The sensitivity of the human ear changes as a function of frequency, as shown in the equal-loudness graph. Each line on this graph shows the SPL required for frequencies to be perceived as equally loud, and different curves pertain to different sound pressure levels.

An equal-loudness contour is a measure of sound pressure level, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. [1] The unit of measurement for loudness levels is the phon and is arrived at by reference to equal-loudness contours.

Mar 16, 2025 · The graph in Figure \(\PageIndex{4}\) should be referenced to solve this example. To find the loudness of a given sound, you must know its frequency and intensity level, locate that point on the square grid, and then interpolate between loudness curves to …

Frequency is plotted along the x-axis and sound level is plotted on the y-axis. Each curve on the graph represents sounds with equal perceived loudness. The bottom curve represents all sounds at the threshold of human hearing. Points along this trace are barely perceptible for most people.

Normal equal-level-contours are often referred to as equal-loudness-curves and provide technical data to establish the perceived loudness levels of humans with 'normal' hearing aged between 18 and 25 years of age.

Three example curves from the equal loudness curves are shown below, corresponding to very soft, midrange and very loud sounds. Examination of these three curves makes it evident that there is considerable difference between the ear's response at different sound levels.

Nov 8, 2024 · On the axes below, sketch an equal loudness curve showing the normal response of a healthy ear. Annotate the frequency axis with an appropriate scale. Answer: Step 1: Recall the frequency range of human hearing. Step 2: Recall how to plot a logarithmic scale.

May 15, 2021 · Any fundamentals of audio production or acoustics course will include a discussion on the Fletcher-Munson Equal Loudness Contours. It is important for audio engineers to understand the implications of this graphic representation in terms of mixing, mastering and how listeners will perceive the music they produce.

Jan 28, 2023 · The Fletcher-Munson curves are a series of plots on an X/Y graph, where X is frequency and Y is loudness in dB SPL. At lower volumes, midrange frequencies appear to be the loudest or most noticeable, while lows and highs take a backseat.

May 12, 2024 · An interactive set of equal loudness contours based on ISO Standard 226:2023-03.