Sone Meaning
The unit for measuring the quantity of sound pressure we perceive from the loud music is the Sone.
While enjoying a late-night DJ party, we love to hear loud music and that music creates a lot of pressure on our ears. This loudness has some measurement and that measurements hold a unit with itself. The unit for the same is Sone. Sone is the comprehensive unit of loudness.
On this page, we will learn about sones, the meaning of sone, and the types of sones in detail.
Meaning of Sone
Sones is a subjective unit of loudness. For an average listener, one sone equal to the loudness of a 1000-hertz sound that has an intensity of 40 dB, i.e., above the listener's own threshold ability of hearing
So, basically, sone is a unit of loudness. Loudness is a subjective characteristic of a sound, as compared to the sound pressure level in dB, which is objective and easily measurable. Consequently, the sone scale of loudness is dependent on data achieved from subjects who were asked to distinguish among the loudness of pure tones and noise. One sone is arbitrarily set equal to the loudness of a 1,000-Hz tone at a sound level of 40 decibel above the standard normal or the reference level, i.e., the minimum audible threshold. A sound with a loudness of 3 sones is one that listeners perceive to be three times as loud as the reference sound.
One Sone
According to the definition given by Steven, a loudness of 1 sone is equal to 40 phons or a 1 kHz. The phon scale closely aligns with decibel, not with loudness, so the sone and phon scales are not proportionally related. Rather, the loudness in sones is, at least more of a power-law function of the signal intensity, with an exponent of 0.3, with this exponential value, every 10 phons (or 10 dB at 1 kHz) increase produces almost double of the loudness in sones.
Sone Definition And Conversions
Below is the table for the sone and phon conversion:
Sones Meaning
From the above table, we see that at frequencies other than 1 kHz, the loudness level in phons is calibrated according to the frequency response of human hearing ability through the set of equal-loudness contours, and then the loudness level in phons is matched to the loudness in sones through the same power law.
For the power law, loudness N in sones is LN, which is greater than 40 phons.
Where,
\[N=\left ( 10^{\frac{L_{N}-40}{10}} \right )^{0.30103} \approx 2^{\frac{L_{N}-40}{10}}\] ….(1)
LN = 40 + 10 Log2 (N)....(2)
Here, the loudness level LN in phons for N is greater than 1 sone.
Sometimes, corrections are required at lower levels, near the threshold ability of hearing.
The formulas mentioned in equations (1) and (2) are valid for single-frequency sine waves or narrowband signals only. However, for multi-component or broadband signals, a more elaborative or expanded loudness model is required, accounting for critical bands.
To have a piece of precise information, a measurement in sones must be described in terms of the suffix G, where ‘G’ means that the loudness value is calculated from frequency groups, and by one of the two suffixes D, i.e., for direct field/free field or R, i.e., for room field/diffuse field.
Points To Note:
Sones are not decibels or volume or any other measuring units, it is actually a way to determine how sound is sensed. They are linear measurements similar to inches. Doubling the sone value means doubling the loudness (i.e. one to two, two to four is doubling the sound level in twice magnitude). Your 3 sone fan will be more than three times as noisy as a 0.9 sone fan.
One sone is equal to the sound of a quiet refrigerator in a quiet kitchen. Typically, the sone level is measured at the maximum speed of cubic feet per minute; however, some newly-launched products are also being tested at normal CFM settings to assure consumers with low sound level information.
FAQs on Sone
1. What is a sone and how is it used to measure loudness?
A sone is a unit used to measure the perceived loudness of a sound, meaning how loud a sound feels to the human ear. It provides a linear scale where a sound of 2 sones is perceived as twice as loud as a sound of 1 sone. The reference point is defined as 1 sone being equivalent to the loudness of a pure 1000 Hz tone at a sound level of 40 decibels above a listener's hearing threshold.
2. How does a sone differ from a decibel (dB)?
The main difference lies in what they measure:
- Sone: Measures subjective loudness, which is how a person perceives a sound's volume. It is a linear scale, so doubling the sone value means the sound is perceived as twice as loud.
- Decibel (dB): Measures objective sound pressure level, which is a physical property of the sound wave. It is a logarithmic scale, so a small increase in dB represents a large increase in sound intensity.
Essentially, dB measures the physical energy of a sound, while sone measures the psychological sensation of its loudness.
3. What are some real-world examples of sone ratings?
Sone ratings are commonly used for appliances where noise level is a key feature for consumers. Here are some typical examples:
- A quiet refrigerator in a silent room is about 1 sone.
- A modern, quiet bathroom exhaust fan might be rated between 0.5 to 1.5 sones.
- A normal conversation is approximately 4 sones.
- An older or louder kitchen range hood could be 5 sones or more at its highest setting.
4. How are sones and phons related in the measurement of loudness?
Both sones and phons are units of perceived loudness, but they have a specific relationship. A phon is a unit of loudness level that equates the loudness of any sound to the decibel level of a 1000 Hz tone that sounds equally loud. The sone scale is then derived from the phon scale to be linear. As a rule of thumb, an increase of 10 phons is perceived as a doubling of loudness, which corresponds to a doubling of the sone value. For example, 40 phons equals 1 sone, while 50 phons equals approximately 2 sones.
5. Why was the sone scale created when the decibel scale already existed?
The sone scale was created to address a key limitation of the decibel (dB) scale. While decibels accurately measure the physical intensity of sound, they do not directly correspond to how the human brain perceives loudness. The human ear is not equally sensitive to all frequencies. The sone scale was developed to be a psychological or subjective scale, providing a more intuitive and linear measurement that reflects how an average person actually experiences and compares the loudness of different sounds in a real-world environment.
6. How does doubling the sone value affect the perceived loudness of a sound?
The sone scale is designed to be linear in its relationship to perceived loudness. This means that doubling the sone value means the sound is perceived by the human ear as being exactly twice as loud. For instance, a device rated at 4 sones will sound two times as loud as a device rated at 2 sones. This simple, direct relationship makes it much easier for consumers to understand and compare the noise levels of products like fans or air purifiers.
7. Does the frequency of a sound affect its measurement in sones?
Yes, frequency is a critical factor in determining a sound's sone value. The human ear is most sensitive to frequencies in the mid-range (around 1-4 kHz) and less sensitive to very low or very high frequencies. The calculation of sones takes this into account using equal-loudness contours. Therefore, two sounds with the exact same decibel level but different frequencies will have different sone values because they are perceived as having different loudnesses. A 70 dB sound at 1000 Hz will have a much higher sone value than a 70 dB sound at 50 Hz.
