For most bands, lyrics serve as the emotional conveyer belt within a song. Artists can use words to directly transmit a message to the listener.

Every once in a while a band comes along with so much talent that raw instrumentals are enough to create the whirlwind of emotions that lyrics would otherwise provide. Chicago-based instrumental rock quartet Pelican — slated to perform at Ybor’s Orpheum tonight — is one of those bands.

Simply calling Pelican a metal band would be inaccurate. Their sound is post-metal meets hard-edged rock. With four albums since 2003, that sound has continuously grown and evolved with a seemingly effortless transition.

The Windy City musicians are signed to Hydra Head Records, a primarily metal label founded by Aaron Turner of Isis, and have produced two full-length albums and two EPs on that label. Now on tour, the band is promoting its latest album, City of Echoes.

Earlier Pelican recordings have more of a doom-metal undertone, but on later albums the band has exchanged minor-chorded walls of sound for more ambient breaks and a less amplified sound. The end product is nearly flawless.

Each record has been considerably more mature and successful than the last, building the band a solid fan base around the globe.

“If I had to explain our sound I would say it’s sort of harder-edged rock,” guitarist Trevor de Brauw said. “But in truth, we are all influenced by so many genres of music, we don’t want to be classified into one specific style.”

For those wary of a band with no vocals, it is important to assess the higher level of awareness gained when listening to instrumental music. When often-superficial vocals are removed from a song it becomes easier to appreciate its musical components. The instruments themselves sing, free from the fog of lyrics.

“It’s like when you watch a classic movie — most of the emotional impact that comes out of it comes from instrumental music or from sound effects,” de Brauw said. “Words cloud your head. Instrumentals leave way more room to feel emotions. I would personally find it harder to be more emotionally convincing as a band with lyrics — the actual instrumentals, I think, is where most of the emotional impact is rendered.”

A band’s music should progress and evolve — that’s the only way to keep it fresh and interesting. This is not always an easy task for instrumental bands, but Pelican makes it seem effortless.

“With instrumental music it becomes very easy to find yourself in a rut of repetition and to just fall back on formula,” de Brauw said. “It is really important for us to evolve and for each record to be significantly different from the  last.”

He said the band’s musical evolution has been a completely conscious one. The longer they play together, the more they are in tune with each other’s intricacies and influences — thus the better it works.

Though the band avoids genre-stereotyping, it has a thematic core, which is present in the album artwork as well as the music.

Long, slow, heavy songs lead into more uplifting tunes played in major keys for a seasonal feel. Album artwork depicts clouds, mountains and oceans.

“All four of us have an immense connection to nature,” de Brauw said. “When we recognized that quality in our music, we wanted to choose an album cover to kind of go with that.”

In mainstream music, catchy hooks often eclipse more complex musicality. A bandwagon music junkie may buy an album because he or she heard one catchy song and assumed the whole album was good, which is usually not the case.

Pelican makes the kind of albums you can listen to straight through. The progressions and layers of the atmospheric music hold up under repeat listenings.

The complex qualities of instrumental music enlighten the senses and brim with emotion. In a sea of mainstream mediocrity, Pelican may have picked up where Chopin left off.

Pelican and label mates Kayo Dot and Stephen Brodsky will play tonight at the Orpheum in Ybor City. Tickets are $12 online and $14 at the door.