A. R. Rahman - ABBA - Acoustics - Aerosmith - Alla Pugacheva
Backstreet Boys - Ballads - Band management - Baroque Music - Bassoon - Bee Gees - Bing Crosby - Bon Jovi
Celine Dion - Choir - Compact disk - Composition - Concert tours - Conductor
David Bowie - Dmitri Shostakovich - Duane Eddy - Duke Ellington
Edward Elgar - Elvis Presley
Felix Mendelssohn - Ferruccio Busoni - Folk Music - Frank Sinatra - Franz Liszt - Franz Schubert - Funk
George Gershwin - Georges Bizet - Giuseppe Verdi - Gospel - Grammy Awards - Guitars - Gustav Mahler
Heavy Metal Music - Hector Berlioz - Hip Hop
Igor Stravinsky - Ira Gershwin - Irving Berlin
Johann Sebastian Bach - Johann Strauss - Johannes Brahms - John Philip Sousa - Joseph Haydn
KC and the Sunshine Band
Led Zeppelin - Luciano Pavarotti - Ludwig Van Beethoven - Lute
Madonna - Marching Bands - Maurice Ravel - Medieval Music - Metropolitan Opera - Michael Jackson - Music in Films - Musicals - Musical notations - Musicians
Orchestra - Orlando Gibbons
Percusion- Peter Tchaikovsky - Phil Collins - Piano - Pipe organ - Prince - Protest Songs
Queen
Ragtime Music - Recording studios - Reggae - Richard Wagner - Roadies - Robert Schumann - Rock - Rolling Stones
Saxophone - Scott Joplin - Sergei Prokofiev - Shirley Bassey - Sitar - Ska - Synthesizer
The Beatles - The Who - Tom-Toms - Trombone
Wei Wei - Wolfgang Amadeus Mozart

Nice suggestions for persuasive speech topics about music instruments of an orchestra are:

Woodwinds: piccolo - flute - oboe - horn - clarinet - bassoon - saxophone
Brass: French horn - trumpet - trombone - tuba - euphonium
Percussion: timpani - drums - cymbals - triangle - wood block - tambourine - marimba - xylophone - glockenspiel - vibraphone
Strings: harp - violin - viola - cello

Again: these instruments, composers and artists are a good source for brainstorming interesting persuasive speech topics about music.