VoiceJam 2025 Judges

Rob Dietz

Rob Dietz is a multiple award-winning singer and vocal percussionist who has been arranging, composing, teaching, and performing contemporary a cappella music for over twenty years. Based in Los Angeles, Rob is best known for his work as an arranger and group coach for NBC’s The Sing-Off. Through his work as an arranger, Rob has had the pleasure of collaborating with some of the top talent in the vocal music world including Grammy award-winning groups Pentatonix and The Swingles, Voiceplay, Kings Return, and many more. He has been a contributing arranger for performances by world renowned artists including Smokey Robinson, Flo Rida, Sara Bareilles, Incubus, and Pat Benatar. His arrangements have been featured on several TV shows, including America’s Got Talent (NBC), To All The Boys: P.S I Still Love You (Netflix), and Pitch Slapped (Lifetime).

A native of Ithaca, NY, Rob got his start singing in high school as a member of the a cappella quintet, Ascending Height, with whom he wrote and produced the first ever album of all original music at the high school level. He graduated from Ithaca College in 2010 with a bachelor’s degree in music and an outside field in business. While at Ithaca, Rob had the honor of directing the all male-identified group, Ithacappella, with whom he twice advanced to the finals of the International Championship of Collegiate A Cappella. He was also a member of both the Ithaca College Chorus and the Ithaca College Choir -the college’s select, touring vocal ensemble.

As a performer, Rob is an award-winning vocal percussionist, and his distinctive sound has been featured on several TV shows, including FOX's Glee and The Late Late Show with James Corden. Rob was the founding vocal percussionist for both The Funx and Level, groups that gave him the opportunity to work with legendary performers including Jay Leno and Demi Lovato.  

Rob has a deep passion for a cappella education, and is a founding co-director (along with Ben Bram and Avi Kaplan) of A Cappella Academy. In addition to his work with Academy, Rob is also the director of Legacy: an auditioned, community youth a cappella group based in Los Angeles. Since the group’s inception, Legacy has performed twice at Carnegie Hall, and has won the Los Angeles A Cappella Festival’s Scholastic Competition, the Southwest semifinal round of the Varsity Vocals A Cappella Open, and the Finals of the International Championship of High School A Cappella at Lincoln Center.

Rob is a sought-after presenter and clinician who has led vocal music workshops at events such as the National A Cappella Convention and ACDA National. He has directed several honor choirs, including the inaugural Contemporary A Cappella Honor Ensembles at the Southwest ACDA regional conference, and the Pennsylvania Music Educators Association’s state-wide conference in 2024. He is the author of A Cappella 101: A Beginner’s Guide to Contemporary A Cappella Singing, published by Hal Leonard.

Alongside his work in contemporary a cappella music, Rob is an avid choral composer, with work published by Alfred Music Publishing, Hal Leonard, Heritage, and GIA Publications. In 2021 his piece “The Gift” received a jury commendation as part of the King’s Singers New Music Prize competition. His pieces continue to be performed by choirs from all over the world. Rob currently serves as the national repertoire and resources co-chair for Contemporary/Commercial music for the American Choral Directors Association (ACDA).

Tehillah Alfonso

New-Jersey-born and Nebraska-raised, Tehillah Alphonso is a Nigerian-American vocalist, pianist, music director, and GRAMMY®-nominated arranger based in Los Angeles, California. A proud Summa Cum Laude graduate of the University of Southern California, she received her B.M. in Popular Music Performance from the Thornton School of Music and was named 2020 Outstanding Graduate, becoming the first Black woman in the pop program to achieve this award. While a full-time student at USC, Tehillah served as Business Manager and Music Director of USC’s premiere a cappella group and five-time ICCA champions, the SoCal VoCals.

Her time in the VoCals has led her to perform in venues such as the Staples Center, the Rose Bowl, Carnegie Hall, and many historic theaters in Los Angeles and New York. Upon graduating, she quickly made a name for herself in the session music industry, having sung on a number of films and television shows and alongside notable artists, including Chloe Bailey, Lebo M, Billie Eilish, and Olivia Rodrigo.

Erin Hauger

Dr. Erin Hauger is a Professor at the University of Colorado, Denver, and the founder of two award-winning a cappella groups, MIX and Lark. Both groups have earned acclaim for their innovative approaches to collegiate a cappella, with a reputation for pushing boundaries. They are multiple-time champions of national competitions, recipients of numerous performance awards, and winners of several Contemporary A Cappella Recording Awards.

A passionate advocate for contemporary singing techniques, Dr. Hauger specializes in teaching singers how to belt in a healthy and sustainable way. She frequently presents on this topic and publishes research on the history of contemporary female singers. Her most recent article about Eartha Kitt can be found in the Kapralova Society Journal of Women in Music.

Jojo Otseidu (The Edge Effect)

Jojo is a Ghanaian-American bass singer, vocal percussionist, director and arranger who studied at Ohio State University. Jojo served as Music Director of Ohio State's top a cappella group, The Ohio State of Mind, for two years. In 2017, he made history by leading The Ohio State of Mind to the final round of the International Championship of Collegiate A Cappella (ICCA). This marked the first appearance ever of a group from Ohio in the final stage of the competition. Jojo was recognized as an “Outstanding Bass” at the 2017 ICCA Finals. The award is rarely given; Avi Kaplan (formerly of Pentatonix) is the only other bass singer to be recognized by the ICCA judges in this category. In 2018, he directed and led midwest super group "LUXE" to a 3rd place finish at the Aca Open in Carnegie Hall. Jojo has also been recognized with several Outstanding Arrangement Awards at Varsity Vocals competitions. He has taught classes and judged competitions at Contemporary A Cappella Society festivals ranging from LAAF to SingStrong. Previously, he performed in and arranged for internationally touring a cappella group "Backtrack" and served as a bass, vocal percussionist and assistant producer for the a cappella show 'EVOC'. He can also be heard as one of two bass singers on Disney's DCappella's self titled debut album with Walt Disney Records. These days, he sings bass with social media sensation "ReVoiced" and performs on cruises around the world in "ReVoiced" and "The Edge Effect.”

Sean Gerrity (The Edge Effect)

For over 25 years, Sean Gerrity has performed to audiences around the world. He has shared the stage with artists from Prince to Tony Bennett in venues from Carnegie Hall to the Red Carpet of the Grammys to the Las Vegas Strip. He has helped advance the acappella art form through his groups, Mosaic and The Edge Effect. He is a husband to Christina for 17 years and the father of two wonderful children, Liam and Ava.

Troy Dolendo (The Edge Effect)

Hailing from the beaches of southern California, Troy is so excited to be back as a part of Voice Jam 2025! After studying under Bobby McFerrin’s arranger, Roger Treece at UW, Troy’s A Cappella career took off. His singing, vocal percussion and arranging took him around the globe landing him in Orlando where he co-founded Mosaic and The Edge Effect. His Production and Music Direction credits include: Disney Event Group, Universal Music Group (US & Japan), Royal Caribbean International, Celebrity Cruise lines and others. His groups have taken him all over Europe, South America, The Caribbean, as well as the red carpet at The Grammys and The Academy Awards. He has shared the stage and performed with Prince, Stevie Wonder, Tony Bennet, India Arie, Mervyn Warren and others. He is uber proud to have arranged for and worked with groups like The Swingle Singers, Pentatonix, M-Pact, The HouseJacks and many others.

Troy hopes everyone here at Voice Jam has an amazing time and that they cherish every single moment!

He thanks his beautiful family for the love and support!

Danny Alan (The Edge Effect)

Danny is a founding member of the a cappella vocal group The Edge Effect and has performed as a headliner for The Walt Disney Company, Royal Caribbean Cruise Lines, Costa Cruise Lines, Crystal Cruise Lines, Marriott Hotels, KIA Motors, SunFest, Sojam, NACC and many more. A 1997 graduate of Belmont University’s  Mike Curb College of Music Business in Nashville, TN, Danny has been performing professionally since 1999. As a songwriter, he was a member of the acclaimed New York Songwriter’s Circle and was selected to take part in the BMI commercial songwriter’s workshop in 2006. Prior to founding the Edge Effect, he was a full-time member of 42Five (now Voiceplay) and was also a sub with Toxic (now Vox) Audio. Although traveling the work making music is fun, his favorite and most rewarding career is that of being husband to wife Christye and father to 13 year old twins Aidan and Ashton. Best of luck to all of the competitors!

Gabriel Hahn

Gabriel Hahn is a French-German professional musician, composer and  educator with a jazz drums diploma of the music conservatory of Munich and  a composing/arranging master’s degree of the music university of Dresden Part of the German Jazz, World Music and Experimental performance scene from the early 2000s on he became drummer and vocal/body percussionist of  the award winning Vocal Jazz legends THE NEW YORK VOICES in 2009 and  worked as background singer/percussionist for great German pop stars such  as Roger Cicero, Howard Carpendale and Max Mutzke from 2016 on. He is also part of the ‘Modern Tales’ program by the BRUSSELS VOCAL  PROJECT which released their latest album with music by John Hollenbeck for 5 singers and drums. Gabriel currently lives and works in Taiwan as a drummer, percussionist, educator and co-artistic director of the VOCAL ASIA FESTIVAL