I couldn't believe how calm their singing made me feel. It kind of just drowned out everything else, I haven't felt that peaceful outside of a silence chamber.— An Ecai diplomat
An unusual choir
In the northern islands of Haqhor there is a musical tradition which has been around for thousands of years. It is a form of singing performed by large choirs. The Qhigu have a very deep and resonating vocal range, which is put to full effecet by these choirs. They produce a low thrumming vibrating sound which they can subtly vary the pitch of by changing the shape of their mouths and throats.
Origins
When settlers landed on the islands things went very well at first. The islands were rich in flora and fauna, the soil was fertile and ripe for planting, and the seas produced their own bountiful harvests. There was the particular issue of swarming insects though, They appeared every evening, in the hour between the sun setting and the second moon rising. They weren't particularly dangerous, more of a nuisance, it was more the fact that they swarmed in thousands and got into everything. For an hour every day the people had to shut them selves indoors and make sure everything kept outside was also shut up tight.
One day a mother noticed that her young child had not come indoors with them during the swarm, when she went outside to get him she found him sitting on the ground, humming to himself as he was often wont to do, the startling thing was that the insects didn't seem to go within a couple of foot of the young child. After relating this incident to the rest of the settlers, the following night they experimented by all humming as the child did, the insects didn't come within several feet of the singers. So it was that every night thereafter, groups of Qhigu would position themselves around the settlement and hum. Over time the singers developed the humming into specific songs, and the choirs became a tradition of the settlement. it kept going long after other methods had been developed to keep away the insects.
A Cultural Export
Once travel and communications between planets became more developed, the tradition spread and became a bit of a musical sensation. When the Ecai first encountered the Qhigu they were treated to a performance from one these choirs, the effect on them was quite astonishing. The thrumming tones had an unusually calming effect upon the Ecai, it dulled their empathic senses and made them feel peaceful.
Upon realising that this form of entertainment was worth something to the Ecai, the Qhigu immediately realised that profit could be made. Haqhor choirs are much sought after by Ecai and a group of singers can make good money either hiring themselves out for events or even going to work on a more permanent basis at settlements with large Ecai populations.
I love the ideas of the humming being used to keep the insect away and then used as a kind of calming treatment :D