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Important researches were made, taking into account massive numbers of previous study results, in order to improve the methods of noise annoyance studies. These studies shape all the noise annoyance studies today. These researches are summarized and compared in this section.

Fields (1993) method

Fields (1993) conducted an elaborate study on the effect of personal and situational variables on noise annoyance in residential areas, using 136 social surveys which ask the respondents about their feelings about the environmental noise when they are at home. In the article, the findings on effects were classified as 'no important effect', 'an important effect which supports a hypothesis' or 'an important effect which is in the opposite direction to that hypothesized'. To determine whether an effect is important or not, the following six criteria were investigated, if any of them were met, the effect was labeled as 'important' (Fields, 1993):

- 3 dB: The difference in annoyance scores of the subgroups formed by the moderating variable is the equivalent of a 3-dB difference in noise exposure.

- Δ5%: There is at least a 5% difference between the percent annoyed in the subgroups of the moderating variable.

- 0.01r²: The moderating variable explains at least 1% of the variance in annoyance scores.

- p < 0.05: The relationship between the moderating variable and annoyance is statistically significant at p <0.05.

- 3/4g: 3/4 of sample groups support a hypothesis in an analysis that compares annoyance scores between moderating variable groups within subareas.

- Vb: There is an unqualified verbal assertion of a relation between annoyance and the moderating variable (Fields, 1993).

The quality of the findings were analyzed in three aspects; measurement and analysis methods, survey sizes and methodological weaknesses. 22 hypotheses were studied under seven headings, which were demographic characteristics, attitudes, individualized noise exposure, ambient noise, interviewing method, change in noise environment and annoyance at low noise levels. The hypotheses were tested according to percent of findings and responses supporting the stated hypothesis, supporting no important effect and supporting opposite hypothesis. The results were evaluated by

“balance of evidence”, checking if more than fifty percent of the findings and responses support the hypothesis or support having no important effect or support opposite hypothesis.

Fields et al. (1997) method

Fields et al. (1997) reported the guidelines produced by Community Response to Noise Team of ICBEN (The International Commission on the Biological Effects of Noise).

These guidelines were for reporting core information from community noise reaction surveys. In this study, over 360 acoustical and social surveys on environmental noise were examined. These survey studies differed from one another in many aspects, but all of them interviewed residents about their reactions to a noise source while living in their home. Noise exposure was measured or estimated and was compared to annoyance results. To improve comparability of these research results, guidelines for reporting core information from community noise reaction surveys were developed and minimal requirements were presented for three levels of publications. Level I is

“Limited” for conference papers, Level II is “Basic” for journal articles and Level III is “Extended” for research reports. This study was used to form the technical specification ISO/TS 15666:2003 “Acoustics - Assessment of noise annoyance by means of social and socio-acoustic surveys”.

Miedema and Oudshoorn (2001) method

Miedema and Oudshoorn (2001) worked on annoyance relationships with exposure descriptors day-night level, DNL and day-evening-night level, DENL, using analyses of the original data from various previous field surveys. A model was presented on the dispersion of noise annoyance as a function of noise exposure. The model was fitted with polynomial curve, for road, railway and aircraft traffic separately. Annoyance percentages were presented with cutoff points: “highly annoyed” (cutoff at 72 on a scale of 0–100), “annoyed” (cutoff at 50 on a scale of 0–100), and “a little annoyed”

(cutoff at 28 on a scale of 0–100). Confidence intervals were established.

Fields (2001) method

Fields et al. (2001) presented the work of Community Response to Noise Team of ICBEN (The International Commission on the Biological Effects of Noise). The work produced standardized general-purpose noise reaction questions for community noise surveys in nine languages. Standardized questions provided gathering of useful data to compare survey results from different cultures and countries. The goal was to design noise reaction questions with the following characteristics:

- Allow international comparisons between languages;

- Produce a reliable measure for general noise reaction in a residential environment;

- Provide transparent results;

- Provide a response scale compatible with statistical analysis;

- is likely to be used internationally;

- is suitable for all questionnaire methods.

After long years of research on existing surveys, wording of questions, answer scales and location of questions, two noise reaction questions were recommended. The 5-point verbal scale question was:

“Thinking about the last (…12 months or so…), when you are here at home, how much does noise from (…noise source…) bother, disturb, or annoy you; Extremely, Very, Moderately, Slightly or Not at all?''

The (0-10) point numeric scale question was:

“Next is a zero to ten opinion scale for how much (…source…) noise bothers, disturbs or annoys you when you are here at home. If you are not at all annoyed choose zero, if you are extremely annoyed choose ten, if you are somewhere in between choose a number between zero and ten. Thinking about the last (…12 months or so…), what number from zero to ten best shows how much you are bothered, disturbed, or annoyed by (…source…) noise?''

Figure 3.3 shows answer cards for recommend annoyance questions.

Figure 3.3 : Answer cards for recommend annoyance questions (Fields et al., 2001).

The paper also suggested guidelines to ensure the uniform administration of these questions:

- Ask all respondents both questions.

- Interviewers should not rephrase or explain questions, they should ask exactly as worded, to all respondents.

- Unless it conflicts with survey objectives, place the questions early in the questionnaire.

- Apply pretests and see if questions are perceived as repetitious. If that is the case, include appropriate instructions.

- Prepare written instructions for interviewers. (1) instruct interviewers to ask questions exactly as written, (2) train interviewers to respond to “I don't understand'' with methods that do not require paraphrasing the question, (3) urge respondents to choose between the offered answers, (4) encourage all residents to answer these questions (new residents can be instructed to answer about only their recent period of residence), (5) provide interviewers with instructions for respondents who find the questions to be repetitious.

One of the nine languages this study provided questions for was Turkish. The questions were as follows. The 5-point verbal scale question was:

“Yaklaşık son (…12 ayı…) düşündüğünüzde, (…gürültü kaynağından…) gelen gürültü, burada evinizdeyken sizi ne kadar rahatsız etmektedir?” ‘Feci şekilde’, ‘Çok’, Orta derecede’, ‘Hafifçe’, ‘Hiç değil’?

The (0-10) point numeric scale question was:

“Şimdi, burada evinizdeyken (…kaynak…) gürültüsünün sizi ne kadar rahatsız ettiğini ‘sıfır’ ile ‘on’ arasında sayılarla gösteren bir görüş (veya kanaat) ölçeği verilmektedir. Eğer hiç rahatsız değilseniz ‘sıfır’ı seçiniz, eğer feci şekilde rahatsız iseniz ‘on’u seçiniz, bunların arasında iseniz ‘sıfır’ ile ‘on’ arasında bir sayı seçiniz.

Yaklaşık son (…12 ayı…) düşünerek, (…kaynak…) gürültüsünden olan rahatsızlığınızı ‘sıfır’dan ‘on’a kadar hangi sayı en iyi gösterir?

This study (Fields et al., 2001) was used to form the technical specification ISO/TS 15666:2003 “Acoustics - Assessment of noise annoyance by means of social and socio-acoustic surveys”.

Klæboe et al. (2004) method

Klæboe et al. (2004) explored exposure–effect relationships between the road traffic noise at the most exposed facade and the residents’ reactions to road traffic noise. The study was based on five Norwegian socio-acoustic studies on 18 study areas from two cities (east Oslo in 1987, 1994 and 1996 and Drammen in 1998 and 1999) with almost 4000 total respondents. The survey questioned noise annoyance experienced right outside the apartment and when indoors. Although the wording of the questions were a little different form each other, they all asked firstly if people could hear the noise.

Exposure-effect relationships for all degrees of annoyance were estimated from ordinal logit models. Cumulative proportions were given for people experiencing different degrees of annoyance; does not hear, hears-not annoying, a little annoying, highly annoying; for different road traffic noise exposure values (Lden), for both indoor annoyance and annoyance when right outside apartment.

Discussion

Fields et al. (1997) method and Fields et al. (2001) method were both used to form the technical specification ISO/TS 15666: 2003 “Acoustics - Assessment of noise annoyance by means of social and socio-acoustic surveys”. These methods have been accepted worldwide and used ever since. Therefore, due to comparability, these methods should be used in this proposed methodology as well. Fields et al. (1997) method, Fields et al. (2001) method and therefore ISO/TS 15666 (2003) method will be used in this proposed methodology for information disclosure, standardized general-purpose noise reaction questions, 5-point verbal scale answers and (0-10) point numeric scale answers for socio-acoustic surveys.

Miedema and Oudshoorn (2001) method presented cutoff points for annoyance percentages: “highly annoyed” (cutoff at 72 on a scale of 0–100), “annoyed” (cutoff at 50 on a scale of 0–100), and “a little annoyed” (cutoff at 28 on a scale of 0–100).

This study is the leading study on annoyance percentage cutoff points and is accepted and used worldwide, therefore it will be used in this proposed methodology.