The term 'Muted Trumpet Sounds' refers to a type of sound produced by a trumpet when the player uses a mute. This is done by inserting a device into the bell of the instrument, which alters the sound and creates a softer, more mellow tone. The crossword solution for this term is WAHS, which stands for 'Wah-wah mute'. This type of mute is used to create a vibrato effect, which is a wavering sound that is often used in jazz music.