Duncan Schiedt, in his book The Jazz State of Indiana, says that Emil started as a child pianist in the pit of the Lyric Theater, and that he once sat in as the leader of his older brother’s combo at the Granalba Cafe at the corner of Massachusetts and Ohio streets.

On November 9, 1914, he married Helen Thomas in Marion County, Indiana, giving his age as 22, although he was only 18. The WW1 draft lists Emil as a musician at the Majestic Theatre in Indianapolis, and being medium height of slender build with brown eyes and hair. He claimed exemption on the grounds of being sole supporter of his wife and two children.

The 1920 US Census shows him living in Indianapolis and working as a musician (piano). That same year, he was the defendant in a rather amusing court case, in which the neighbouring millinery establishment complained that the 'sounds issuing from the shop disturb customers in the Myer store and prevent them from concentrating on the business of buying hats, underwear, etc.' 

"It hurts our business," explained Mr. Myer in reference to the suit. "So much noise hurts our business. They come here to buy a blouse, say. and they try to buy a blouse, but there's such a noise they can't concentrate."
Isadore Seidel, of the music concern, says he would like to know how he can run his business on a soundless basis. He says the order of the court forbids him to operate the player-piano, the piece de resistance of the shop, unless a customer has asked for some special selection or he is convinced the visitor is a prospective buyer.
"How am I to know whether a customer is a customer or not?" inquired Mr. Seidel, as he stared rather blankly at the store whence had come his trouble. "How can I sell player-piano rolls and talking machine records if I can't play them? How can I?"
The judge who issued the injunction order said that his ruling would not interfere with the music company's business as he only ordered that no noise be made that was not in the bona fide conducting of the business. The complainant had asked that the defendant be restrained from playing player-pianos in its rooms.

Emil's Vocalstyle performances seem to date from around 1919-1922. At least one of the rolls was recorded as a duet with his Isidore, crediting "Seidel Brothers" as the performers. After making rolls for Vocalstyle, Emil also played in orchestra pit bands in New York City. On his return to Indianapolis, he joined the house band at the Apollo Theatre and by 1925 had become its leader. He also owned and operated various music stores in Indianapolis throughout the 1920s.

The Emil Seidel Apollo Theatre Orchestra would later achieve a form of immortality, when Hoagy Carmichael approached Seidel to make the first record of his new composition, 'Star Dust'. On October 31, 1927, despite the lack of an orchestration, Seidel and his brilliant musicians worked from Carmichael's humming of each part to the musicians in a quiet back alley! The resulting record, produced at 5am after an all night drive across Indiana to the Richmond piano factory, is still regarded as an important part of musical history.

Seidel's later recordings, credited to 'Emil Seidel And His Orchestra', are described by Rick Kennedy in his 'Jelly Roll, Bix and Hoagy: Gennett Studios and the Birth of Recorded Jazz' as "crisp and highly professional".

Seidel’s orchestra recorded a dozen more songs through early 1928 at Gennett; later that year, he went back to New York, where he became renowned as a radio accompanist. The 1930 US Census records him as living at 790 Riverside Drive, Manhattan, New York with wife Helen and children Gretchen and Thomas and working as a theatre musician.

When interviewed by Rudi Blesh for his seminal book 'They All Played Ragtime', Seidel was concerned that Scott Joplin and James Scott received their due credit as "the regional originators", and described himself as "still an Ozark hillbilly at heart.. (who has) great reverence for the creators of ragtime".

Seidel died in September 1950.