## 1 Introduction
Using customized equipment, HF (up to 16 kHz) DPOAEs have been measured [5; 48] and are repeatable across testing sessions in normal-hearing young adults and children [5; 50; 51; 52], in those with cystic fibrosis tested between ototoxic treatments [51], and identified the earliest signs of damage at the highest frequencies with present DPOAEs in adults exposed to ototoxic agents [53], but have not been recorded in newborns. While DPOAEs may not be recorded at the highest frequencies of human hearing for each individual based on their cochlear health, it is imperative to monitor the highest frequencies with a response in individuals exposed to ototoxic agents to identify the earliest signs of damage [53; 54]. For clinical applications, this may necessitate that higher stimulus levels, varied stimulus frequency ratios, and criteria defining a present DPOAE may be altered to maximize monitoring capabilities at the highest frequencies for each individual. As spontaneous otoacoustic emissions (SOAEs) show sensitivity to cochlear damage, are present in newborns, occur at higher frequencies in newborns compared to adults, and can influence DPOAE levels [16; 55; 56; 57], SOAEs should be measured continuously as well in monitoring programs. SOAEs are sounds recorded from the inner ear without external stimulation. SOAEs arise from active cochlear mechanisms and can influence DPOAE recordings. Those with SOAEs had significantly greater DPOAE levels compared to those without detectable SOAEs in adults [16; 58] and infants [16]. Given that SOAE presence has significant effects on DPOAE responses, the effects should be considered in clinical applications of DPOAE measurements. SOAE levels range between \(-\)18 to 25.5 dB SPL ([56; 59]) and decrease with increasing age [60; 61; 62]. [PERSON] [62] reported SOAE levels as high as 29.3 dB SPL in children and 30.4 dB SPL in infants. SOAEs recorded in infants, children, and adults, typically occur within the frequency range of 1-5 kHz [63; 64; 65] and the average number of SOAEs per ear is reported to be between 2 to 3 emissions [62; 65]. As age increases, the frequency range of SOAEs tends to decrease [61; 65; 66; 67]. In children and infants the majority of SOAEs are recorded between 2.5-5 kHz, whereas in adults most SOAEs are recorded between 1-2 kHz [60; 61; 62; 64]. Less often, SOAEs have been reported at frequencies of 7 kHz and higher [59; 68]. The lack of recording higher-frequency SOAEs may be related to limitations of some clinically available instruments with a 6.25 kHz upper frequency cutoff [69]. Asymmetries in the number of SOAEs recorded between ears exist in children and adults, with significantly more SOAEs recorded in the right ears of subjects with unilateral or bilateral SOAEs [56; 56; 60; 67; 66; 71]. Also, gender differences are apparent in infants and adults, with the prevalence and level of SOAEs greater in females compared to males [62; 65; 71; 72; 73]. While these differences between ears and gender for SOAEs remain unexplained, [PERSON] [74] suggests that these findings might be related to less efferent inhibition in females and in right ears. Additionally, some studies report that females tend to have more SOAEs than their male counterparts [61; 66; 55]. When recording SOAEs in newborns, [PERSON] et al. [55] reported that 56.7% of newborn ears exhibited SOAEs and they occurred at higher frequencies than adults. More recently, [PERSON] et al. [54] reported that 85% of newborns have at least one SOAE, with an average of four to five SOAEs per emitting ear. Overall, a high percentage of newborns exhibit SOAEs and this measurement should not be ignored when recording cochlear responses. The purpose of this study is to measure and determine the repeatability of HF DPOAEs in newborns and assess if there is an influence of calibration technique, in-the-ear SPL versus FPL, on the measurements. Given a high percentage of newborns exhibit SOAEs, which can influence DPOAE measures, SOAEs were recorded as well [75].