Influence of noise on listening effort of adults
Bachelor Thesis of Batlle Roca, Roser
This thesis consists of a study with adults in respect to educational institutions with the aim to evaluate speech perception and listening effort depending on the noise condition. For this purpose three different noise conditions were simulated: speech-shaped noise (SSN), which is characterized for having a similar spectrum as the average long-term spectrum of a speech signal and is considered to be the most effective energy masker of speech; irrelevant and relevant multi-talker babble (IMTB and RMTB, respectively) , which consists of several people simultaneously talking in a foreign language for the listener, in IMTB, or in the same or similar language, in RMTB. These noises were included individually as background noises in a dual-task listening experiment. The primary task consisted of the measurement of response time and percentage of correct words, where participants had to identify the stimuli word and select the corresponding image out of four possible options. Then, the secondary task focused on the measurement of reaction time after a visual stimuli, in which participants had to press a button when the light bulb in the screen turned on. This experiment tested a total of 24 conditions by modifying signal-to-noise ratio, target and distractor position combination and type of noise. The subjects of the experiment were 37 young German speaking adults. The results of the experiment showed that the noise RMTB required more listening effort, among the other possibilities. Further, substantial differences in error rates appeared between position combination, having the worst results when both signals came from the same location (SoNo). In addition, when modifying SNR levels, better results were achieved for high values (p3) . Moreover, a short questionnaire was given to the participants at the end of the test in order to have an evaluation of listening experiment. In this case, results showed that the babble noises were more uncomfortable than the SSN condition. As weIl, the experiment was qualified to be more difficult than expected.