Voiceless

This is strange. I don't cough, have a sore throat, high temperature or show any other symptom of something being wrong - yet for some five days now I have only been able to speak at the lowest pitch and very quietly. Quietly to the point of being inaudible in the factory din, so to communicate I have to try and raise both pitch and volume; and little as I can manage that anyway, it makes my voice rasp so much that it resembles more a loud whisper than normal speech.