Howling Stone

Making their first appearance in Twilight Princess, the Howling Stones are stones that enable Link to learn new Hidden Skills. They bear the Sheikah Eye Symbol, so in that aspect they are very similar in appearance to the Gossip Stones.

Function
When standing next to them, Link will be able to hear the wind blowing a tune. In wolf form, Link must howl the tune next to the stone; afterward, he will be transported to another landscape, where he will then have to howl the tune again. This time, however, the Golden Wolf will howl with him. Notably, the tunes howled using the howling stones are songs from Ocarina of Time and Majora's Mask. Along with a song from The Wind Waker and Twilight Princess. The locations of the stones are shown in the list below.

There is no Howling Stone for the first meeting with the golden wolf, since Link will encounter it on the way to the Forest Temple. There is also an additional Howling Stone, which is just required to enter the Sacred Grove, and will not let Link learn a new skill.

Locations

 * Howling Stone 1: Death Mountain (Song of Healing from Majora's Mask)
 * Howling Stone 2: Upper Zora's River (Requiem of Spirit from Ocarina of Time)
 * Howling Stone 3: Sacred Grove (Prelude of Light from Ocarina of Time)
 * Howling Stone 4: Sacred Grove (Zelda's Lullaby from Ocarina of Time) - Used to enter.
 * Howling Stone 5: Lake Hylia (Goron Lullaby from Majora's Mask)
 * Howling Stone 6: Snowpeak Trail (Ballad of Gales from The Wind Waker)
 * Howling Stone 7: Hidden Village (Original Twilight Princess composition; used variously throughout Twilight Princess such as the theme of the light spirits or when crossing Hyrule Field).

Trivia

 * The Howling Stone used to enter Sacred Grove has the Triforce symbol on it rather the eye symbol. Furthermore, the song played at the this stone is Zelda's Lullaby. This is likely a reference to Ocarina of Time, where that song is used to trigger events when a Triforce symbol is present.
 * Many fans like to refer to the final wolf song as the Ballad of Twilight, despite no confirmation of any title.
 * The Sound Stones in Spirit Tracks have the same funcion of the Howling Stones.
 * The Howling Stones all strongly resemble both the Lens of Truth, and the Shekiah symbol, this could potentially mean that the Shekiah were involved with making the stones, despite in fact that the Ballad of Gales is shown in Snowpeak.