The noticeable tones in background noises can annoy and disturb human listeners. The noise community has been developing methods to quantify perception of tones and lately trying to propose new tone guidelines to regulate the maximum level of tones in noise. Prior to proposing guidelines, the reliability of existing tone quantification methods should be examined. Thus, this paper investigates uncertainty of the tone quantifying methods from ANSI or ISO standards including Tonal Audibility, Prominence Ratio, and Tone-to-Noise Ratio. This study will discuss major causes of uncertainty in measuring the tones from using the methods. It will cover definitions of tones in each method, how these metrics separate tones and broadband noises, and how they analyze signals in time and frequency domains. Lastly, this paper will also investigate effects of room modes on the measured tonality in indoor environments. The variances of the measured tonality across measurement positions for the assorted metrics will be pres...