Messung und Bewertung von Lärm in Kindertagesstätten

Noise is one of the main factors for stress and discomfort at working places in child care facilities, and it is also one major reason for job changes and early retirements. This study investigated noise at a kindergarten site comprising several groups of children of the two typical age groups 0 to 3 years (German "Krippe") and 3 to 6 years (German ,.Kindergarten"). Noise was assessed subjectively by means of a questionnaire, as well as objectively by means of long-Term level measurements in 12 different rooms. The subjective evaluation indicated that playing children and toy noise were the most dominant noise sources. It also showed a strong influence of day time, week day, and season on perceived noise. This was also reflected in the long-Term level measurement in the group rooms, where median values of sound pressure level distributions showed similar trends. Peak sound pressure levels measured for blocks of 125 ms exceeded 90 dBA for the majority of days in the meas urement period of more than 30 weeks. In addition to the noise assessment, a collection of simple noise reduction measures was collected from interviews and previous literature. This catalog of measures was presented to and partly implemented by child care workers in the facility under investigation. A subjective assessment of the implemented measures one year later showed a large satisfaction, indicating that subjective noise reduction can be achieved by relatively simple low-price measures

ASR-based, single-ended modeling of listening effort - a tool for TV sound engineers

This paper reviews our research approaches towards a listening effort model and its applications as a tool to automatically measure and display the perceived listening effort required to understand speech in a variety of different background sounds. It is single-ended, i.e. it does not require a clean speech reference, and is based on an automatic speech recognition (ASR) system. Speech distortions and interfering background sounds increase the uncertainty of the ASR system, which can be quantified and mapped to a perceptually interpretable scale using a psychoacoustic modeling approach. This performance measure correlates well with mean subjective listening effort ratings for a variety of distortions and acoustic backgrounds typical for TV broadcast material (r > 0.9). In principle, the tool is applicable to be integrated as a software plugin for digital audio workstations (DAWs) to support the work of sound engineers, or in other applications such as speech quality monitoring of communication channels or real-time control of signal-enhancement algorithms

Measurement and prediction of speech intelligibility in noise and reverberation for different sentence materials, speakers, and languages

The present study investigates the role of the speech material type, speaker, and language for speech intelligibility in noise and reverberation. The experimental data are compared to predictions of the speech transmission index. First, the effect of noise only, reverberation only, and the combination of noise and reverberation was systematically investigated for two types of sentence tests. The hypothesis to be tested was that speech intelligibility is more affected by reverberation when using an open-set speech material consisting of everyday sentences than when using a closed-set test with syntactically fixed and semantically unpredictable sentences. In order to distinguish between the effect of speaker and language on speech intelligibility in noise and reverberation, the closed-set speech material was recorded using bilingual speakers of German-Spanish and German-Russian. The experimental data confirmed that the effect of reverberation was stronger for an open-set test than for a closed-set test. However, this cannot be predicted by the speech transmission index. Furthermore, the inter-language differences in speech reception thresholds were on average up to 5 dB, whereas inter-talker differences were of about 3 dB. The Spanish language suffered more under reverberation than German and Russian, what again challenged the predictions of the speech transmission index