Here is an attempt to model the way musical pitches sound to me nowadays. I hear two notes in place of the usual one. This phenomenon is called diplacusis. It is one of the many consequences of the hearing loss resulting from my Ménière’s Disease.
In future posts I will explore how I perceive timbre, localisation, idiom, etc. The changes are quite profound.
Digital technology is enabling us to do something that was previously impossible: to present to people with ‘normal’ hearing how someone like myself with hearing loss actually hears. It reminds me of that Marcel Duchamp note in the Box of 1914: “One can look at seeing, but one cannot hear hearing”. We are now in a position where this is no longer true!
The following experiment is quite raw, but nevertheless gives a pretty good idea of how the diplacusis works, at least within my singing range. Bear in mind that the hearing loss is severe in my right ear and mild in my left. The experiment ignores tinnitus, which also intrudes.
First I played a piano note at a given frequency (rounded to a whole number). I checked with a fine pitch meter that the tuning was correct before proceeding.
I then blocked my right ear and sang the note I heard, checking against the pitch meter. The left ear (my ‘good’ ear) gives generally very accurate pitch, with a few slight deviations towards the lower and upper ends of my singing range.
I then blocked my left ear and performed the same exercise using my right. The following chart shows the pitches, and the difference. Pitch was not the only difference: for example, the perceived amplitude was considerably softer from 138Hz downwards and fell away steadily. This is a typical hearing loss pattern in Ménière’s.
|Note||Frequency in Hz (rounded)||Left Ear difference (Hz)||Left Ear Perception (Hz)||Right Ear Perception (Hz)||Right Ear difference (Hz)|
What we can see quite clearly from this is that my diplacusis is active at all frequencies, but also variable. For some pitches, it is more than a semitone! For others, rather less. I hear these two pitches combined, with the out-of-tune one being softer than the in-tune.
What does this sound like? Here is my attempt to emulate this using appropriately detuned piano sounds. The ‘in tune’ note is louder than the ‘out of tune’ note, to reflect the hearing loss. The combination is pretty accurate, though, and by listening to this with by bad ear blocked I can get a better idea of what a normally hearing person would hear. There is a scale first, then the Bach Prelude No. 1:
I then tried the right ear only wearing my new GNResound hearing aid. What is fascinating is that this does not remove the diplacusis, but it does reduce it and. strangely, makes it into a smooth deviation, getting larger as the pitch descends.
I’m not entirely sure what to make of all this, but it is interesting!