Conversational evaluation of artificial bandwidth extension of telephone speech using a mobile handset

Artificial bandwidth extension methods have been developed to improve the quality and intelligibility of narrowband telephone speech. Bandwidth extension methods have typically been evaluated with objective measures or subjective listening-only tests, whereas realistic conversational evaluations have been rare. This paper presents a conversational evaluation of two bandwidth extension methods together with narrowband and wideband speech. The evaluation was performed using a mobile handset with a wired earpiece and microphone both in silence and in simulated street noise. The results indicate that one of the evaluated bandwidth extension methods was significantly preferred over narrowband speech in silence. The results also suggest slight preference for this bandwidth extension method over narrowband speech in street noise. True wideband speech was considered superior to bandwidth-extended and narrowband speech especially in silence.