Comparisons between simulated and in-situ measured speech intelligibility based on (binaural) room impulse responses

Abstract

This study systematically compares acoustic simulation and in-situ measurement in terms of speech transmission index (STI), speech intelligibility scores and relationship curves when considering (binaural) room impulse response and four general room conditions, namely, an office, a laboratory, a multimedia lecture hall and a semi-anechoic chamber. The results reveal that STI can be predicted accurately by acoustic simulation (using room acoustics software ODEON) when there is a good agreement between the virtual models and the real rooms and that different reverberation time (RT) and signal-to-noise ratio (SNR) may exert less significant influence on the simulated STI. However, subjective intelligibility may be overestimated when using acoustic simulation due to the head-related transfer function (HRTF) filter used, and the score bias may be minimal and difficult to detect in everyday situations. There is no obvious score tendency caused by different RT, though with the decrease in the SNR, score bias may increase. Overall, considering that the accurate acoustic modelling of rooms is often problematic, it is difficult to obtain accurate speech intelligibility prediction results using a simulation technique, especially when the room has not yet been built.

Using listening effort assessment in the acoustical design of rooms for speech

“…Literature results showed that a good agreement between real and virtual data can be obtained [31] but consistency in speech intelligibility results seems to decrease for shorter reverberation times and too noisy sound fields [32,33]. Furthermore, the details of the head related transfer functions (HRTF) employed in the simulations might influence the results to a notable extent [34]. Despite several specific studies on speech intelligibility and auralization, the ecological validation of the RT and LE metrics, that is a proof of correspondence between the values retrieved under natural and synthetized conditions, is still lacking.…”

A combined sound field prediction method in small classrooms

“…Previous studies on acoustic sound filed simulations of normal-sized classrooms were always based on the hybrid geometrical acoustic methods. [12][13][14][15][16] However, when it comes to small rooms, geometrical acoustic prediction methods appear to be flawed due to the inherent neglect of important low frequency wave effects, such as standing waves, diffraction, and interference. In order to assess the aural significance of using more accurate lowfrequency modelling and applied in a real room, several combined wave-based and geometric studies were proposed in the previous study.…”

“…The geometrical acoustical methods were widely applied in predicting sound fields in large spaces. [12][13][14][15][16][17] However, when it comes to small rooms, geometrical acoustic prediction methods appear to be flawed due to the inherent negligence of important low frequency wave effects, such as standing waves, diffraction, and interference. While in small rooms, it is known that inherent simplifying assumptions made for geometric acoustic methods limit the applicable frequency range to frequencies higher than the Schroeder frequency.…”