Standard Practice for Determination of Odor and Taste Thresholds By a Forced－ Choice Ascending Concentration Series Method of Limits ${}^1$${}^1$^(1){ }^{1}
通过强制选择上升浓度限值系列方法测定气味和味觉阈值的标准实践 ${}^1$${}^1$^(1){ }^{1}

The obtaining of odor and taste thresholds requires the sensory responses of a selected group of individuals called panelists．These thresholds may be determined in order to note the effect of various added substances on the odor and taste of a medium．They may also be determined in order to characterize and compare the odor or taste sensitivity of individuals or groups．
获取气味和味觉阈值需要一组被选中的个体，即品评员的感觉反应。这些阈值可以用来确定各种添加物质对介质气味和味觉的影响。它们也可以用来表征和比较个体或群体的气味或味觉敏感性。

It is recognized that precise threshold values for a given substance do not exist in the same sense that values of vapor pressure exist．The ability to detect a substance by odor or taste is influenced by physiological factors and criteria used in producing a response by the panelist．The parameters of sample presentation introduce further variations．Thus，the flowrate of a gaseous，odorous sample has an influence on the detectability of an odor．However，a concentration range exists below which the odor or taste of a substance will not be detectable under any practical circumstances，and above which individuals with a normal sense of smell or taste would readily detect the presence of the substance．
人们认识到，对于某种物质，精确的阈值并不像蒸汽压值那样存在。通过气味或味觉检测物质的能力受生理因素和品评员产生反应所使用的标准的影响。样品呈现的参数引入了进一步的变异。因此，气态气味样品的流速会影响气味的可检测性。然而，存在一个浓度范围，在该范围以下，在任何实际情况下，物质的气味或味觉都不会被检测到，而在该范围以上，具有正常嗅觉或味觉的个体会很容易检测到物质的存在

The threshold determined by this practice is not the conventional group threshold（the stimulus level detectable with a probability of 0.5 by $50\mathrm{\%}$$50\mathrm{\%}$50%50 \% of the population）as obtained by Practice E1432，but rather a best estimate not far therefrom．The bias of the estimate depends on the concentration scale steps chosen and on the degree to which each panelist＇s threshold is centered within the range of concentrations he or she receives．The user also needs to keep in mind the very large degree of random error associated with estimating the probability of detection from only 50 to 1003 －AFC presentations．
本方法确定的阈值并非传统群体阈值（即以 0.5 的概率被 $50\mathrm{\%}$$50\mathrm{\%}$50%50 \% 人群检测到的刺激水平），而是与此接近的最佳估计值。估计的偏差取决于所选的浓度标度步长以及每位评价员在其接收的浓度范围内阈值的中心程度。用户还需要牢记，仅从 50 到 1003 次-AFC 呈现中估计检测概率与非常大的随机误差相关。

1．1 This practice describes a rapid test for determining sensory thresholds of any substance in any medium．
1．1 本方法描述了一种快速测试方法，用于确定任何介质中任何物质的感官阈值。

1．2 It prescribes an overall design of sample preparation and a procedure for calculating the results．
1．2 它规定了样品制备的整体设计以及计算结果的程序。

1．3 The threshold may be characterized as being either（a） only detection（awareness）that a very small amount of added substance is present but not necessarily recognizable，or（b） recognition of the nature of the added substance．
1．3 阈值可以被描述为要么（a）仅能检测到（意识到）添加物质的极少量存在，但不一定能够识别，要么（b）能够识别添加物质的性质。

1．4 The medium may be a gas，such as air，a liquid，such as water or some beverage，or a solid form of matter．The medium may be odorless or tasteless，or may exhibit a characteristic odor or taste per se．
1．4 媒介可以是气体，如空气，液体，如水或某些饮料，或物质固体形式。媒介可以是无味或无味，或本身具有特征性气味或味道。

1．5 This practice describes the use of a multiple forced－ choice sample presentation method in an ascending concentra－ tion series，similar to the method of limits．
1．5 本实践描述了在递增浓度系列中使用多重强迫选择样本呈现方法，类似于极限方法。

1．6 Physical methods of sample presentation for threshold determination are not a part of this practice，and will depend on the physical state，size，shape，availability，and other properties of the samples．
1．6 用于阈值确定的样本呈现的物理方法不是本实践的一部分，并将取决于样品的物理状态、大小、形状、可用性和其他特性

1．7 It is recognized that the degree of training received by a panel with a particular substance may have a profound influ－ ence on the threshold obtained with that substance（1）．${}^2$${}^2$^(2){ }^{2}
1．7 认识到，一个特定物质的专业小组所接受的培训程度可能对该物质所获得的阈值有深远影响（1）． ${}^2$${}^2$^(2){ }^{2}

1.8 Thresholds determined by using one physical method of presentation are not necessarily equivalent to values obtained by another method.
1.8 使用一种物理呈现方法确定的阈值不一定等同于通过另一种方法获得的值。

2.1 ASTM Standards: ${}^3$${}^3$^(3){ }^{3}  2.1 ASTM 标准： ${}^3$${}^3$^(3){ }^{3}

D1292 Test Method for Odor in Water
D1292 水中气味测试方法
E544 Practices for Referencing Suprathreshold Odor Intensity
E544 参考超阈值气味强度实践
E1432 Practice for Defining and Calculating Individual and Group Sensory Thresholds from Forced-Choice Data Sets of Intermediate Size
E1432 从中等规模强迫选择数据集定义和计算个体和群体感官阈值实践
2.2 CEN Standards: ${}^4$${}^4$^(4){ }^{4}
2.2 CEN 标准： ${}^4$${}^4$^(4){ }^{4}

EN 13725 Air Quality—Determination of Odour Concentration Using Dynamic Dilution Olfactometry
EN 13725 空气质量—使用动态稀释嗅闻法测定臭气浓度
2.3 ISO Standards: ${}^5$${}^5$^(5){ }^{5}
2.3 ISO 标准： ${}^5$${}^5$^(5){ }^{5}

ISO 13301 Sensory Analysis-Methodology-General Guidance for Measuring Odour, Flavour and Taste Detection Thresholds by a Three Alternative Forced Choice (3-AFC) Procedure
ISO 13301 感官分析—方法学—通过三替代强制选择（3-AFC）程序测量臭味、风味和味觉检测阈值的一般指南

3.1 Definitions:  3.1 定义：
3.1.1 sample-a material in any form that may or may not exhibit an odor or taste, depending on the amount of odorous or sapid components that it may contain.
3.1.1 样品-a 任何形式可能或不可能表现出气味或味道的物质，取决于其中含有的有味或可尝成分的量。
3.1.2 medium-any material used to dissolve, disperse, or sorb odorous or sapid material whose threshold is to be measured.
3.1.2 介质-用于溶解、分散或吸附待测气味或可尝物质的任何材料。
3.1.3 blank sample-a quantity of the medium containing no added odorous or sapid material.
3.1.3 空白样品-含有未添加气味或可尝物质的介质的一定量。
3.1.4 test sample-the medium to which an odorous or sapid material has been added at a known concentration.
3.1.4 测试样品-将具有气味的或味道的物质添加到已知浓度的介质中。
3.1.5 detection threshold-the lowest concentration of a substance in a medium relating to the lowest physical intensity at which a stimulus is detected as determined by the bestestimate criterion.
3.1.5 检测阈值-介质中物质的最低浓度，与刺激被检测到的最低物理强度相关，该强度由最佳估计标准确定。
3.1.6 recognition threshold-the lowest concentration of a substance in a medium relating to the lowest physical intensity at which a stimulus is recognized as determined by the best-estimate criterion.
3.1.6 识别阈值-介质中物质的最低浓度，与刺激被识别的最低物理强度相关，该强度由最佳估计标准确定。
3.1.7 best-estimate criterion-an interpolated concentration value, but not necessarily the concentration value that was actually presented. In this practice it is the geometric mean of the last missed concentration and the next (adjacent) higher concentration.
3.1.7 最佳估计标准-一个插值浓度值，但不一定是实际呈现的浓度值。在本实践中，它是最后一次错过的浓度值和下一个（相邻）较高浓度值的几何平均值。
3.1.8 panelists-individuals whose odor or taste thresholds are being evaluated, or who are utilized to determine the odor or taste threshold of the substance of interest.
3.1.8 评价人员-其气味或味觉阈值正在被评估的人员，或用于确定目标物质的气味或味觉阈值的人员。

3.1.9 ascending scale of concentrations-a series of increasing concentrations of an odorous or sapid substance in a chosen medium.
3.1.9 升序浓度标度-在选定介质中一系列递增浓度的有臭味或味觉的物质。
3.1.10 scale steps-discrete concentration levels of a substance in a medium, with concentrations increased by the same factor per step throughout the scale.
3.1.10 标度步长-介质中物质的离散浓度水平，在整个标度中每一步浓度增加相同的因子。
3.1.11 3-alternative forced choice (3-AFC) presentation-a set consisting of one test sample and two blank samples (as applied to this practice).
3.1.11 三选一强制选择（3-AFC）呈现-一个由一个测试样品和两个空白样品组成的集合（适用于本标准）。
3.1.12 geometric mean-the $n$$n$nnth root of the product of terms. In this method, the terms are concentration values.
3.1.12 几何平均值 - 乘积项的 $n$$n$nn 次方根。在此方法中，项为浓度值。

4.1 A series of test samples is prepared by dispersing the substance whose threshold is to be determined in the medium of interest. This concentration scale should increase in geometric increments so that any two adjacent concentration steps are separated by a constant factor. At each concentration step, two blank samples consisting of the medium only are made available to the panelist. The blank and test samples are encoded so that there is no visual, audible, tactile, or thermal difference between the samples other than code designators (2).
4.1 通过将待测定阈值的物质分散在感兴趣的介质中制备一系列测试样品。该浓度标度应以几何增量增加，以便任何两个相邻的浓度步骤之间都有一个恒定的因子。在每个浓度步骤中，提供两个空白样品，其中只包含介质。空白样品和测试样品进行编码，以便除了代码标识符外（2），样品之间没有视觉、听觉、触觉或热觉的差异。
4.2 The panelist starts at the lowest concentration step, which should be two or three concentration steps below the estimated threshold. Each sample within the set of three is compared with the other two.
4.2 评审员从最低浓度步骤开始，该步骤应低于估计阈值两个或三个浓度步骤。在三个样品集中，每个样品都与另外两个进行比较。
4.3 The panelist indicates which of the three samples is different from the other two. A choice must be made, even if no difference is noted, so that all data can be utilized.
4.3 评价员指出三个样品中哪一个与其他两个不同。必须做出选择，即使没有注意到差异，以便所有数据都能被利用。
4.4 Individual best-estimate values of threshold are derived from the pattern of correct/incorrect responses produced separately by each panelist. Group thresholds are derived by geometrical averaging of the individual best-estimate thresholds.
4.4 单个最佳估计阈值是从每个评价员分别产生的正确/错误响应模式中得出的。组阈值是通过单个最佳估计阈值几何平均得出的。

5.1 Sensory thresholds are used to determine the potential of substances at low concentrations to impart odor, taste, skinfeel, etc. to some form of matter.
5.1 感官阈值用于确定物质在低浓度下对某种物质产生气味、味道、触感等的潜在能力。
5.2 Thresholds are used, for example, in setting limits for air pollution, in noise abatement, in water treatment, and in food systems.
5.2 阈值用于设定空气污染限值、噪声减弱、水处理和食品系统中的限制等。
5.3 Thresholds are used to characterize and compare the sensitivity of individual or groups to given stimuli, for example, in medicine, in ethnic studies, and in the study of animal species.
5.3 阈值用于表征和比较个人或群体对给定刺激的敏感性，例如在医学、民族研究和动物物种研究中。

6.1 The concentration levels of the test substance in a medium should begin well below the level at which the most sensitive panelist is able to detect or recognize the added substance, and end at (or above) the concentration at which all panelists give a correct response.
6.1 测试物质在介质中的浓度水平应从最敏感的评审员能够检测或识别添加物质的水平以下开始，并在（或高于）所有评审员给出正确反应的浓度处结束。
6.2 The increase in concentration of the test substance per scale step should be by a constant factor. It is desirable to
6.2 每个刻度步长，测试物质的浓度增加应为常数。最好
obtain a scale step factor that will allow the correct responses of a group of nine panelists to distribute over three to four concentration steps (see Appendix X1-Appendix X3). This will allow more accuracy in determining the group threshold value based on the geometric mean of the individual panelists.
获得一个标度步长因子，使九位评审员的正确反应能够分布在三到四个浓度等级（参见附录 X1-附录 X3）。这将允许基于个人评审员的几何平均值来确定组阈值时具有更高的准确性。
6.3 Good judgment is required by the person in charge in order to determine the appropriate scale step range for a particular substance. This might involve the preparation of an approximate threshold concentration of the odorous or sapid substance in the medium of choice. The concentration of the substance may be increased two to three times for odorants or 1.5 to 2.5 times for sapid substances depending on how the perceived intensity of odor or taste varies with the concentration of the substance providing the sensory response. For example, if $x$$x$xx represents an approximate odor threshold concentration, then a series of concentration steps would appear as follows if a step factor of " 3 " were used:
6.3 负责人需要良好的判断力，才能确定特定物质的适当标度步长范围。这可能涉及在选择的介质中制备具有气味的或味道的物质的近似阈值浓度。物质的浓度可能根据感知的气味或味道强度如何随提供感觉反应的物质浓度而变化，而增加两到三倍（对于气味物质）或 1.5 到 2.5 倍（对于味道物质）。例如，如果 $x$$x$xx 代表近似气味阈值浓度，那么如果使用“3”作为步长因子，一系列浓度步长将如下所示：

6.4 In actual practice, the various concentrations are obtained by starting at the highest concentration and diluting three times per step, thus providing a series of dilution factors, " $V_i$$V_i$V_(i)V_{i} " being the initial volume:
6.4 在实际操作中，各种浓度是通过从最高浓度开始，每步稀释三次获得的，从而提供一系列稀释因子，“ $V_i$$V_i$V_(i)V_{i} ”为初始体积：

6.5 At each selected concentration or dilution, a 3-AFC sample set consisting of one test and two blank samples is presented to panelists in indistinguishable fashion (3). It is desirable to have all samples prepared and ready for judging before the evaluation session begins. (Reference (2) contains sound practices for coding the samples, rotating the positions of these test and blank samples as the test proceeds, etc.)
6.5 在每个选定的浓度或稀释步骤中，向评审员提供一套 3-AFC 样品，包括一个测试样品和两个空白样品，以无法区分的方式呈现（3）。最好在评估会议开始之前准备好所有样品，以便进行评判。（参考文献（2）包含了关于样品编码、在测试过程中旋转这些测试和空白样品位置等方面的良好实践。）
6.6 If the samples are arranged in a left-center-right, or an above-center-below order, care must be taken that the test sample is presented in one third of the presentations in the left (top) position, one third in the center position, and one third in the right (bottom) position to eliminate positional bias.
6.6 如果样品排列在左-中-右或上-中-下的顺序中，必须注意测试样品在三分之一的情况下出现在左（上）位置，三分之一出现在中心位置，三分之一出现在右（下）位置，以消除位置偏差。
6.7 If only one sample at a time is available, the test and blank samples may be presented one after another in units of three presentations, with the test sample being randomized to be the first, the second, and the third, and requesting the response after all three samples in the set have been presented. Better results, however, are obtained if the test and the two blank samples are available for a direct comparison, so that the panelist may sniff or taste back and forth at ease until a decision is reached.
6.7 如果一次只有一个样品可用，测试样品和空白样品可以一个接一个地以三组呈现，测试样品随机地作为第一、第二和第三个样品，并在所有三组样品呈现后要求做出反应。然而，如果测试样品和两个空白样品可用于直接比较，那么结果会更好，这样评审员可以轻松地来回闻或品尝，直到做出决定。

7.1 The panelist begins judging with that set which contains the test sample with the lowest concentration (highest dilution) of the odorous or sapid substance, takes the time needed to make a selection, and proceeds systematically toward the higher concentrations.
7.1 评审员从含有最低浓度（最高稀释度）的气味或味道物质的样品组开始判断，需要时间做出选择，然后系统地朝向较高浓度进行。
7.2 Within each set, the panelist indicates that sample which is different from the two others (detection threshold) or which exhibits a recognizable odor or taste of the substance (recognition threshold). If the panelist cannot readily discriminate, a guess must be made so that all data may be utilized.
7.2 在每个样品组中，评审员指出与其他两个不同的样品（检测阈值）或表现出可识别的气味或味道的物质（识别阈值）。如果评审员不能轻易区分，必须猜测，以便所有数据都能被利用。
7.3 The judgments are completed when the panelist either (1) completes the evaluation of all sets of the scale, or (2) reaches a set wherein the test sample is correctly identified, then continues to choose correctly in higher concentration test sample sets.
7.3 当评价员完成所有浓度梯度的评价，或达到一个正确识别测试样本的浓度梯度，并继续在更高浓度的测试样本梯度中正确选择时，判断即完成。

8.1 The series of each panelist’s judgments may be expressed by writing a sequence containing (0) for an incorrect choice or $(+)$$(+)$(+)(+) for a correct choice arranged in the order of judgments of ascending concentrations of the added substance.
8.1 每位评价员的一系列判断可以通过按升序浓度排列的（0）表示错误选择或 $(+)$$(+)$(+)(+) 表示正确选择来书写一个序列。
8.2 If the concentration range has been correctly selected, all panelists should judge correctly within the range of concentration steps provided. Thus, the representation of the panelists’ judgments as in 8.1 should terminate with two or more consecutive plusses (+).
8.2 如果浓度范围选择正确，所有评价员应在提供的浓度梯度范围内正确判断。因此，按 8.1 表示的评价员的判断应终止于两个或多个连续的加号（+）。
8.3 Because there is a finite probability that a correct answer will occur by chance alone, it is important that a panelist continues to take the test until there is no doubt by that person of the correctness of the choice.
8.3 由于正确答案有可能仅凭偶然出现，因此重要的是，评审员应继续进行测试，直到该人对选择的正确性不再有任何疑问。
8.4 The best-estimate threshold concentration for the panelist is then the geometric mean of that concentration at which the last miss ( 0 ) occurred and the next higher concentration designated by a (+).
8.4 评审员的最佳估计阈值浓度是最后一次出现错误（0）时的浓度与下一个更高浓度（标记为+）的几何平均值。
8.5 The panel threshold is the geometric mean of the best-estimate thresholds of the individual panelists. If a more accurate threshold value of an individual panelist is desired, it may be obtained by calculating the geometric mean of the best-estimate threshold of all series administered to that person.
8.5 面板阈值是各个评审员最佳估计阈值的几何平均值。如果需要获得某个评审员更精确的阈值，可以通过计算该评审员所有系列测试的最佳估计阈值的几何平均值来获得。

9.1 Successful completion of the foregoing procedure provides either the detection or recognition threshold of the substance in the medium of interest in accordance with this practice.
9.1 成功完成上述程序可提供本实践规定的介质中物质的检测或识别阈值。
9.2 The threshold value is in concentration or dilution units appropriate for the substance tested (4).
阈值以适用于所测物质的浓度或稀释单位表示（4）。
9.3 For enhanced understanding of the threshold results, the following information is recommended:
9.3 为了更好地理解阈值结果，建议提供以下信息：

Threshold of:  阈值为：
Procedure: ASTM Practice E679 (Rapid Method)
步骤：ASTM 实践 E679（快速方法）
Presentation:  展示：
Number of scale steps:
刻度级数：
Dilution factor per step:
每一步的稀释因子
Temperature of samples:  样品的温度：
Panelist selection:  评审员的选择：
Number of times test given:
测试进行的次数：
Type of threshold (detection or recognition):
阈值的类型（检测或识别）：
Best-estimate threshold:
最佳估计阈值：
Individual:  单个：
Panel:  面板：
9.4 Refer to Appendix X1-Appendix X3 for examples of the calculations and reporting requirements.
9.4 参考附录 X1-附录 X3 以获取计算示例和报告要求的说明。

10.1 Because sensory threshold values are functions of sample presentation variables and of individual sensitivities, interlaboratory tests cannot be interpreted statistically in the
10.1 由于感官阈值是样品呈现变量和个人敏感性的函数，因此实验室间测试不能进行统计解释