Time-frequency analysis of transient-evoked otoacoustic emissions in children exposed to carboplatin chemotherapy

The aims of this study were to characterize and quantify time-frequency changes in transient-evoked otoacoustic emissions (TEOAEs) recorded in children diagnosed with retinoblastoma who were receiving carboplatin chemotherapy. A signal processing technique, the wavelet transform (WT), was used to analyze TEOAE waveforms in narrow-band frequency components. Ten children (aged 3-72 months) diagnosed with unilateral or bilateral retinoblastoma were enrolled in the study. TEOAEs were acquired from the children with linear sequences of 70 dB peak equivalent SPL clicks. After WT analysis, TEOAE energy, latency and normalized energy in the narrow-band frequency components were compared before and during carboplatin chemotherapy treatment (average dose 1693 mg/m²). On a group basis, no significant differences (p > 0.05) in the TEOAE energy, latency or normalized energy before and after carboplatin treatment were observed. There were decreases in normalized energy on an individual basis in 10 out of 18 ears in the sample. Exposure to carboplatin chemotherapy did not cause significant changes in TEOAE energy, latency and normalized energy during treatment. However, long-term monitoring of hearing with measurements of TEOAEs is warranted, given the risks of delayed hearing loss in some children receiving carboplatin chemotherapy.