The prevalence of spontaneous otoacoustic emissions (SOAEs) was measured in a group of 100 neonates and in a group of 50 normal-hearing young adults. The prevalence of SOAEs in the adult group (0.62) is at the high end of the range of prevalences reported in other surveys of adult SOAEs based on measurements using similar microphones. The prevalence of SOAEs in neonates (0.64) is not significantly different from that in adults. The various tendencies that have been found to be significant in the pooled results of other surveys are also evident in our adult group: more SOAEs in right ears, a higher prevalence of SOAEs in females, and a dependence between ears for the occurrence of SOAEs. The above-mentioned tendencies are also significant in the infant data. The major differences between the infant and adult results are the predominant SOAE frequency range and the average levels of SOAEs. The majority of adult SOAEs are between 1.0 and 2.0 kHz, whereas the majority of neonatal SOAEs are between 2.5 and 5.0 kHz. The average SOAE level is −2.6 dB SPL for adults and 8.5 dB SPL for infants.