Possible Clues:

• By the sound of it, the highway to tell the stream to be quiet
• High and piercing
• Quiet! The brook sound high
• High pitched
• High-pitched and penetrating
• High in an annoying way
• Like many whistles
• Tell the stream to be quiet when it's high, by the sound of it
• Of voice, highl-pitched and loud
• Like the sound of a teakettle