diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -90,3 +90,8 @@
 
 * Ninth version. Changed the module structure to four modules. Added new functions in the DobutokO.Sound.Functional module to filter possible beats. Changed some
 exports for DobutokO.Sound module.
+
+## 0.9.1.0 -- 2020-03-14
+
+* Ninth version revised A. Removed two functions from DobutokO.Sound.Functional module because of their inefficient work that leads to very long
+(possibly infinitely) computation. 
diff --git a/DobutokO/Sound/Functional.hs b/DobutokO/Sound/Functional.hs
--- a/DobutokO/Sound/Functional.hs
+++ b/DobutokO/Sound/Functional.hs
@@ -13,8 +13,6 @@
 module DobutokO.Sound.Functional (
   -- * Use additional function as a parameter
   oberSoXSynth2FDN
-  , oberSoXSynth2FDN_B
-  , oberSoXSynth2FDN_B2
 ) where
 
 import Numeric
@@ -40,7 +38,7 @@
  | otherwise = do
     let note0 = closestNote (if x /= 0.0 then abs x else V.unsafeIndex notes 0)
         note1 = dNote (V.unsafeIndex (intervalsFromString zs) 0) note0
-        g0    = V.fromList . nubBy (\(x1,_) (x2,_) -> x1 == x2) . sortBy (\(x1,_) (x2,_) -> compare x1 x2) . V.toList . V.map (\(noteX, amplX) ->
+        g0    = V.fromList . nubBy (\(x1,_) (x2,_) -> x1 == x2) . V.toList . V.map (\(noteX, amplX) ->
            if noteX <= 0.0 then (fromIntegral 2 * note0, abs (amplX - (fromIntegral . truncate $ amplX))) else (closestNote noteX,
              abs (amplX - (fromIntegral . truncate $ amplX)))) . f
         g k   = V.takeWhile (\w -> compare (fst w) (V.unsafeIndex notes 107) /= GT && compare (snd w) 0.001 == GT) .
@@ -67,86 +65,3 @@
     let paths = sort . filter (isPrefixOf "test") $ paths0
     _ <- readProcessWithExitCode (fromJust (showE "sox")) (["--combine", "mix"] ++ paths ++ ["result.wav","vol","0.3"]) ""
     mapM_ removeFile paths
-
--- | Similar to 'oberSoXSynth2FDN' but you specify additional third 'Double' argument from range [0.1..10.0] that is a difference between neighbour frequencies
--- in Hz that is used to filter the frequencies that can cause beating because of close frequencies. If it is not in the range, then the function tries to
--- reposition its value to the range. 
---
--- Be aware that the result can be rather unpredictable (the program can even obtain segmentation fault) for not very suitable function.
--- But for a lot of functions this works well.
-oberSoXSynth2FDN_B :: (Double -> V.Vector (Double, Double)) -> Double -> Double -> Double -> String -> IO ()
-oberSoXSynth2FDN_B f x y limB zs
- | V.null . convertToProperUkrainian $ zs = oberSoXSynth x
- | otherwise = do
-    let limA0 = abs ((limB / fromIntegral 10) - (fromIntegral . truncate $ (limB / fromIntegral 10))) * fromIntegral 10
-        limA  = if compare limA 0.1 == LT then 0.1 else limA
-        note0 = closestNote (if x /= 0.0 then abs x else V.unsafeIndex notes 0)
-        note1 = dNote (V.unsafeIndex (intervalsFromString zs) 0) note0
-        g0    = V.fromList . nubBy (\(x1,_) (x2,_) -> x1 == x2) . sortBy (\(x1,_) (x2,_) -> compare x1 x2) . V.toList . V.map (\(noteX, amplX) ->
-           if noteX <= 0.0 then (fromIntegral 2 * note0, abs (amplX - (fromIntegral . truncate $ amplX))) else (closestNote noteX,
-             abs (amplX - (fromIntegral . truncate $ amplX)))) . f
-        g k   = V.takeWhile (\w -> compare (fst w) (V.unsafeIndex notes 107) /= GT && compare (snd w) 0.001 == GT) . V.fromList . 
-                   nubBy (\(x1,_) (x2,_) -> compare (abs (x1 - x2)) limA /= GT) . V.toList . V.imap (\i (noteY,z0) -> (fromIntegral (i + 1) * (fst . V.unsafeIndex (g0 k) $
-                      0), z0)) . g0 $ k 
-        v0    = g note0
-        v1    = if isNothing note1 then V.empty
-                else g . fromJust $ note1
-        oberSoXSynthHelp vec = V.imapM_ (\i (noteN, amplN) -> readProcessWithExitCode (fromJust (showE "sox"))
-          ["-r22050", "-n", "test0" ++ show (i + 2) ++ ".wav", "synth", showFFloat (Just 4) y $ show 0,"sine", showFFloat (Just 4) noteN $ show 0,
-            "vol", showFFloat (Just 4) amplN $ show 0] "") vec
-        oberSoXSynthHelp2 vec = V.imapM_ (\i (noteN, amplN) -> readProcessWithExitCode (fromJust (showE "sox"))
-          ["-r22050", "-n", "test1" ++ show (i + 2) ++ ".wav", "synth", showFFloat (Just 4) y $ show 0,"sine", showFFloat (Just 4) noteN $ show 0,
-            "vol", showFFloat (Just 4) amplN $ show 0] "") vec
-    _ <- readProcessWithExitCode (fromJust (showE "sox")) ["-r22050", "-n", "testA.wav", "synth", showFFloat (Just 4) y $ show 0,"sine",
-       showFFloat (Just 4) note0 $ show 0] ""
-    if isNothing note1 then do
-      oberSoXSynthHelp v0
-    else do 
-      _ <- readProcessWithExitCode (fromJust (showE "sox")) ["-r22050", "-n", "testB.wav", "synth", showFFloat (Just 4) y $ show 0,"sine",
-         showFFloat (Just 4) (fromJust note1) $ show 0] ""
-      oberSoXSynthHelp v0
-      oberSoXSynthHelp2 v1
-    paths0 <- listDirectory "."
-    let paths = sort . filter (isPrefixOf "test") $ paths0
-    _ <- readProcessWithExitCode (fromJust (showE "sox")) (["--combine", "mix"] ++ paths ++ ["result.wav","vol","0.3"]) ""
-    mapM_ removeFile paths    
-   
--- | Similar to 'oberSoXSynth2FDN_B' but the function does not try to make real obertones, so the class of functions that it can use may be broader. 
---
--- Be aware that the result can be rather unpredictable (the program can even obtain segmentation fault) for not very suitable function.
--- But for a lot of functions this works well.
-oberSoXSynth2FDN_B2 :: (Double -> V.Vector (Double, Double)) -> Double -> Double -> Double -> String -> IO ()
-oberSoXSynth2FDN_B2 f x y limB zs
- | V.null . convertToProperUkrainian $ zs = oberSoXSynth x
- | otherwise = do
-    let limA0 = abs ((limB / fromIntegral 10) - (fromIntegral . truncate $ (limB / fromIntegral 10))) * fromIntegral 10
-        limA  = if compare limA 0.1 == LT then 0.1 else limA
-        note0 = closestNote (if x /= 0.0 then abs x else V.unsafeIndex notes 0)
-        note1 = dNote (V.unsafeIndex (intervalsFromString zs) 0) note0
-        g0    = V.fromList . nubBy (\(x1,_) (x2,_) -> x1 == x2) . sortBy (\(x1,_) (x2,_) -> compare x1 x2) . V.toList . V.map (\(noteX, amplX) ->
-           if noteX <= 0.0 then (fromIntegral 2 * note0, abs (amplX - (fromIntegral . truncate $ amplX))) else (closestNote noteX,
-             abs (amplX - (fromIntegral . truncate $ amplX)))) . f
-        g k   = V.takeWhile (\w -> compare (fst w) (V.unsafeIndex notes 107) /= GT && compare (snd w) 0.001 == GT) . V.fromList . 
-                   nubBy (\(x1,_) (x2,_) -> compare (abs (x1 - x2)) limA /= GT) . V.toList . g0 $ k 
-        v0    = g note0
-        v1    = if isNothing note1 then V.empty
-                else g . fromJust $ note1
-        oberSoXSynthHelp vec = V.imapM_ (\i (noteN, amplN) -> readProcessWithExitCode (fromJust (showE "sox"))
-          ["-r22050", "-n", "test0" ++ show (i + 2) ++ ".wav", "synth", showFFloat (Just 4) y $ show 0,"sine", showFFloat (Just 4) noteN $ show 0,
-            "vol", showFFloat (Just 4) amplN $ show 0] "") vec
-        oberSoXSynthHelp2 vec = V.imapM_ (\i (noteN, amplN) -> readProcessWithExitCode (fromJust (showE "sox"))
-          ["-r22050", "-n", "test1" ++ show (i + 2) ++ ".wav", "synth", showFFloat (Just 4) y $ show 0,"sine", showFFloat (Just 4) noteN $ show 0,
-            "vol", showFFloat (Just 4) amplN $ show 0] "") vec
-    _ <- readProcessWithExitCode (fromJust (showE "sox")) ["-r22050", "-n", "testA.wav", "synth", showFFloat (Just 4) y $ show 0,"sine",
-       showFFloat (Just 4) note0 $ show 0] ""
-    if isNothing note1 then do
-      oberSoXSynthHelp v0
-    else do 
-      _ <- readProcessWithExitCode (fromJust (showE "sox")) ["-r22050", "-n", "testB.wav", "synth", showFFloat (Just 4) y $ show 0,"sine",
-         showFFloat (Just 4) (fromJust note1) $ show 0] ""
-      oberSoXSynthHelp v0
-      oberSoXSynthHelp2 v1
-    paths0 <- listDirectory "."
-    let paths = sort . filter (isPrefixOf "test") $ paths0
-    _ <- readProcessWithExitCode (fromJust (showE "sox")) (["--combine", "mix"] ++ paths ++ ["result.wav","vol","0.3"]) ""
-    mapM_ removeFile paths    
diff --git a/dobutokO2.cabal b/dobutokO2.cabal
--- a/dobutokO2.cabal
+++ b/dobutokO2.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                dobutokO2
-version:             0.9.0.0
+version:             0.9.1.0
 synopsis:            A program and a library to create experimental music from a mono audio and a Ukrainian text
 description:         It can also create a timbre for the notes
 homepage:            https://hackage.haskell.org/package/dobutokO2