An exploratory investigation of speech recognition thresholds in noise with auralisations of two reverberant rooms

Acoustic Sensing Analytics Applied to Speech in Reverberation Conditions

The paper aims to discuss a case study of sensing analytics and technology in acoustics when applied to reverberation conditions. Reverberation is one of the issues that makes speech in indoor spaces challenging to understand. This problem is particularly critical in large spaces with few absorbing or diffusing surfaces. One of the natural remedies to improve speech intelligibility in such conditions may be achieved through speaking slowly. It is possible to use algorithms that reduce the rate of speech (RoS) in real time. Therefore, the study aims to find recommended values of RoS in the context of STI (speech transmission index) in different acoustic environments. In the experiments, speech intelligibility for six impulse responses recorded in spaces with different STIs is investigated using a sentence test (for the Polish language). Fifteen subjects with normal hearing participated in these tests. The results of the analytical analysis enabled us to propose a curve specifying the maximum RoS values translating into understandable speech under given acoustic conditions. This curve can be used in speech processing control technology as well as compressive reverse acoustic sensing.

Recall of Reverberant Speech in Quiet and Four-Talker Babble Noise

Using behavioral evaluation of free recall performance, we investigated whether reverberation and/or noise affected memory performance in normal-hearing adults. Thirty-four participants performed a free-recall task in which they were instructed to repeat the initial word after each sentence and to remember the target words after each list of seven sentences, in a 2 (reverberation) × 2 (noise) factorial design. Pupil dilation responses (baseline and peak pupil dilation) were also recorded sentence-by-sentence while the participants were trying to remember the target words. In noise, speech was presented at an easily audible level using an individualized signal-to-noise ratio (95% speech intelligibility). As expected, recall performance was significantly lower in the noisy environment than in the quiet condition. Regardless of noise interference or reverberation, sentence- baseline values gradually increased with an increase in the number of words to be remembered for a subsequent free-recall task. Long reverberation time had no significant effect on memory retrieval of verbal stimuli or pupillary responses during encoding.