With apologies to Sigmund Freud, a cigar may be more than just a cigar.
John- not his real name. It’s actually Alex, but we will call him John- walks into my clinic for a musicians’ assessment. I no longer call it a “musicians’ hearing assessment” because I find that “hearing” is only one small part of it, but that’s next week’s blog.
John is a violinist in a local community orchestra and has been noticing tinnitus and a feeling of fullness in his left ear for about a year. His family physician has been giving him decongestants to treat the fullness.
Audiometric testing indicated a “typical” notched audiogram with the notches centered at 6000 Hz. Consistent with many violinists (viola players and drummers) John’s left ear is about 25 dB worse than his right ear at 6000 Hz.
Audiometric asymmetries are found in many forms of noise exposure. We see them in riveters and rifle shooters (with the opposite ear of one’s handedness having greater hearing loss). In cases such as this, the noise source of the rivet or gun blast is nearer one ear than another. We also see audiometric asymmetries with some musical instruments where again, the music generator is nearer one ear than the other. Violinists and viola players hold their noise generators near their left ear (except for one Canadian amazing east coast violinist named Ashley MacIsaac who plays his violin “backwards”). And drummers have their high hat on their left side and it is the high hat cymbal that tends to be the most damaging element of a drum kit.
There are two reasons why most forms of noise exposure result in symmetrical hearing loss: (1) Industrial noise is predominantly lower frequency which have long wavelengths- the noise does not “see” the head as an obstruction and despite being generate on the right side of a worker, and it may be of almost identical sound level by the time it reaches the other ear… there is no head shadow for low frequency sounds. (2) Industrial workers live their occupational lives in highly reverberant environments so a sound source emanating from the left side may be almost as intense by the time it reflects off hard floors and machinery and reaches the right side. Exposure tends to be symmetrical regardless of the origin of the low frequency sound source.
Neither of these two reasons rear their heads when it comes to a musical venue. Musicians play in relatively good sound treated environments which do not have excessive reverberation. In addition, music may have low frequency fundamental energy, but also significant higher frequency fundamental and harmonic energy. Because the wavelength of music can be shorter than industrial noise, there is some head shadow (and body baffle) effects such that music generated at the left ear (e.g. a violin) may have significantly lower sound levels (about 4 dB) when measured at the right ear. Because of the low reverberation in the musical venue, like Los Vegas, what is generated on the left side stays on the left side (or something like that is about Los Vegas… what happens in Los Vegas stays in…?)
So, John’s slight left ear audiometric asymmetry at 6000 Hz is “explained” by his poor choice of musical instrument- only the clarinet is a perfect musical instrument (but then again, I may be biased!)
However, for the sake of maintaining a good audiological standard, whenever there is an asymmetry, he was sent for an MRI. (In larger cities in Canada it seems that it takes a shorter time to obtain an MRI than an ABR) and the MRI revealed the existence of a small acoustic schwannoma on the left side. John is now being followed by an excellent otoneurologist who was just as surprised by me about the result.
An explained result does not necessarily mean that it is the only explanation and efforts should still be made to investigate all possible pathology.