The treatment of prominent ears with otoplasty is a relatively common procedure. The International Society of Aesthetic Plastic Surgery estimated that over 242,000 otoplasties were performed worldwide in 2010 . At high volume institutions, otoplasty results in low rates of complications, and high cosmetic satisfaction .
By the age of 5 years, the growth of the cartilaginous pinna is almost complete . This corresponds to the age when many children begin school-based education, and may be subject to stigma and ridicule by their peers. While protruding ears may be considered a sign of good fortune by some Asians, in most other cultures, they are associated with feelings of anxiety, social discomfort, and even abnormal behavior .
While Down syndrome and Turner syndrome may be associated with both prominent ears and conductive hearing loss, prominent ears are not generally thought to be associated with hearing issues. As well, many surgeons who perform otoplasties are unaware of any hearing related consequences with respect to the protruding ears. Thus, prominent ears in a child is not in itself an indication for any type of audiometric evaluation. This has led to the absence of any studies being conducted in this particular area.
In this surrogate study, we investigated the effects of temporary changes in the forward position of the pinna on speech intelligibility and reception in normal hearing adult subjects. While otoplasty is more commonly performed in children, adults are more cooperative and reliable subjects; they are better to accommodate a long battery of audiologic tests. While it is unlikely that the purely acoustic effects of pinna position vary from adults to children, further testing in a pediatric population is necessary to confirm the present results.
Although the function of hearing has traditionally been considered unimportant and unaltered in otoplasty procedures, this has simply been an assumption. As hearing and speech development occurs early in life and since otoplasty is performed mainly in young children, it may be important to understand how, if at all, this procedure may affect auditory function.
If “normalizing” the shape of the ear is found to affect auditory perception, this may have consequences to the child functioning in noisy environments, and maybe something further to consider in the informed consent, and risk/benefit assessment.
The shape of the pinna is thought to contribute to vertical sound localization in humans by providing monaural spectral cues. Hofman and Opstal  used pinna-shaping molds to demonstrate that localization accuracy is degraded with changes to the pinna, but this skill was reacquired over time. As vertical localization has limited utility in humans, we chose not to investigate this phenomenon as part of our study. Also, while the brain can learn to reinterpret changes in the acoustic frequency shaping that altered pinna may cause, and relearn localization cues, changing the pinna shape will reduce or improve the S/N ratio, which cannot be compensated for by central mechanisms. It is true, however, that portion of release from masking that occurs because of central binaural processing might be reacquired through relearning.
Our findings demonstrate a statistically significant difference in speech intelligibility. However, it is difficult to precisely quantify the degree of noticeable change in a real world scenario. It is likely to be small in the practical sense. Furthermore (although not tested in our study), there may be an adaptability to the changes in hearing after otoplasty surgery, which may affect long-term outcomes. Potential adaptation might occur in a manner similar to Hofman and Opstal’s vertical sound localization study  previously discussed.
Again, we found that a pinna in forward position results in a statistically significant improvement in speech intelligibility when the speech is introduced at -45° from anterior. Further investigation may find that a forward pinna may be disadvantageous for understanding speech introduced from behind. Yet, in most real world scenarios, the sound source of interest is in the front hemifield (e.g. facing your conversation partner). We chose to focus on this more likely test condition, but it is important to acknowledge that there may be scenarios in which improved rear speech intelligibility may be beneficial with the pinna in non-protruded position (e.g., hearing people in the backseat while driving a car).
This is the first study to assess any aspect of auditory function with respect to changes in pinna position. Future research may investigate children undergoing the actual otoplasty procedure, to assess both the immediate auditory effect and the long-term hearing function and possible adaption.
During conduction of the SII and HINT tests, neither the tester nor subjects were blinded to pinna position.
For cases of otoplasty where a conchomastoid suture is placed, there may be slight narrowing of the external auditory canal meatus. This possible effect was not reproduced in the study population and therefore, may confer the results ungeneralizable to those patients who receive the conchomastoid suture. Yet the incidence of significant meatal stenosis after otoplasty is extremely rare and therefore, this particular effect is deemed to be negligible.