muteSound ({ getters }, id) {
      const sound = getters.getSoundById(id)
      if (!sound) {
        throw new Error(`Sound ID does not exist: ${id}`)
      }

      sound.mute(true)
      return id
    }
Mutes a sound regardless of current mute state.  Maintains volume
settings on sound.

@param id {string} song ID to mute

@return sound ID that was muted

@throws {Error} when invalid sound ID specified