# How to Train MFCC Using Machine Learning Algorithms

## Introduction

Mel Frequency Cepstral Coefficients (MFCCs) is a widely used feature extraction technique for audio processing, particularly in speech recognition applications. A logarithmic compression, a filter bank, and the discrete Fourier transform (DFT) of audio signals in brief time intervals are used to create MFCCs.

You will have a thorough understanding of how to train MFCC using machine learning algorithms by the end of this article.

## What is an MFCC

MFCC stands for Mel−Frequency Cepstral Coefficients. It is a widely used feature extraction technique in audio signal processing and speech recognition. The MFCC algorithm is based on the human auditory system's perception of sound, which decomposes audio signals into frequency bands.

MFCCs are obtained by first applying the short−time Fourier transform (STFT) to a signal to obtain its spectral representation. The power spectrum of the signal is then mapped to the mel scale. The Mel scale is a non−linear frequency scale that more closely approximates the human perception of sound. The Mel scale is divided into a series of triangular overlapping frequency bands and the logarithm of the energy in each band is computed.

Finally, the discrete cosine transform (DCT) is applied to the logarithmic mel−spectrogram to obtain a set of cepstral coefficients. The resulting coefficients represent the spectral envelope of the audio signal, capturing information about its spectral content in a compact form. Typically, only the first 10−20 coefficients are used for speech recognition tasks.

## Steps to Train MFCC Using Machine Learning

Mel−frequency cepstral coefficients (MFCC) are a commonly used feature extraction technique for speech and audio signal processing. Once the MFCCs are extracted, they can be used as input features for a machine−learning algorithm. Here are some general steps to train a machine−learning algorithm using MFCCs:

• Data collection : To train a machine−learning model to recognize speech or carry out other audio−related tasks, gathering a relevant dataset of audio files is a necessary step. You might need to gather just a few hundred audio files or a few thousand, depending on the task at hand. You can create your own audio files, download publicly accessible datasets, or use both options simultaneously. Make sure your data represents the target audience and covers a wide variety of potential circumstances while gathering it.

• Preprocessing : Noise, background noise, and other abnormalities are frequently present in audio signals, which can have a detrimental effect on how well a machine−learning system performs. Therefore, prior to extracting MFCCs, the audio files must be preprocessed. Filtering out undesired noise, adjusting the audio signal's level, and eliminating silent areas are some examples of preprocessing.

• Feature Extraction : To produce MFCCs, preprocessed audio data is subjected to the Fourier transform a signal−processing technique. The audio signal is compressed into the MFCCs, which faithfully reproduce the spectrum characteristics of the sound. Each MFCC represents a particular frequency band, but the entire collection of MFCCs depicts the signal's overall spectral shape.

• Labeling : Each audio file is classified by connecting it to the relevant output or target variable. For instance, if you were teaching a speech recognition system, you would label each audio file with the pertinent transcription. Although labeling takes time, supervised machine learning algorithms require it.

• Model Selection : To get good results, it is essential to choose an appropriate machine learning algorithm. The decision−making process is dependent upon the assignment at hand because each algorithm has advantages and disadvantages. Support vector machines (SVMs) are frequently employed for binary classification problems, but neural networks are more effective for challenging problems like speech recognition.

• Training : After you've decided on a machine learning method, you can train it on the labeled dataset, with the extracted MFCCs serving as input features and the labeled data serving as output. The training process entails adjusting the algorithm's parameters to minimize the difference between the predicted and actual output. The aim is to determine the collection of parameters that delivers the best training data performance.

• Evaluation : It is essential to assess the model's performance on a separate testing set once it is trained. This evaluation helps determine the model's ability to generalize and avoid overfitting. Overfitting happens when the model is overly complex and fits the training data too well, leading to poor performance on new and unseen data.

• Iteration : After training, it is critical to assess the model's performance on a separate testing set. This assessment aids in determining the model's capacity to generalize and avoid overfitting. Overfitting occurs when a model is very complicated and overly fits the training data, resulting in poor performance on new and unknown data.

• Deployment : After you're happy with the model's performance, you can put it into production in order to generate predictions on fresh, previously unknown data. The model may be deployed as a standalone product or as part of a larger software system. To ensure that the deployed model keeps working properly, it is critical to monitor and upgrade it on a regular schedule.

## Sample Python code

Note:− code may be changed according to the dataset available.

### Example

The data set is taken from Kaggle:− https://www.kaggle.com/datasets/cracc97/features

import numpy as np
import pandas as pd

from sklearn.model_selection import train_test_split
from sklearn.preprocessing import StandardScaler
from sklearn import svm
from sklearn.metrics import accuracy_score

# Extract the MFCC features and corresponding labels
X = dataset.iloc[:, :-1]  # Assuming MFCC features are in columns 1 to n
y = dataset.iloc[:, -1]  # Assuming labels are in the first column
import pandas as pd
from sklearn.preprocessing import LabelEncoder

# Initialize the LabelEncoder
label_encoder = LabelEncoder()

# Encode the labels
y = label_encoder.fit_transform(y)

# Print the encoded DataFrame
print(y)

X.shape, y.shape
# Split the dataset into training and testing sets
X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.2, random_state=42)
# Standardize the features
scaler = StandardScaler()
X_train = scaler.fit_transform(X_train)
X_test = scaler.transform(X_test)
# Initialize and train the machine learning algorithm (e.g., Support Vector Machine)
model = svm.SVC()
model.fit(X_train, y_train)
# Predict the labels for the test set
y_pred = model.predict(X_test)
# Evaluate the accuracy of the model
accuracy = accuracy_score(y_test, y_pred)
print("Accuracy:", accuracy)


### Output

Accuracy: 0.8038598273235145


## Conclusion

In conclusion, there are a number of steps involved in training MFCC using machine learning algorithms, including data preprocessing, feature extraction, and model training. Accurate results in speech recognition applications depend on careful algorithm selection and performance evaluation of the model.

Updated on: 24-Jul-2023

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