The sudden and unexpected death of Soundgarden and Audioslave frontman Chris Cornell has stunned both his fans and many in the music scene, prompting plenty of tributes from many of the greats in music. Here’s a look at just some of the reasons the music world is mourning the loss of Cornell.

His impact on music - Cornell’s band Soundgarden was arguably one of the key architects of the late 1980s Seattle grunge scene. Formed in 1984, the band not only paved the way for other underground music acts, but also achieved huge commercial success of their own in the early 1990s. Soundgarden was one of the first bands to sign with Subpop, a record label that later took on Nirvana and Mudhoney, and was the first of the Seattle bands to sign to a major label, A&M, in 1989, going on to sell more than 12 million albums.

That voice - Chris Cornell’s powerful, gravelly voice, with a range that spanned nearly four octaves, has been called one of the best ever in rock music. Often beginning songs in a low baritone, Cornell could switch into falsetto or belt in out in a trademark rough near-scream.

“Chris Cornell will go down as one of the best singers of all time, period. He’s right up there with Roger Daltrey and Robert Plant,” Music journalist Alan Cross told CTV News Channel Thursday. “He could wail with the best of them, but if anyone went to one of his solo acoustic shows, they hear how he could be just as delicate.”

As Cornell aged, there was less of the vocal acrobatics, but his voice remained distinctive and captivating. In 2011, Rolling Stone readers ranked Cornell No. 9 on its list of the best lead singers of all time, while MTV ranked him 12th in a list of the "22 Greatest Voices in Music."

Here are two examples that showcase his range:

His prolific work - Over his 30-year career, Cornell took few breaks from writing and performing, sometimes working on several projects at once to dabble in soul, R&B, and metal music. With Soundgarden, he collaborated with former members of Mother Love Bone, to create the one-album band Temple of the Dog. He released five albums of solo work, one with Soundgarden and another during his time with Audioslave.

In his later years, he contributed to several movie soundtracks, writing and performing the theme song for the James Bond flick, “Casino Royale,” the end title song for The Avengers, and earning a Golden Globe nomination for his song “The Keeper” from the 2011 action film, Machine Gun Preacher.

He still sold out venues - As testament to his enduring appeal, last year, Cornell completed a sold-out solo acoustic tour throughout Europe and North American, called Higher Truth. When he died Wednesday, he was in the middle of a huge North American tour with Soundgarden that was also selling out venues and that was due to wrap up next week.

His philanthropy - In 2012, Cornell founded the Chris And Vicky Cornell Foundation with his wife to raise funds and mobilize support for children around the world facing homelessness, poverty and abuse. Just last month, he and his wife visited an Afghan refugee camp in Greece to offer the help of his charity, and last year, he told Alternative Nation his aim was to give back.

“I was lucky enough to be in the right place at the right time to make a career doing something I love,” he said. “Not every kid gets those opportunities. I’m in a fortunate position to use music to support important causes that help foster change.”