Safety – Are Resonance Rods Harmful to Hearing?

Question to the STAO Safety Committee

Can resonance rods do damage to a person’s hearing, especially if the demonstration is repeated several times during the day?


Tanya Malusev from Arbour Scientific measured the sound intensity. The maximum value achieved was 85 db. The frequency (not determined by them) occurs in a range of 2500 to 5000 Hz. OSHA indicates that habitual exposure to intensities can cause hearing damage. They published the following table:

8 hours at 90 db
4 hours at 95 db
2 hours at 100 db
0.5 hours at 110 db

The Canadian Centre for Occupational Health and Safety has also published a similar table listing sound intensity levels as they relate to hearing damage. As I interpret this, the resonance rods, while irritating (at this high frequency), will not do any damage to students/teachers at 85 db for such a short duration. This same interpretation was supported by Tanya (Arbour Scientific) in a personal email to me.

I hope that this information will be useful in making an informed decision as it relates to this particular demonstration. If new information is brought to your attention regarding this demonstration, I encourage you to share that with our committee. Please do not hesitate to contact us with further safety inquiries.

Click on the following link for a demo that illustrates the use of resonance rods