Is the Largs Hum spreading?

One letter writer seems to think so.

Cheryl Brind wrote to the 'News' and said: "I read your article from back in March regarding the Largs Hum. I can hear it too. 
"I moved back to Dunoon after living in Falkirk for 10 years and suddenly all I could hear at night was the hum. I tried switching everything electrical off in the house but could still hear it.

"It wasn’t until my husband I drove out to Tinabruich earlier this year that I realised I could also hear it at the view point at the top of the hill even louder than at home. I also stayed at a friends house in Innellan last week and could hear it there too but it was slightly higher pitched.
Is the hum spreading? "