Chemistry Demos

Auditory Risk of Chemistry Demonstrations

Dr. Jeff Macedone, of the BYU Department of Chemistry and Biochemistry, approached us about making measurements of exploding balloon demonstrations that were highlights in chemistry lecture courses and in popular outreach shows.  These balloons, usually filled with stoichiometric mixes of hydrogen and oxygen or acetylene and oxygen,  create a large acoustic impulse.  Because sound levels over 140 dB can be instantly damaging to the ear, it is important to characterize the balloons in order to quantify auditory hazard and develop safety guidelines.  We began a collaborative project that began with the hydrogen-oxygen balloons, and then moved to the acetylene-oxygen balloons, and then to other demonstrations, such as methanol cannons and nitrogen triiodide mixes.  We found that many demonstrations exceed the 140 dB threshold at reasonable distances and therefore require hearing protection, larger audience standoff distances, or other mitigative measures.  We emphasize that each of these demonstrations continue to be performed at BYU and the purpose of our papers was to simply demonstrate the need for caution. In many courses, we purchase earplugs in bulk and the students are trained on their proper use before handing them out and doing the demonstrations.


A number of publications resulted from this work.  The two that summarize the auditory hazards are published in the Journal of Chemical Education:

  • K. L. Gee, J. A. Vernon, and J. H. Macedone, “Auditory risk of exploding hydrogen-oxygen balloons,” J. Chem. Educ. 87, 1039-1044 (2010)

  • J. H. Macedone, K. L. Gee, and J. A. Vernon, “Managing auditory risk of acoustically impulsive chemistry demonstrations,” J. Chem. Educ., 91, 1661-1666 (2014).

Due to publisher restrictions, these are not available as full-text downloads on my Publications page, but contact me for a copy if you don't have access through your institution. 

Other publications that describe further acoustical characteristics of the two types of balloons are:

  • J. A. Vernon, K. L. Gee, and J. H. Macedone, “Acoustical characterization of exploding hydrogen-oxygen balloons,” J. Acoust. Soc. Am. 131, EL243-EL249 (2012). 

  • M. B. Muhlestein, K. L. Gee, and J. H. Macedone, “Educational demonstration of a spherically propagating acoustic shock,” J. Acoust. Soc. Am. 131, 2422-2430 (2012).

These two articles are #51 and #53 on the  Publications page.