From Nookipedia, the Animal Crossing wiki
Gyroids (埴輪, Haniwa) are furniture items in the Animal Crossing series, primarily used as furniture inside the player's house. They are not to be confused with the Gyroid that appears outside the house in Animal Crossing. They can be found buried in the ground, like fossils, but only after rainy days.
Each and every Gyroid is unique in its own way: the way it sounds, how fast the tempo is, and pitch all depend on the size of the Gyroid and which family it belongs to. If one of K.K. Slider's songs is played on a stereo, the Gyroid will match the tempo of the song so that they synchronize. The name "Gyroid" likely originates from the word "gyrate," meaning to spin, referencing the motion that gyroids make.
In Animal Crossing: New Leaf, more Gyroids appear buried in the ground after it rains for a long time. Lazy villagers comment on this saying that they must like the rain.
Eight Gyroids may be active at one time in a room before one of them automatically turns off, although in Wild World, only four may be active at any given time.
Note: Not all Gyroid families have all the sizes of Gyroids, and a few do not have a neutral size. There are 127 Gyroids in Animal Crossing,Animal Crossing: Wild World and Animal Crossing: City Folk. In Animal Crossing: New Leaf, there are 131 Gyroids.
 In Animal Crossing (GCN),WW and CF
 Alloid Family
These Gyroids make a sound similar to a steel drum.
 Bovoid Family
These Gyroids make a mooing noise, hence the "Bovoid" name.
 Bowtoid Family
Bowtoids wear bow ties. They make a fast, repetitive sound and dance.
 Buzzoid Family
Buzzoids make a buzzing noise.
 Clankoid Family
They sound like pots and pans banging. They appear to look like garbage cans.
 Croakoid Family
They croak like a frog.
 Dekkoid Family
These Gyroids sound a little bit like they are saying "Dekkai."
 Dingloid Family
These Gyroids, as their name suggests, make bell sounds. The Wee Dingloid is the only "Wee" Gyroid and is very similar to the Mini Dingloid.
 Dinkoid Family
The Dinkoids are a lot like Sputnoids.
 Drilloid Family
These make a drilling noise.
 Droploid Family
The Droploid makes a "plop, plop, plop" sound, like water falling.
 Echoid Family
They make an echoing noise.
 Fizzoid Family
These sound like the fizz of opening a pop bottle.
 Freakoid Family
These sound like crying babies.
 Gargloid Family
These make a sound like a man gargling water.
 Gongoid Family
These sound like a gong.
 Harmonoid Family
The Harmonoids make a sound like a Steam Calliope.
 Howloid Family
Howloids make a screeching noise like an owl.
 Lamentoid Family
Lamentoids are based off of the word "lament," and make rattling sounds when they spin. They do not have the same facial features as most Gyroids do.
 Lullaboid Family
 Metatoid Family
These make a metalic rattling sound.
 Nebuloid Family
Nebuloids sound like a vibrating beep.
 Oboid Family
Oboids sound like an oboe.
 Oombloid Family
The Oombloids make an "oom" sound.
 Percoloid Family
Percoloids sound like hitting a hollow tree trunk.
They sound like tiny wooden bells.
 Poltergoid Family
These make a scary shriek.
 Puffoid Family
These Gyroids sound like a person blowing on a pan flute.
 Quazoid Family
These make futuristic-sounding noises.
 Rhythmoid Family
They are in tune with the music.
 Rustoid Family
These make a clanking noise, like rusted metal.
 Sproid Family
Sproids make a noise similar to that of a spring.
 Sputnoid Family
Their names derive from the satellite Sputnik and make the noise of a spacecraft drifting through space. These Gyroids have metallic bodies and large, colorful panels.
 Squelchoid Family
They sound like Velcro.
 Strumboid Family
These Gyroids make sounds similar to a guitar. The name comes from the strum, a basic guitar technique.
 Timpanoid Family
Timpanoids sound like timpani drums.
 Tootoid Family
Tootoids make a noise that sounds like flatulence.
 Warbloid Family
Warbloids make a sound like a woman gargling water.
 Brewstoid Family