Making music is not just a matter of interpretation and technique, the instrument itself makes a difference. This is especially true of piobaireachd where harmonics and mutual resonances between chanter and drones are so important. The highland bagpipe is famously cantankerous, sensitive to moisture and temperature. An instrument may by sounding sweet one day and refusing to cooperate the next. A musician will often know that they have to play for a certain period of time for their bagpipe to settle. This knowledge quickly devolves into voodoo when trying to predict what is necessary to do in order that it will be in tip top shape, say, as quickly as possible 45 minutes from now after a 10 minute break and taking it into a different room where it is three degrees warmer.
Attempts to do anything substantially better than using rules of thumb and wisdom of unknown origin are often met with the objection that, “there are too many variables to possibly understand or predict what’s going to happen”. Perhaps it is so. But let us start by measuring what we can conveniently measure.
The plot at right shows a test session playing in relatively controlled conditions, indoors on a pipe with cane reeds and a synthetic zippered bag. It shows about five minutes of rest, where the humidity sits at about 20%, a half hour of mostly continuous playing, and fifteen minutes of airing out, with the bag open. The humidity stabilises (saturates) after about 20 minutes of playing. Perhaps not coincidentally it is at this time that the sound stabilises as well, with the reeds no longer sharpening, and producing a solid, consistent sound.
The pipe uses a moisture control system that had its desiccant beads replaced with a simple data logger, shown below, that measures the humidity and temperature of the air on its way out of the pipe. A simple bottle trap with absorbent material was used.
The data logger is based on a an Arduino Nano clone and a DHT11 sensor. This is not an especially good sensor, in particular an improved version of the data logger that can also measure pressure is in the works when parts arrive. But it was what we had spare around the Edinburgh Hacklab, and as we can see above, is already enough to get some idea of the relationship between the moisture levels inside the bag and “settling” of the instrument.
The software that it runs is free, albeit very quickly and roughly put together. It records 30 second average measurements for up to about three hours and stores them on its internal flash storage. They can then be read out by a computer over USB. Another improvement might be low-energy bluetooth transmission for to see the measurements in real time on a smart telephone or tablet computer.