624 research outputs found
Likelihood-Maximizing-Based Multiband Spectral Subtraction for Robust Speech Recognition
Automatic speech recognition performance degrades significantly when speech is affected by environmental noise. Nowadays, the major challenge is to achieve good robustness in adverse noisy conditions so that automatic speech recognizers can be used in real situations. Spectral subtraction (SS) is a well-known and effective approach; it was originally designed for improving the quality of speech signal judged by human listeners. SS techniques usually improve the quality and intelligibility of speech signal while speech recognition systems need compensation techniques to reduce mismatch between noisy speech features and clean trained acoustic model. Nevertheless, correlation can be expected between speech quality improvement and the increase in recognition accuracy. This paper proposes a novel approach for solving this problem by considering SS and the speech recognizer not as two independent entities cascaded together, but rather as two interconnected components of a single system, sharing the common goal of improved speech recognition accuracy. This will incorporate important information of the statistical models of the recognition engine as a feedback for tuning SS parameters. By using this architecture, we overcome the drawbacks of previously proposed methods and achieve better recognition accuracy. Experimental evaluations show that the proposed method can achieve significant improvement of recognition rates across a wide range of signal to noise ratios
Speech Recognition of Isolated Arabic words via using Wavelet Transformation and Fuzzy Neural Network
In this paper two new methods for feature extraction are presented for speech recognition the first method use a combination of linear predictive coding technique(LPC) and skewness equation. The second one(WLPCC) use a combination of linear predictive coding technique(LPC), discrete wavelet transform(DWT), and cpestrum analysis. The objective of this method is to enhance the performance of the proposed method by introducing more features from the signal. Neural Network(NN) and Neuro-Fuzzy Network are used in the proposed methods for classification. Test result show that the WLPCC method in the process of features extraction, and the neuro fuzzy network in the classification process had highest recognition rate for both the trained and non trained data. The proposed system has been built using MATLAB software and the data involve ten isolated Arabic words that are (الله، Ù…Øمد، خديجة، ياسين، يتكلم، الشارقة، لندن، يسار، يمين، Ø£Øزان), for fifteen male speakers. The recognition rate of trained data is (97.8%) and non-trained data is (81.1%). Keywords: Speech Recognition, Feature Extraction, Linear Predictive Coding (LPC),Neural Network, Fuzzy networ
PhantomSound: Black-Box, Query-Efficient Audio Adversarial Attack via Split-Second Phoneme Injection
In this paper, we propose PhantomSound, a query-efficient black-box attack
toward voice assistants. Existing black-box adversarial attacks on voice
assistants either apply substitution models or leverage the intermediate model
output to estimate the gradients for crafting adversarial audio samples.
However, these attack approaches require a significant amount of queries with a
lengthy training stage. PhantomSound leverages the decision-based attack to
produce effective adversarial audios, and reduces the number of queries by
optimizing the gradient estimation. In the experiments, we perform our attack
against 4 different speech-to-text APIs under 3 real-world scenarios to
demonstrate the real-time attack impact. The results show that PhantomSound is
practical and robust in attacking 5 popular commercial voice controllable
devices over the air, and is able to bypass 3 liveness detection mechanisms
with >95% success rate. The benchmark result shows that PhantomSound can
generate adversarial examples and launch the attack in a few minutes. We
significantly enhance the query efficiency and reduce the cost of a successful
untargeted and targeted adversarial attack by 93.1% and 65.5% compared with the
state-of-the-art black-box attacks, using merely ~300 queries (~5 minutes) and
~1,500 queries (~25 minutes), respectively.Comment: RAID 202
Privacy-preserving and Privacy-attacking Approaches for Speech and Audio -- A Survey
In contemporary society, voice-controlled devices, such as smartphones and
home assistants, have become pervasive due to their advanced capabilities and
functionality. The always-on nature of their microphones offers users the
convenience of readily accessing these devices. However, recent research and
events have revealed that such voice-controlled devices are prone to various
forms of malicious attacks, hence making it a growing concern for both users
and researchers to safeguard against such attacks. Despite the numerous studies
that have investigated adversarial attacks and privacy preservation for images,
a conclusive study of this nature has not been conducted for the audio domain.
Therefore, this paper aims to examine existing approaches for
privacy-preserving and privacy-attacking strategies for audio and speech. To
achieve this goal, we classify the attack and defense scenarios into several
categories and provide detailed analysis of each approach. We also interpret
the dissimilarities between the various approaches, highlight their
contributions, and examine their limitations. Our investigation reveals that
voice-controlled devices based on neural networks are inherently susceptible to
specific types of attacks. Although it is possible to enhance the robustness of
such models to certain forms of attack, more sophisticated approaches are
required to comprehensively safeguard user privacy
Robust text independent closed set speaker identification systems and their evaluation
PhD ThesisThis thesis focuses upon text independent closed set speaker
identi cation. The contributions relate to evaluation studies in the
presence of various types of noise and handset e ects. Extensive
evaluations are performed on four databases.
The rst contribution is in the context of the use of the Gaussian
Mixture Model-Universal Background Model (GMM-UBM) with
original speech recordings from only the TIMIT database. Four main
simulations for Speaker Identi cation Accuracy (SIA) are presented
including di erent fusion strategies: Late fusion (score based), early
fusion (feature based) and early-late fusion (combination of feature and
score based), late fusion using concatenated static and dynamic
features (features with temporal derivatives such as rst order
derivative delta and second order derivative delta-delta features,
namely acceleration features), and nally fusion of statistically
independent normalized scores.
The second contribution is again based on the GMM-UBM
approach. Comprehensive evaluations of the e ect of Additive White
Gaussian Noise (AWGN), and Non-Stationary Noise (NSN) (with and
without a G.712 type handset) upon identi cation performance are
undertaken. In particular, three NSN types with varying Signal to
Noise Ratios (SNRs) were tested corresponding to: street tra c, a bus
interior and a crowded talking environment. The performance
evaluation also considered the e ect of late fusion techniques based on
score fusion, namely mean, maximum, and linear weighted sum fusion.
The databases employed were: TIMIT, SITW, and NIST 2008; and 120
speakers were selected from each database to yield 3,600 speech
utterances.
The third contribution is based on the use of the I-vector, four
combinations of I-vectors with 100 and 200 dimensions were employed.
Then, various fusion techniques using maximum, mean, weighted sum
and cumulative fusion with the same I-vector dimension were used to
improve the SIA. Similarly, both interleaving and concatenated I-vector
fusion were exploited to produce 200 and 400 I-vector dimensions. The
system was evaluated with four di erent databases using 120 speakers
from each database. TIMIT, SITW and NIST 2008 databases were
evaluated for various types of NSN namely, street-tra c NSN,
bus-interior NSN and crowd talking NSN; and the G.712 type handset
at 16 kHz was also applied.
As recommendations from the study in terms of the GMM-UBM
approach, mean fusion is found to yield overall best performance in terms
of the SIA with noisy speech, whereas linear weighted sum fusion is
overall best for original database recordings. However, in the I-vector
approach the best SIA was obtained from the weighted sum and the
concatenated fusion.Ministry of Higher Education
and Scienti c Research (MoHESR), and the Iraqi Cultural Attach e,
Al-Mustansiriya University, Al-Mustansiriya University College of
Engineering in Iraq for supporting my PhD scholarship
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