Vowel classification with combining pitch detection and one-dimensional convolutional neural network based classifier for gender identification

Human speech signals may contain specific information regarding a speaker's characteristics, and these signals can be very useful in applications involving interactive voice response (IVR) and automatic speech recognition (ASR). For IVR and ASR applications, speaker classification into different ages and gender groups can be applied in human–machine interaction or computer-based interaction systems for customised advertisement, translation (text generation), machine dialog systems, or self-service applications. Hence, an IVR-based system dictates that ASR should function through users' voices (specific voice-frequency bands) to identify customers' age and gender and interact with a host system. In the present study, we intended to combine a pitch detection (PD)-based extractor and a voice classifier for gender identification. The Yet Another Algorithm for Pitch Tracking (YAAPT)-based PD method was designed to extract the voice fundamental frequency (F₀) from non-stationary speaker's voice signals, allowing us to achieve gender identification, by distinguishing differences in F₀ between adult females and males, and classify voices into adult and children groups. Then, in vowel voice signal classification, a one-dimensional (1D) convolutional neural network (CNN), consisted of a multi-round 1D kernel convolutional layer, a 1D pooling process, and a vowel classifier that could preliminary divide feature patterns into three level ranges of F₀, including adult and children groups. Consequently, a classifier was used in the classification layer to identify the speakers' gender. The proposed PD-based extractor and voice classifier could reduce complexity and improve classification efficiency. Acoustic datasets were selected from the Hillenbrand database for experimental tests on 12 vowels classifications, and K-fold cross-validations were performed. The experimental results demonstrated that our approach is a very promising method to quantify the proposed classifier's performance in terms of recall (%), precision (%), accuracy (%), and F1 score.