diff --git a/source/use_case/asr/src/Wav2LetterPreprocess.cc b/source/use_case/asr/src/Wav2LetterPreprocess.cc
index e5ac3ca..590d08a 100644
--- a/source/use_case/asr/src/Wav2LetterPreprocess.cc
+++ b/source/use_case/asr/src/Wav2LetterPreprocess.cc
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021 Arm Limited. All rights reserved.
+ * Copyright (c) 2021-2022 Arm Limited. All rights reserved.
  * SPDX-License-Identifier: Apache-2.0
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
@@ -24,37 +24,31 @@
 
 namespace arm {
 namespace app {
-namespace audio {
-namespace asr {
 
-    Preprocess::Preprocess(
-        const uint32_t  numMfccFeatures,
-        const uint32_t  windowLen,
-        const uint32_t  windowStride,
-        const uint32_t  numMfccVectors):
-            m_mfcc(numMfccFeatures, windowLen),
-            m_mfccBuf(numMfccFeatures, numMfccVectors),
-            m_delta1Buf(numMfccFeatures, numMfccVectors),
-            m_delta2Buf(numMfccFeatures, numMfccVectors),
-            m_windowLen(windowLen),
-            m_windowStride(windowStride),
+    ASRPreProcess::ASRPreProcess(TfLiteTensor* inputTensor, const uint32_t numMfccFeatures,
+            const uint32_t numFeatureFrames, const uint32_t mfccWindowLen,
+            const uint32_t mfccWindowStride
+            ):
+            m_mfcc(numMfccFeatures, mfccWindowLen),
+            m_inputTensor(inputTensor),
+            m_mfccBuf(numMfccFeatures, numFeatureFrames),
+            m_delta1Buf(numMfccFeatures, numFeatureFrames),
+            m_delta2Buf(numMfccFeatures, numFeatureFrames),
+            m_mfccWindowLen(mfccWindowLen),
+            m_mfccWindowStride(mfccWindowStride),
             m_numMfccFeats(numMfccFeatures),
-            m_numFeatVectors(numMfccVectors),
-            m_window()
+            m_numFeatureFrames(numFeatureFrames)
     {
-        if (numMfccFeatures > 0 && windowLen > 0) {
+        if (numMfccFeatures > 0 && mfccWindowLen > 0) {
             this->m_mfcc.Init();
         }
     }
 
-    bool Preprocess::Invoke(
-                const int16_t*  audioData,
-                const uint32_t  audioDataLen,
-                TfLiteTensor*   tensor)
+    bool ASRPreProcess::DoPreProcess(const void* audioData, const size_t audioDataLen)
     {
-        this->m_window = SlidingWindow<const int16_t>(
-                            audioData, audioDataLen,
-                            this->m_windowLen, this->m_windowStride);
+        this->m_mfccSlidingWindow = audio::SlidingWindow<const int16_t>(
+                static_cast<const int16_t*>(audioData), audioDataLen,
+                this->m_mfccWindowLen, this->m_mfccWindowStride);
 
         uint32_t mfccBufIdx = 0;
 
@@ -62,12 +56,12 @@
         std::fill(m_delta1Buf.begin(), m_delta1Buf.end(), 0.f);
         std::fill(m_delta2Buf.begin(), m_delta2Buf.end(), 0.f);
 
-        /* While we can slide over the window. */
-        while (this->m_window.HasNext()) {
-            const int16_t*  mfccWindow = this->m_window.Next();
+        /* While we can slide over the audio. */
+        while (this->m_mfccSlidingWindow.HasNext()) {
+            const int16_t* mfccWindow = this->m_mfccSlidingWindow.Next();
             auto mfccAudioData = std::vector<int16_t>(
                                         mfccWindow,
-                                        mfccWindow + this->m_windowLen);
+                                        mfccWindow + this->m_mfccWindowLen);
             auto mfcc = this->m_mfcc.MfccCompute(mfccAudioData);
             for (size_t i = 0; i < this->m_mfccBuf.size(0); ++i) {
                 this->m_mfccBuf(i, mfccBufIdx) = mfcc[i];
@@ -76,11 +70,11 @@
         }
 
         /* Pad MFCC if needed by adding MFCC for zeros. */
-        if (mfccBufIdx != this->m_numFeatVectors) {
-            std::vector<int16_t> zerosWindow = std::vector<int16_t>(this->m_windowLen, 0);
+        if (mfccBufIdx != this->m_numFeatureFrames) {
+            std::vector<int16_t> zerosWindow = std::vector<int16_t>(this->m_mfccWindowLen, 0);
             std::vector<float> mfccZeros = this->m_mfcc.MfccCompute(zerosWindow);
 
-            while (mfccBufIdx != this->m_numFeatVectors) {
+            while (mfccBufIdx != this->m_numFeatureFrames) {
                 memcpy(&this->m_mfccBuf(0, mfccBufIdx),
                        mfccZeros.data(), sizeof(float) * m_numMfccFeats);
                 ++mfccBufIdx;
@@ -88,39 +82,37 @@
         }
 
         /* Compute first and second order deltas from MFCCs. */
-        Preprocess::ComputeDeltas(this->m_mfccBuf,
-                            this->m_delta1Buf,
-                            this->m_delta2Buf);
+        ASRPreProcess::ComputeDeltas(this->m_mfccBuf, this->m_delta1Buf, this->m_delta2Buf);
 
-        /* Normalise. */
-        this->Normalise();
+        /* Standardize calculated features. */
+        this->Standarize();
 
         /* Quantise. */
-        QuantParams quantParams = GetTensorQuantParams(tensor);
+        QuantParams quantParams = GetTensorQuantParams(this->m_inputTensor);
 
         if (0 == quantParams.scale) {
             printf_err("Quantisation scale can't be 0\n");
             return false;
         }
 
-        switch(tensor->type) {
+        switch(this->m_inputTensor->type) {
             case kTfLiteUInt8:
                 return this->Quantise<uint8_t>(
-                        tflite::GetTensorData<uint8_t>(tensor), tensor->bytes,
+                        tflite::GetTensorData<uint8_t>(this->m_inputTensor), this->m_inputTensor->bytes,
                         quantParams.scale, quantParams.offset);
             case kTfLiteInt8:
                 return this->Quantise<int8_t>(
-                        tflite::GetTensorData<int8_t>(tensor), tensor->bytes,
+                        tflite::GetTensorData<int8_t>(this->m_inputTensor), this->m_inputTensor->bytes,
                         quantParams.scale, quantParams.offset);
             default:
                 printf_err("Unsupported tensor type %s\n",
-                    TfLiteTypeGetName(tensor->type));
+                    TfLiteTypeGetName(this->m_inputTensor->type));
         }
 
         return false;
     }
 
-    bool Preprocess::ComputeDeltas(Array2d<float>& mfcc,
+    bool ASRPreProcess::ComputeDeltas(Array2d<float>& mfcc,
                                    Array2d<float>& delta1,
                                    Array2d<float>& delta2)
     {
@@ -175,20 +167,10 @@
         return true;
     }
 
-    float Preprocess::GetMean(Array2d<float>& vec)
+    void ASRPreProcess::StandardizeVecF32(Array2d<float>& vec)
     {
-        return math::MathUtils::MeanF32(vec.begin(), vec.totalSize());
-    }
-
-    float Preprocess::GetStdDev(Array2d<float>& vec, const float mean)
-    {
-        return math::MathUtils::StdDevF32(vec.begin(), vec.totalSize(), mean);
-    }
-
-    void Preprocess::NormaliseVec(Array2d<float>& vec)
-    {
-        auto mean = Preprocess::GetMean(vec);
-        auto stddev = Preprocess::GetStdDev(vec, mean);
+        auto mean = math::MathUtils::MeanF32(vec.begin(), vec.totalSize());
+        auto stddev = math::MathUtils::StdDevF32(vec.begin(), vec.totalSize(), mean);
 
         debug("Mean: %f, Stddev: %f\n", mean, stddev);
         if (stddev == 0) {
@@ -204,14 +186,14 @@
         }
     }
 
-    void Preprocess::Normalise()
+    void ASRPreProcess::Standarize()
     {
-        Preprocess::NormaliseVec(this->m_mfccBuf);
-        Preprocess::NormaliseVec(this->m_delta1Buf);
-        Preprocess::NormaliseVec(this->m_delta2Buf);
+        ASRPreProcess::StandardizeVecF32(this->m_mfccBuf);
+        ASRPreProcess::StandardizeVecF32(this->m_delta1Buf);
+        ASRPreProcess::StandardizeVecF32(this->m_delta2Buf);
     }
 
-    float Preprocess::GetQuantElem(
+    float ASRPreProcess::GetQuantElem(
                 const float     elem,
                 const float     quantScale,
                 const int       quantOffset,
@@ -222,7 +204,5 @@
         return std::min<float>(std::max<float>(val, minVal), maxVal);
     }
 
-} /* namespace asr */
-} /* namespace audio */
 } /* namespace app */
 } /* namespace arm */
\ No newline at end of file