Data Science Mini Project - Speech emotion recognition

Speech emotion recognition, the best ever in python. The best example of it can be seen at call centers. If you ever noticed, call centers employees never talk in the same manner, their way of pitching/talking to the customers changes with customers. Now, this does happen with common people too, but how is this relevant to call centers? Here is your answer, the employees recognize customers’ emotions from speech, so they can improve their service and convert more people. In this way, they are using speech emotion recognition. So, let’s discuss this project in detail.

What is Speech Emotion Recognition?

SER is tough because emotions are subjective and annotating audio is challenging.

What is librosa?

What is JupyterLab?

To run code in the JupyterLab, you’ll first need to run it with the command prompt:

C:\Users\Janvi>jupyter lab

This will open for you a new session in your browser. Create a new Console and start typing in your code. JupyterLab can execute multiple lines of code at once; pressing enter will not execute your code, you’ll need to press Shift+Enter for the same.

Speech Emotion Recognition — Objective

Speech Emotion Recognition

The Dataset


pip install librosa soundfile numpy sklearn pyaudio

If you run into issues installing librosa with pip, you can try it with conda.

Steps for speech emotion recognition python projects

import librosa
import soundfile
import os, glob, pickle
import numpy as np
from sklearn.model_selection import train_test_split
from sklearn.neural_network import MLPClassifier
from sklearn.metrics import accuracy_score


2. Define a function extract_feature to extract the mfcc, chroma, and mel features from a sound file. This function takes 4 parameters- the file name and three Boolean parameters for the three features:

  • mfcc: Mel Frequency Cepstral Coefficient, represents the short-term power spectrum of a sound
  • chroma: Pertains to the 12 different pitch classes
  • mel: Mel Spectrogram Frequency

Learn more about Python Sets and Booleans

Open the sound file with soundfile. SoundFile using with-as so it’s automatically closed once we’re done. Read from it and call it X. Also, get the sample rate. If chroma is True, get the Short-Time Fourier Transform of X.

Let result be an empty numpy array. Now, for each feature of the three, if it exists, make a call to the corresponding function from librosa.feature (eg- librosa.feature.mfcc for mfcc), and get the mean value. Call the function hstack() from numpy with result and the feature value, and store this in result. hstack() stacks arrays in sequence horizontally (in a columnar fashion). Then, return the result.

def extract_feature(file_name, mfcc, chroma, mel):
with soundfile.SoundFile(file_name) as sound_file:
X ="float32")
if chroma:
if mfcc:
mfccs=np.mean(librosa.feature.mfcc(y=X,sr=sample_rate, n_mfcc=40).T,axis=0)
result=np.hstack((result, mfccs))
if chroma:
chroma=np.mean(librosa.feature.chroma_stft(S=stft, sr=sample_rate).T,axis=0)
result=np.hstack((result, chroma))
if mel:
mel=np.mean(librosa.feature.melspectrogram(X, sr=sample_rate).T,axis=0)
result=np.hstack((result, mel))
return result


3. Now, let’s define a dictionary to hold numbers and the emotions available in the RAVDESS dataset, and a list to hold those we want- calm, happy, fearful, disgust.

observed_emotions=['calm', 'happy', 'fearful', 'disgust']


4. Now, let’s load the data with a function load_data() — this takes in the relative size of the test set as parameter. x and y are empty lists; we’ll use the glob() function from the glob module to get all the pathnames for the sound files in our dataset. The pattern we use for this is: “*/Actor_*/*.wav”. This is because our dataset looks like this:


So, for each such path, get the basename of the file, the emotion by splitting the name around ‘-’ and extracting the third value:

Using our emotions dictionary, this number is turned into an emotion, and our function checks whether this emotion is in our list of observed_emotions; if not, it continues to the next file. It makes a call to extract_feature and stores what is returned in ‘feature’. Then, it appends the feature to x and the emotion to y. So, the list x holds the features and y holds the emotions. We call the function train_test_split with these, the test size, and a random state value, and return that.

def load_data(test_size=0.2):
for file in glob.glob("/content/sample_data/mini project/*.wav"):
if emotion not in observed_emotions:
feature=extract_feature(file, mfcc=True, chroma=True, mel=True)
return train_test_split(np.array(x), y, test_size=test_size, random_state=9)


5. Time to split the dataset into training and testing sets! Let’s keep the test set 25% of everything and use the load_data function for this.



6. Observe the shape of the training and testing datasets:

print((x_train.shape[0], x_test.shape[0]))


7. And get the number of features extracted.

print(f'Features extracted: {x_train.shape[1]}')

Output Screenshot:

8. Now, let’s initialize an MLPClassifier. This is a Multi-layer Perceptron Classifier; it optimizes the log-loss function using LBFGS or stochastic gradient descent. Unlike SVM or Naive Bayes, the MLPClassifier has an internal neural network for the purpose of classification. This is a feedforward ANN model.

model=MLPClassifier(alpha=0.01, batch_size=256, epsilon=1e-08, hidden_layer_sizes=(300,), learning_rate='adaptive', max_iter=500)


9. Fit/train the model.,y_train)

Output Screenshot:

10. Let’s predict the values for the test set. This gives us y_pred (the predicted emotions for the features in the test set).



11. To calculate the accuracy of our model, we’ll call up the accuracy_score() function we imported from sklearn. Finally, we’ll round the accuracy to 2 decimal places and print it out.

accuracy=accuracy_score(y_true=y_test, y_pred=y_pred)
print("Accuracy: {:.2f}%".format(accuracy*100))

Output Screenshot:


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