Diplacusis Piano
The diplacusis piano is an instrument that recreates exactly what I hear when a normal piano is played. It is necessarily a digital instrument: there is no way this could be done using traditional technologies. I have been greatly helped by my GNResound Linx Quattro hearing aids and by my friend, the composer and Professor Craig Vear, who provided not just technical fluency in the studio and an otologically "normal" pair of ears, but also the ability to describe each sound to me as it emerged from this new instrument.
I decided to start with a piano simply because that is the instrument I used to play back in the days when I regularly made music. Piano sounds also have a pleasing decay which I instinctively felt would work well with this phenomenon. Nobody wants to listen to sustained diplacusis!
Constructing and composing for this instrument has been daunting and has taken me many months of struggle to figure out. It was like working in a hall of endlessly reflecting mirrors. I would listen to my diplacusis with my diplacusis? it was very uncomfortable and very tiring.
Building the instrument
First we created middle C (C4) using Bosendorfer samples. Craig's ears were able to hear the interesting journey the difference tones take as the edited and filtered sample unfolds (mine could only hear the first few seconds of each sound). This was the first clue about the creative possibilities that would subsequently emerge.
We matched the extent of my hearing loss in the right channel, in particular, and panned the stereo channels hard left and hard right. We introduced some filters to take out the lower frequencies as appropriate (it gets much more extreme in the lower registers) and some high ones too, using my audiogram as a guide. Finally, we detuned the samples. In most cases this was an adjustment only to the right channel, but sometimes it also entailed adjusting the left.
I had already decided that none of the sounds will rise above piano (i.e. soft). This is because hyperacusis (increased sound sensitivity) also means that I find any loud sounds distressing. Having tried to play a conventional piano recently, I realised that the mechanical sound of hammers hitting strings is too painful for me, regardless of the diplacusis. So this would have to be a soft and gentle instrument.
To get an idea what this sounds like, and see Craig working with me in the studio, view this detailed technical description.
The final step in the building process was to create an instrument in Logic (my sequencer of choice) using the ESX24 sampler. This maps the various samples across the whole instrument. In the range that I had specified using my singing method, we made individual samples for each note. In the other ranges we transposed samples up or down across a minor 3rd.
Composing for the diplacusis piano
The problem with composing for the resulting instrument is twofold: firstly, because of my hearing loss I cannot hear the (quiet) sounds it produces very well; secondly, what I do hear I hear with diplacusis, so diplacusis on diplacusis!
How then to compose for this instrument, given that I have only a poor idea of what a person with normal hearing would hear? My solution is to develop a visual language based on the spectrograms of each note. I have been steadily learning about the character of each spectrogram as I go.
I began with static spectrograms and learned the characteristics of each note. I then used rolling spectrograms in 2D and 3D, which may be seen in the movies, to understand how the notes evolved over time and how they could combine with one another.
Two types of visual compositon emerged from this porcess. In the first, I would try to connect the overtones of each sound in ways which looked logical or analytical. The ten improvisations are good examples of this, where I am working with what I already know about the spectrums to chain them together in interesting ways. The other approach was to treat the spectrograms themselves as evocative of the character of the music. Those pieces that have more poetic titles are good examples of this.