  Acoustic metasurfaces manipulate waves with specially designed structures and
achieve properties that natural materials cannot offer. Similar surfaces work
in audio frequency range as well and lead to marvelous acoustic phenomena that
can be perceived by human ears. Being intrigued by the famous Maoshan Bugle
phenomenon, we investigate large scale metasurfaces consisting of periodic
steps of sizes comparable to the wavelength of audio frequency in both time and
space domains. We propose a theoretical method to calculate the scattered sound
field and find that periodic corrugated surfaces work as spatial filters and
the frequency selective character can only be observed at the same side as the
incident wave. Maoshan Bugle phenomenon can be well explained with the method.
Finally, we demonstrate that the proposed method can be used to design
acoustical landscapes, which transform impulsive sound into famous trumpet
solos or other melodious sound.
