(CNN)If you showed up late or missed the introduction, you might think she's the main attraction.
What does a guitar solo look like if you can't hear? How a sign language interpreter translates concerts
On the main stage are four middle-aged men, adorned with tattoos, tank tops and long, flowing white hair. They screech and growl, plunging their bodies back and forth.
A little off to the side is Lindsay Rothschild-Cross.
She looks like she's simply rocking out at this heavy metal concert. But she's actually performing a valuable service: interpreting each syllable, scream and solo with precision for deaf concertgoers, using American Sign Language.
Rothschild-Cross travels the country each summer to interpret at festivals and concerts, while fighting against audism, a form of ableism that discriminates against deaf people.
What goes into each concert is a mountain of research, preparation and time. What comes out is a more accessible concertgoing experience that allows everyone to partake in the joy of live summer music.
The Americans with Disabilities Act requires any place of public accommodation to provide interpreters if even one person requests one. However, many places, especially temporary festival grounds, have trouble complying.
Venues will sometimes place interpreters in mosh pits or in an inaccessible area. Rothschild-Cross emphasized the need for advocates for proper accommodation.
Occasionally, she said, the artists will not abide by the rules or will be disrespectful. Some musicians refuse to give her set lists in advance, or ask for the interpreters' spotlights to be turned off.
Concertgoers also can be rude and intolerant, she said. Rothschild-Cross noted a commonly held misconception that deaf people cannot and should not attend a live music performance.
Tara Sawyer, a deaf Californian, explained why she enjoys the concert sensation.
"You can feel the music in your body, plus get the signs and story about what the songs were about," Sawyer said. "Without an ASL interpreter, I would never bother to go."
Greg Lehr grew up listening to music but developed hearing loss later in life. Now, he said, he can hear the music but can't understand the words. Like Sawyer, he said he appreciates the community and contagious energy of going to a concert.
"Concerts are about a lot more than just the audio," Lehr said. "They're electric, with a passionate intensity, and the lights draw you in! Since deaf people are a small minority, particularly at a concert, there is also a good chance of making friends with other deaf concertgoers."
When Rothschild-Cross interprets at a concert, she doesn't just show up the day of and translate lyrics in real time. She'll spend weeks researching the artists and their repertoire, learning the back story and context for each song.
When artists won't share their set list, she makes educated guesses about what they're most likely to play and then taps into the themes and emotional motifs of each song.
Signing for rock musicians, she said she finds she's often interpreting lyrics about addiction, mental health and drug use. She said she needs to understand what the artist is feeling to do her job properly.
"I truly feel like artists, they know when an interpreter is in it for the right reasons," Rothschild-Cross said. "That's how I'm able to incorporate all of his feelings and his past struggles into that."
An interpreter is not just signing the words coming out of a singer's mouth; there are instruments, pitches and noises to convey as well.
Rothschild-Cross can sign for instrumental breaks or even beat-boxing. She'll sometimes add qualifiers -- descriptive adjectives or adverbs -- while miming an air guitar or flute solo to express the full breadth of the music.