15. How to create a clean Lombard speech database using loudspeakers

Abstract

The Lombard effect is a phenomenon of increasing the vocal effort that people develop due to, amongst others, the presence of background noise. For example, if the background noise level rises, both pitch and loudness of the voice usually increase, but also the duration of individual speech sounds and the diction may change. In order to investigate this effect in different noise scenarios within either a soundproof room or a car, a reproducible and easily changeable acoustic ambiance simulation has been developed and is presented in this chapter. The noise simulation uses loudspeakers instead of the usual approachwhich uses closed headphones. This increases the realism of the noise scenario for the subject and consequently also the ecological validity of the Lombard speech recordings. To remove the simulated noise from the recordings of the subject’s microphone signal, multichannel signal processing has been implemented to achieve nearly the same speech quality as with a common headset-based noise simulation.