trebling

adjective

1. threefold; triple
2. 1. of or for the highest part in musical harmony
   2. playing or singing this part
3. high-pitched or shrill

noun

1. the highest part in musical harmony; soprano
2. a singer or instrument that takes this part
3. a high-pitched voice or sound
4. the higher part of the audio-frequency band in sound reproduction

transitive verb, intransitive verb trebled, trebling