Noise in Nature Environmental Stressor or Constraint on Restoration?

Staffan HyggeNoise, memory and learning(Buller, minne och inlrning)

Staffan Hygge Environmental PsychologyDepartment of Building, Energy and Environmental EngineeringFaculty of Engineering and Sustainable DevelopmentUniversity of GvleBo i Ro, Stockholm Oct 20th, 2015

Contents of my talkText based reading and learning in noiseClassroom experiments on noise and memory of a textA natural experiment on chronic aircraft noise and cognition in children (the Munich study) Laboratory experiments on noise and memory systemsWHO Burden of Disease from environmental noise

Speech based listening and learning in noise or degraded speechSpeech intelligibility, recall and memory Signal-to-Noise Ratio (SNR) and Reverberation time (RT) 2

Classroom Experiments - Results

3 The Munich airport noise study on children's cognition

Children's cognition, some of the results Difficult word list Difficult paragraphs Long-term recall

The Munich airport noise study on children

Recall of the textAgegroup55-65 years35-45 years18-20 years13-14 yearsMeans10.08.06.04.02.00.0Noise groupsNo noiseRoad traffic noiseIrrelevant speech

Laboratory experiments on noise and memory systems Memory of the text

Laboratory experiments on noise and memory systems Aggregated measuresStructural Equation ModelConceptual diagram of a modified Model M4 for a single sample with the addition of a separate 1st-order factor (Text) for the text memory items (RCLtxt, RCGtxt) loaded on the 2nd-order factor Episodic, with the corresponding indicators, standardized loadings, and free error covariances (2 = 90.17, df= 74, p = .097, RMSEA = .028).

Noise conditions did not significantly change the fit of the Structural Equation Model!

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WHO, 2011

Chapter: Environmental noise and cognitive impairment in children

http://www.euro.who.int/__data/assets/pdf_file/0008/136466/e94888.pdf Three field studies combinedFigure. Dose-effect curves from epidemiological field studies with chronic noise exposureRd = Reading, Rcl = memory, recall1 Recall, children, old airport, Hygge et al. (2002) - longitudinal2 Recall, children, new airport, Hygge et al. (2002) - longitudinal3 Reading, children, old airport, Hygge et al. (2002) - longitudinal4 Reading, children, new airport, Hygge et al. (2002) - longitudinal5 Reading, children, airport, Stansfeld et al. (2005) cross-sectional6 Free recall, children, road traffic, Lercher et al. (2003) crosssectional

5 Rd 1 Rcl 3 Rd 4 Rd2 Rcl6 Rcl

EUR-A countries can be calculated (Table 3.3). The absolute DALY for the EUR-A countries, with an estimated total population of 420 503 million, is therefore 45 036.Speech based listening and learning in noise or degraded speech

Exploring how spoken information, in contrast to written information, is processed in working memory (WM) and mediated to long-term memory

How much does SNR and RT influence recall and memory?Are the effects of SNR and RT additive or do they interact?

Knowing more about their additive or interactive effects has both a theoretical and practical value.Speech intelligibility and memory Reverberation time and background noise

Direct sound: The part of the sound that goes the shortest distance from speaker to listenerReflected sound: The part of the sound that reaches the listenser after having been reflected by different surfaces in the room. Reaches the ear later than the direct soundIndoor sound pressure level as a function of the distance to the sound source

-6dB with doubling distanceConstant sound levelDistance from source Sound pressure level, dB(A)Near field Reverberation fieldAn example:When a teacher speaks at 66 dB(A), that level drops to 52 dB(A) 6 m out in an ordinary classroom. This is only 7 dB(A) above a background level of 45 dB(A)

A long reverberation time may disturb speech perceptionReflected sounds that arrive later than 35-40 ms after the direct sound interfere with the direct sound and disturb speech perception by masking the direct soundThe largest and most critical masking effects are vowels that mask subsequent consonants, which have a lower sound level higher frequency, but are more important for speech intelligibilityAt the same SNR-level a shorter reverberation time therefore gives a clearer signal and better speech perception15Does reverberation time cause a problem in schools? Measurements and recordings in two classrooms A short lectureA classroom with a long reverberation time 1.6 - 2.0 s in the lower frequency bands

Another classroom with a reverberation time around 0.3 s in all frequency bands

Results: Means 2.16 (long RT) and 4.00 (short RT), F(1,17) = 16.60, p < .001To hear but not rememberReverberation time (RT) and signal-to-noise ratio (SNR)Participants heard word lists and repeated the words directlyShort RT (0.5 s)Long RT (1.2 s)13.010.8Number of correctly recalled words

p =.025Conclusion: Fewer word are remembered after hearing them under them under a low signal-to-noise (SNR) ratio and a long reverberation timeSNR 27 dBGoodSNR 4 dBBad11.08.5p