children aged 8 to 17 years (N=30; 44 implanted ears), eSRT was obtained in 83.3% of patients, with strong correlation between C-subjective and C-eSRT thresholds (r>0.94; p<0.001) across all electrodes. Tonal performance remained stable, and speech intelligibility, particularly in noise (FraSiMat), significantly improved with an eSRT-based program after one month of habituation. Daily device use remained stable, reflecting good clinical acceptability. These results support the relevance of systematic integration of eSRT in routine programming.

The aim of the eSRT2 study is to evaluate the feasibility and reliability of eSRT measurement in real-world clinical care for children aged 0 to 7 years, and to monitor its stability during post-operative follow-up. Improved auditory accessibility and better-controlled acoustic comfort through eSRT are expected to accelerate speech development in children by enabling earlier improvements in vocal performance and intelligibility.

Cochlear implant programming relies on determining the patient's auditory dynamic range. This corresponds to identifying, for each electrode, the threshold of first perception (T-level) and the most comfortable level of stimulation (C-level or MCL), which defines the functional stimulation range. Different implant manufacturers (Advanced Bionics, Cochlear, Med-El, Oticon Medical) provide specific recommendations for estimating these upper stimulation levels.

Programming can be performed using behavioral measures or objective measures. Behavioral methods, based on patient responses, are widely used in adults. In children and in patients with associated pathologies, behavioral measures are often difficult due to limited auditory experience and potential confusion between loudness and pitch perception.

Therefore, objective measures are recommended in pediatric populations to assist in programming. ECAP/EAP measures are commonly used but show variable performance depending on the measure and implant manufacturer

Another objective measure, the electrically evoked stapedius reflex threshold (eSRT), shows a strong relationship with comfort levels (C-level/MCL) in both adults and children. eSRT appears to be a relevant tool for guiding programming, especially when subjective measures are limited. Recent studies have optimized the protocol (probe frequencies, reproducibility criteria) and confirmed its feasibility , including in pediatric populations using high-frequency probes (Palani et al., 2022) and normative data in children (Aini, 2022). Combined approaches using ECAP and eSRT to estimate C-levels/MCL are also emerging in pediatric programming .

Functionally, better estimation of the comfort level improves auditory accessibility, which is associated with enhanced speech perception and vocal performance. Over the long term, this supports faster language development in children implanted early.

Our previous eSRT study in children over 8 years old demonstrated a strong correlation between C-subjective and C-eSRT thresholds, and improved speech intelligibility (particularly in noise, FraSiMat) with eSRT-guided maps. These findings support the integration of eSRT into routine programming for pediatric populations.

Inclusion Criteria:

• Child aged 0 to 7 years
• Unilateral or bilateral cochlear implant
• Normal tympanogram
• No objection from either parent or legal guardian

Exclusion Criteria:

• Severe neurological disorder present before inclusion (identifiable by MRI and/or pediatric neurological assessment)
• Unstable middle ear pathology on the day of inclusion (e.g., acute serous otitis, tympanic membrane perforation)
• Documented abnormality or lesion of the facial nerve or stapedius muscle
• Severe cognitive, psychiatric, or developmental delay at the day of inclusion
• Family not fluent in oral French.

The target population is pediatric children aged 0 to 7 years followed at a specialized center (Necker Hospital, Paris). In children under 7, cooperation with behavioral testing is often limited, making the use of robust objective markers crucial (Gordon et al., 2004).

Pediatric data suggest that eSRT can be measured in the majority of children and corresponds closely to the C-level (Lorens et al., 2004; Bresnihan et al., 2001; Aini, 2022), with recently optimized protocols (Palani et al., 2022; Wolfe et al., 2017).

The study includes children with unilateral or bilateral cochlear implants, across all implant manufacturers, reflecting real-world practice.

Exclusion of children with unstable middle ear pathology reduces the risk of false-negative eSRT results related to tympano-ossicular transmission.