Applications in Audio

Saturday, October 21, 9:00 am — 12:00 pm (Rm 1E12)

Chair:
Elisabeth McMullin, Samsung Research America - Valencia, CA USA

P17-1 Challenges of Audio Forensic Evaluation from Personal Recording Devices—Robert C. Maher, Montana State University - Bozeman, MT, USA
Typical law enforcement audio forensic investigations involve audio evidence recorded under less-than-ideal circumstances by mobile phones, surveillance systems, and personal audio recorders. Moreover, the audio information is often transmitted and stored using a data compression algorithm such as a speech coder (e.g., VSELP) or a wideband audio coder (e.g., MP3). There are few systematic studies of the signal behavior of these systems for forensically-relevant audio material, and this may discourage a forensic examiner from using such acoustic evidence to draw reliable conclusions. This paper includes simulation and evaluation of personal audio recording systems in the context of audio forensics. The results indicate areas of strength and weakness in the forensic realm. 

P17-2 An Acoustic Study of Airbag Deployment in Vehicles—John Vanderkooy, University of Waterloo - Waterloo, ON, Canada; Kevin Krauel, University of Waterloo - Waterloo, Ontario, Canada
This study shows the acoustic pressures produced in typical airbag deployments and introduces the topic to the AES. Two representative vehicles were tested: a 2005 Pontiac Montana SV6 minivan and a 2006 Mazda 3 hatchback. Microphones were placed at the left driver ear, right passenger ear, and rear seat positions. Wideband pressure data was obtained for each of the steering wheel, passenger, and any optional side airbags. Our data agrees with the plethora of studies of earlier work. Weighted and unweighted peak SPL levels are calculated for various deployment scenarios. The influence of the cabin volume and the vents of the vehicles are discussed. Concerns over hearing loss, possible eardrum perforation, and other hearing-related symptoms are considered, gleaned mainly from important earlier studies. Some aspects are counterintuitive.   

P17-3 CLEAR: Conditionally Lossless Encoding under Allowed Rates for Low-Delay Sound Data Transmission—Ryosuke Sugiura, NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation - Kanagawa, Japan; Yutaka Kamamoto, NTT Communication Science Laboratories - Kanagawa, Japan; Noboru Harada, NTT Communicatin Science Labs - Atsugi-shi, Kanagawa-ken, Japan; Takahito Kawanishi, 1NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation - Kanagawa, Japan; Takehiro Moriya, NTT Communication Science Labs - Atsugi-shi, Kanagawa-ken, Japan
We present in this paper a near-lossless full-band stereo compression scheme, Conditionally Lossless Encoding under Allowed Rates (CLEAR), aiming at its use in real-time transmission of sound data, sounds to be mixed or processed after transmitted. Using uniform quantizer with MPEG-4 Audio Lossless Coding (ALS) and adaptive pre- and post-processing, CLEAR controls the encoding bit rate with maximum fidelity of reconstructed signals. Objective experiments show an enhancement in signal to noise ratio (SNR) and from conventional low-delay codecs with compatible perceptual quality. Additionally, companding-based perceptual weighting designed for CLEAR is shown to make an improvement in Perceptual Evaluation of Audio Quality (PEAQ). 

P17-4 A New THD+N Algorithm for Measuring Today's High Resolution Audio Systems—Alfred Roney, MathWorks, Inc. - Natick, MA, USA; Steve Temme, Listen, Inc. - Boston, MA, USA
We present a mathematical definition of Total Harmonic Distortion + Noise suitable for testing high-resolution digital audio systems. This formal definition of the "distortion analyzer" mentioned in AES17 defines THD+N as the RMS error of fitting a sinusoid to a noisy and distorted sequence of measurements. We present the key theoretical result that under realistic conditions a modern THD+N analyzer is well-described by a Normal probability distribution with a simple relationship between relative error and analysis dwell time. These findings are illustrated by comparing the output of a commercial distortion analyzer to our proposed method using Monte Carlo simulations of noisy signal channels. We will demonstrate that the bias of a well-designed distortion analyzer is negligible. 

P17-5 Influences of a Key Map on Soundwalk Exploration with a Textile Sonic Map—Alessia Milo, Queen Mary University of London - London, UK; Nick Bryan-Kinns, Queen Mary University of London - London, UK; Media and Arts Technology Centre for Doctoral Training; Joshua D. Reiss, Queen Mary University of London - London, UK
Sonic maps are an increasingly popular form of exploring soundscapes and are a possible means of communicating the experience of a soundwalk. We describe how a printed key influenced exploration of an interactive textile sonic map. We explain the technology behind the map, employing capacitive sensing and real-time audio processing. The sonic map contained 18 binaural recordings extracted from a soundwalk. Thirty participants explored the map. The strengths and limitations of the interfaces were established, and participants’ modes of exploration were identified. Results show how the use of the key map levelled the location preference. The participants’ experience with the interface suggested possible uses of e-textiles for soundscape awareness promotion and studies and in the field of interactive audio. 

P17-6 Challenges of IoT Smart Speaker Testing—Glenn Hess, Indy Acoustic Research LLC - Indianapolis, IN, USA; Daniel Knighten, Listen, Inc. - Boston, MA, USA
Quantitatively measuring the audio characteristics of IoT (Internet of Things) smart speakers presents several novel challenges. We discuss overcoming the practical challenges of testing such devices and demonstrate how to measure frequency response, distortion, and other common audio characteristics. In order to make these measurements, several measurement techniques and algorithms are presented  that allow us to move past the practical difficulties presented by this class of emerging audio devices. We discuss test equipment requirements, selection of test signals, and especially overcoming the challenges around injecting and extracting test signals from the device.