1. INTRODUCTION
One of the crucial pieces of information in a recorded speech signal is the information about the device which was used to record the speech [1]. With a rapid increase in the number of different mobile and recording devices, identifying the recording device from a speech signal has various digital forensics and speech-enabled applications [2]. For example, establishing the source of audio or multi-media evidence in the court of law increases the authenticity of the evidence [2], [3]. This is because digital audio technology, at present, has facilitated the processing, manipulation and editing of audio by using sophisticated tools and software without leaving any perceptible trace [4]. Furthermore, knowing recording device characteristics has the potential to help other critical speech applications such as speech recognition and speaker verification by normalizing recording devices' variability.