For the experiments described later in this paper a Dell Axim X51 PDA was used running the Pocket Interview client software (Figure 1). Audio data was sampled using the PDA microphone at 22kHz with 16-bit depth in 3-second samples. Low-resolution audio samples of 3-second length recorded by PDAs have been demonstrated as sufficient to classify different environments such as offices, streets, bars and car-driving (Ma, Milner, & Smith, 2006).
A PDA running the pocket interview client