What you are PLAYING is an octave, 1-4 are the same note, say C on a C diatonic harmonica. What you are HEARING (the accordian) is the octave “bleating” which indicates to me that your harmonica is somewhat out of tune. If you are playing a Special 20: Compromised Tuning, you are out of tune as the root notes (1, 4, 7, and 10 blow) are tuned at 0 cents on a chromatic tuner. If you tongue block any two holes on the blow say 3-4 on a c harp it too will give you an octave, E on a C harp, and so on. A lee Oscar or similarily tuned harmonica (Equal Temperment) should not bleat on either the blow or draw as all the notes are tuned to 0 cents. The “Tremelo” harmonica is designed with 2 reeds in each hole chamber, one reed (the short one) is tuned a half step higher to give that bleating tremelo effect. A compromise tuned Special20 has the 3rds and 7ths at -8 cents flat to “compromise” for better sounding chords, although many players beginner and intermediate alike cannot hear the difference between a equal tempered harp and a compromised “just intonated” harp. I too liked the accordian sound of a tongue blocked octave, you can also play tongue blocked draw octaves on holes 1 and 4, holes 3 and 7, holes 4 and 8, holes 5 and 9, and holes 6 and 10. For more on Equal Terperment, and Just Intonation visit www.patmissin.com.