# Using 3D Convolutional Neural Networks for Speaker Verification¶

This repository contains the code release for our paper titled as “Text-Independent Speaker Verification Using 3D Convolutional Neural Networks”. The link to the paper is provided as well.

The code has been developed using TensorFlow. The input pipeline must be prepared by the users. This code is aimed to provide the implementation for Speaker Verification (SR) by using 3D convolutional neural networks following the SR protocol.

## DEMO¶

For running a demo, after forking the repository, run the following scrit:

./run.sh


## General View¶

We leveraged 3D convolutional architecture for creating the speaker model in order to simultaneously capturing the speech-related and temporal information from the speakers’ utterances.

### Speaker Verification Protocol(SVP)¶

In this work, a 3D Convolutional Neural Network (3D-CNN) architecture has been utilized for text-independent speaker verification in three phases.

1. At the development phase, a CNN is trained to classify speakers at the utterance-level.

2. In the enrollment stage, the trained network is utilized to directly create a speaker model for each speaker based on the extracted features.

3. Finally, in the evaluation phase, the extracted features from the test utterance will be compared to the stored speaker model to verify the claimed identity.

The aforementioned three phases are usually considered as the SV protocol. One of the main challenges is the creation of the speaker models. Previously-reported approaches create speaker models based on averaging the extracted features from utterances of the speaker, which is known as the d-vector system.

### How to leverage 3D Convolutional Neural Networks?¶

In our paper, we propose to use the 3D-CNNs for direct speaker model creation in which, for both development and enrollment phases, an identical number of speaker utterances is fed to the network for representing the spoken utterances and creation of the speaker model. This leads to simultaneously capturing the speaker-related information and building a more robust system to cope with within-speaker variation. We demonstrate that the proposed method significantly outperforms the d-vector verification system.

## Code Implementation¶

The input pipeline must be provided by the user. The rest of the implementation consider the dataset which contains the utterance-based extracted features are stored in a HDF5 file. However, this is not a necessity because by following the code, it can be seen that the experiments can be done by any file format as long as it is adaptable with TensorFlow.

### Input Pipeline for this work¶

The MFCC features can be used as the data representation of the spoken utterances at the frame level. However, a drawback is their non-local characteristics due to the last DCT 1 operation for generating MFCCs. This operation disturbs the locality property and is in contrast with the local characteristics of the convolutional operations. The employed approach in this work is to use the log-energies, which we call MFECs. The extraction of MFECs is similar to MFCCs by discarding the DCT operation. The temporal features are overlapping 20ms windows with the stride of 10ms, which are used for the generation of spectrum features. From a 0.8- second sound sample, 80 temporal feature sets (each forms a 40 MFEC features) can be obtained which form the input speech feature map. Each input feature map has the dimen- sionality of ζ × 80 × 40 which is formed from 80 input frames and their corresponding spectral features, where ζ is the number of utterances used in modeling the speaker during the development and enrollment stages.

The speech features have been extracted using [SpeechPy] package.

### Implementation of 3D Convolutional Operation¶

The Slim high-level API made our life very easy. The following script has been used for our implementation:

net = slim.conv2d(inputs, 16, [3, 1, 5], stride=[1, 1, 1], scope='conv11')
net = PReLU(net, 'conv11_activation')
net = slim.conv2d(net, 16, [3, 9, 1], stride=[1, 2, 1], scope='conv12')
net = PReLU(net, 'conv12_activation')
net = tf.nn.max_pool3d(net, strides=[1, 1, 1, 2, 1], ksize=[1, 1, 1, 2, 1], padding='VALID', name='pool1')

############ Conv-2 ###############
############ Conv-1 ###############
net = slim.conv2d(net, 32, [3, 1, 4], stride=[1, 1, 1], scope='conv21')
net = PReLU(net, 'conv21_activation')
net = slim.conv2d(net, 32, [3, 8, 1], stride=[1, 2, 1], scope='conv22')
net = PReLU(net, 'conv22_activation')
net = tf.nn.max_pool3d(net, strides=[1, 1, 1, 2, 1], ksize=[1, 1, 1, 2, 1], padding='VALID', name='pool2')

############ Conv-3 ###############
############ Conv-1 ###############
net = slim.conv2d(net, 64, [3, 1, 3], stride=[1, 1, 1], scope='conv31')
net = PReLU(net, 'conv31_activation')
net = slim.conv2d(net, 64, [3, 7, 1], stride=[1, 1, 1], scope='conv32')
net = PReLU(net, 'conv32_activation')
# net = slim.max_pool2d(net, [1, 1], stride=[4, 1], scope='pool1')

############ Conv-4 ###############
net = slim.conv2d(net, 128, [3, 1, 3], stride=[1, 1, 1], scope='conv41')
net = PReLU(net, 'conv41_activation')
net = slim.conv2d(net, 128, [3, 7, 1], stride=[1, 1, 1], scope='conv42')
net = PReLU(net, 'conv42_activation')
# net = slim.max_pool2d(net, [1, 1], stride=[4, 1], scope='pool1')

############ Conv-5 ###############
net = slim.conv2d(net, 128, [4, 3, 3], stride=[1, 1, 1], normalizer_fn=None, scope='conv51')
net = PReLU(net, 'conv51_activation')

# net = slim.conv2d(net, 256, [1, 1], stride=[1, 1], scope='conv52')
# net = PReLU(net, 'conv52_activation')

# Last layer which is the logits for classes
logits = tf.contrib.layers.conv2d(net, num_classes, [1, 1, 1], activation_fn=None, scope='fc')


As it can be seen, slim.conv2d has been used. However, simply by using 3D kernels as [k_x, k_y, k_z] and stride=[a, b, c] it can be turned into a 3D-conv operation. The base of the slim.conv2d is tf.contrib.layers.conv2d. Please refer to official Documentation for further details.

## Disclaimer¶

The code architecture part has been heavily inspired by Slim and Slim image classification library. Please refer to this link for further details.

## Citation¶

If you used this code please kindly cite the following paper:

@article{torfi2017text,
title={Text-Independent Speaker Verification Using 3D Convolutional Neural Networks},
author={Torfi, Amirsina and Nasrabadi, Nasser M and Dawson, Jeremy},
journal={arXiv preprint arXiv:1705.09422},
year={2017}
}


The license is as follows:

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Copyright {2017} {Amirsina Torfi}

you may not use this file except in compliance with the License.
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Please refer to LICENSE file for further detail.

## Contribution¶

We are looking forward to your kind feedback. Please help us to improve the code and make our work better. For contribution, please create the pull request and we will investigate it promptly. Once again, we appreciate your feedback and code inspections.

references

 [SpeechPy] Amirsina Torfi. 2017. astorfi/speech_feature_extraction: SpeechPy. Zenodo. doi:10.5281/zenodo.810392.