More on Eardrum Rupture

My last blog related to the pressures at which an eardrum was susceptible to rupture and then also to be relatively assured that eardrum rupture would occur.  But, what was missing?

In response to this I received an e-mail from one of my good engineering friends, Steve Armstrong, who asked me why I had not included something that would have been helpful, and which should have been obvious to me.  Why did I not relate the eardrum rupture to sound pressure level (SPL) – something that many of the readers might have a better concept of – rather than to Pa, kPa, psi, etc.?  How such a consideration escaped me is a testament to the fact that just because someone writes something, that it is assumed to have been taken to its logical conclusion.

What Steve pointed out so well is that there is nothing harder to see through than an assumption of completeness, until someone points out that the least questioned assumption is often the most questionable.  Or, paraphrased, sometimes one cannot see the forest because of the trees.

So, in order to “complete” the previous blog, I have added to the table from the last blog, a column to relate the various pressure levels to SPL.  This table is included below.  (I did stop at adding columns for dynes/cm2, however).  And, it was good to redo because I did find an error in the number posted for 100 mmHg.  The value should have been 0.75 rather than 0.00.  I would like to blame this error on any number of things, but in truth, it probably was due to carelessness.  In addition, I thought that it might be good to add a few sound level references in dB SPL to make the table even more meaningful.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Another form of potential eardrum rupture that has been offered relates to Hyperbaric Oxygen Therapy (HBO2).  It was not mentioned in the previous blog on the topic of eardrum rupture and I am not certain how it relates to the subject.  Originally developed to treat the “bends” of deep sea divers, it has become somewhat popular in recent years for the treatment of wounds (burn, trauma, soft tissue), infections (including infections of the bone), skin grafts, tissue damage from oncologic or radiologic treatment, extreme blood loss, and carbon monoxide poisoning {{1}}[[1]] Hyperbaric Oxygen Therapy (HB02). Tucson Audiologists/TAI Inc. blog, January 24, 2010, http://tucsonaudiologists.com.[[1]]  The blog was written because of an elderly patient who was undergoing this treatment and who had been fitted with PE tubes.  He had mentioned experiencing severe pain following the first treatment and did not want to continue.  He was referred to an otolaryngologist, treated, and then returned to the HB02 treatment, not knowing that the PE tubes had been inserted.  His complaint was that his hearing aid seemed to now be malfunctioning because he could not hear as well.  The question was, did the HB02 treatment create the severe pain he initially experienced?  Too many questions remain to draw any conclusions, but the relationship of it to hearing is something that will most likely be investigated, especially since HB02 treatment has been purported to be helpful, according to the blog author, for such conditions as sudden hearing loss, tinnitus, and multiple sclerosis. However, verification of these claims await verification.

About Wayne Staab

Dr. Wayne Staab is an internationally recognized authority on hearing aids. As President of Dr. Wayne J. Staab and Associates, he is engaged in consulting, research, development, manufacturing, education, and marketing projects related to hearing. Interests away from business include fishing, hunting, hiking, mountain biking, golf, travel, tennis, softball, lecturing, sporting clays, 4-wheeling, archery, swimming, guitar, computers, and photography. Among other pursuits.

1 Comment

  1. I think that a tympanometer induced pressure changes in the range of -200 to +400 mm H2O, not mm of mercury.

    Further, I think that there may be several types of TM ruptures, some related to the SPL of impact or transient sound and perhaps some related to constant pressures such as those encounter in the careless taking of an ear mold impression.

    I recall a rather simple study on cadaver ears, done in the late 1960s or the early 1970s, trying to establish the point at which these types of TM would rupture. This was conducted in response to some questions concerning “standard” tympanometry causing a TM perforation. I believe it was concluded that the pressures required were far beyond those delivered by a “standard” tympanometer. (Not many cadavers “volunteered for the study, and no “living” ears were tested as I recall.)

    I am aware of only one small study looking at 6 or so TM perforations allegedly caused in the process of taking an ear mold impression. (Wynne and Able, 1980 or so) It is certainly easy to understand why such data as TM perforations due to EMI are not available, but it would sure be interesting to know.

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