There are myriad sections without references. At other times the authors reference secondary sources (in discussing toilet training they note that "Pediatrician Lindy Woodard believes that a child can and should be trained by thirty months; in her professional experience, children who are trained at an older age have more problems learning to use the toilet." p. 168). Often the subject of a section would lack focus and context, such as p. 209 where the authors talk about "soul disorders" in reference to mental health. One assumes they are referencing the work of someone else, but it isn't cited or put into context. This leaves the reader to wonder why the authors would consider if "wisdom teeth extraction impacts our souls."
The relationships between otoacoustic emissions and tinnitus have been explored. Several studies suggest that in about 6% to 12% of normal-hearing persons with tinnitus and SOAEs, the SOAEs are at least partly responsible for the tinnitus. Studies have found that some subjects with tinnitus display oscillating or ringing EOAEs, and in these cases, it is hypothesized that the oscillating EOAEs and tinnitus are related to a common underlying pathology rather than the emissions being the source of the tinnitus.