Shizuma Yamaguchi

A psychological evaluation method for fluctuating random noise based on fuzzy set theory

Abstract In psychological noise evaluation, subjective judgment of the acoustical stimulus causes fuzziness. By paying special attention to the fuzziness of the subjective impression, the categorized psychological evaluation is quantitatively understood as the fuzzy event. The so-called discrete-type membership function in the field of fuzzy set theory is used as a practical method for discussing the relationship between the objective acoustical stimulus and the subjective human response. The patterns of discrete-type membership functions are determined by using the data actually observed to give the psychological impression. Next, a new method of evaluating the psychological impression is proposed for the case when subjects are exposed to the fluctuating random noise of arbitrary probability distribution. Finally, the validity and usefulness of the proposed method are confirmed experimentally by applying it to the data actually observed.

A practical prediction method of psychological response to arbitrary non-white random noise based on simplified patterns of membership functions

In psychological noise evaluation, the fuzziness caused by the human subjective judgment for the acoustical stimulus essentially exists. By paying special attention to the fuzziness of the subjective impression, the categorized psychological evaluation is grasped quantitatively as the fuzzy event. That is, the so-called membership function in the field of fuzzy set theory is used as a method for discussing the relationship between the objective acoustical stimulus and the subjective human response. The set of eight simplified patterns of membership functions is first established by using the data obtained from an actual psychological experiment in the case when the test subjects are exposed to the octave-band-limited white noise with center frequency fcK (K = 1, 2, …, 8). Next, the membership functions for the psychological impression are estimated by use of the above set of eight simplified patterns, in a case when the test subjects are exposed to an arbitrary non-white random noise. Further, a method for evaluating the psychological response is proposed by using the concept of the fuzzy probability. Finally, the validity and the usefulness of the proposed method are confirmed experimentally by applying it to the actually observed data.

Psychological impressions and listening score when listening to audio signals composed of monosyllables and words, while subject to meaningless steady noise—introduction of weighted-mean spectral distance

Abstract A useful index for evaluating two psychological impressions of annoyance, speech audibility, and the listening score, when listening to audio signals composed of monosyllables and words, while subject to meaningless steady noise is discussed. More specifically, eight evaluation indices ( SN, AI, SIL, WSPD , etc.) are introduced that reflect the mutual relationships between the spectrum level of the speech peaks and that of the noise. After careful consideration of the relationships between these indices and the psychological impressions/listening score, WSPD can be selected as a useful index. Next, prediction problems of the psychological impressions/listening score are considered. The predicted values of the psychological impressions/listening score are compared with experimental data. The predicted values are in good agreement with the observed results.

Psychological impression and listening score while listening to audio signal under meaningless steady noise

Abstract The indices for evaluating psychological impression and listening score are first introduced in the case of listening to a Japanese monosyllabic audio signal while subjected to meaningless steady noise. Hereupon, the mutual relationship between the power spectrum level of audio signal and that of external noise is reflected in the above evaluation indices. Next, estimation and/or prediction problems of the psychological impression and listening score are discussed. The predicted values of the psychological impression and listening score are compared with the experimental observed data. A useful index is discussed, considering consistency between predicted and observed values.

A method for predicting psychological response to meaningless random noise based on fuzzy system model

Abstract By examining the memory effect and the fuzziness of human subjective judgment, the fuzzy relation between physical meaningless random noise stimuli and the psychological response is clarified quantitatively based on bivariate membership functions. Two variables describing the sound pressure level of the random noise stimulus and the temporal change in the level are employed as the fundamental variables for the bivariate membership functions. A method for predicting the psychological response to such stimuli is proposed, introducing the concept of fuzzy probability. The validity and usefulness of the proposed method is confirmed experimentally by applying the method to observed data. The theoretical calculations are in good agreement with the experimental results.

A FUNDAMENTAL CONSIDERATION ON EVALUATING NOISE PRODUCED BY ROAD TRAFFIC CONTROLLED BY TRAFFIC SIGNALS

Abstract The actual road traffic noise that we encounter is affected by traffic signals. So, the random noise fluctuations usually exhibit periodic nonstationary properties caused by the periodic temporal change of traffic flow. Also, statistical parameters such as the equivalent sound level (Leq) and the median value of sound level (L50) are important for noise evaluation and regulation problems. In this paper, a new approximate probability density function (pdf) of nonstationary noise level fluctuation is proposed in a case where the road traffic flow is controlled by traffic signals, by paying special attention to the periodicity of fluctuation patterns of the cumulant statistics of noise level. Next, the explicit expressions of Leq and L50 are derived as an application of the above theory. The effects of the nonstationary properties caused by the traffic signals on the noise evaluation indices, Leq and L50, are shown quantitatively. Finally, statistical evaluation methods for the dispersion of Leq and L50 estimations caused by the finiteness of the sample sizes are theoretically considered, in a case when Leq and L50 for the periodic nonstationary road traffic noise are experimentally estimated by using the usual sound level meter and sampling method.

The effect of interest in speech on psychological response to external noise

The relationship between the human psychological response to external noise when listening to interesting speech and to uninteresting speech is first considered by using membership functions established from observed data. The fuzzy relation between the sound pressure level of the speech and that of the external noise is estimated approximately by univariate membership functions established on the universe of the signal-to-noise ratio. Next, a method for evaluating the psychological response by using the concept of fuzzy probability is proposed. Finally, the validity of the evaluation method is experimentally confirmed by applying it to observed data.

A fundamental consideration on estimating Leq of specific noise under the existence of background noise

Abstract In the practical measurement and/or evaluation problems of environmental noise such as the road traffic noise and the urban noise, etc., it is very often that the actually observed noise data are contaminated by the surrounding background noise. Furthermore, it is a rare occurrence that the statistical properties of the background noise are known in advance. When the values of the mean value and the dynamic range of the specific noise level fluctuation are larger than those of the background noise level, the observed data with fairly large level values can be approximately regarded as the specific noise level data. In this paper, three new trials for estimating the equivalent sound pressure level ( L eq ) of the specific noise based on the above partially observed data are considered, specifically under the condition that the mean value and the dynamic range of the specific noise are larger than those of the background noise. The validity and the effectiveness of three proposed methods are discussed concretely by the simulation experiment.

A New Model of Rating Scale Method Considering Context Effects Based on Fuzzy Logic and its Application for a Psychological Response to the Acoustic Noise

The rating scale method and/or the method of successive categories are widely used for rating objects using the successive categories. This paper points out several problems with the conventional method and studies the rating problems from the viewpoint that the rating conducts can be regarded as a kind of fuzzy and subjective logical judging process. The fuzziness and the subjectivity are derived from the meaning of rating words and the difference of feeling to the stimulus. The quality and the structure of the judging process, especially the context effect are clearly discussed in Fuzzy Theory. These studies are developed into a dynamic rating system in order to rate the acoustic noise in time series. The validity of the studies and the usefulness of the system are experimentally confirmed by applying it to the noise rating problem and by clarifying the criterion of judgment and the context effect.

A statistical method of the practical probability expression for nonstationary ship noise fluctuations and its experimental confirmation

Abstract Many people now enjoy marine sports such as skin diving and scuba diving in shallow water areas. Acoustic signals through an underwater loudspeaker can be used as a simple and effective way of preventing diving accidents. The use of audio signals is very important since divers usually have no communication apparatus. It is necessary and timely to investigate the state of the shallow water acoustical environment for the audio frequency bandwidth. Theoretical approximate probability expression for the sound power fluctuations from a moving ship (an important sound source) is first derived in the form of an infinite expansion series, by paying special attention to the standard shape of the sound pressure spectrum. Successively, for the sake of real applications, a practical probability expression in the form of a finite weighted sum of Gaussian distribution functions is proposed. The validity and the usefulness of the theoretical method have been experimentally confirmed using a digital simulation technique and has also been applied to actually observed ship noise data. These experimental results are in good agreement with the theory.