No one needs the sone numbers to know which sound is perceived loudest. All of the following sounds are rated at 85 decibels. High frequency sounds are usually over 2000 Hertz like whistles and finger nails on a chalkboard.Īnother example of the perceived loudness of sound. Low frequency sounds are under 500 Hertz such as ocean waves and avalanches. Although the decibel value is the same, the perceived loudness is much different because of the frequency.įrequency is a measurement of the total number of sound waves produced in one second. For example: a 10 decibel sound (tone) at 50 Hertz is inaudible to humans, but the same 10 decibel tone at 5000 Hertz is clearly audible. The lower limit of the human hearing threshold is frequency dependent producing different sone hearing values at different frequencies. Sones represent perceived loudness of sound which includes sound wave frequency as measured in Hertz. Along with applicable graphs, charts, and examples.ĭecibels represent the amplitude of a sound. The following YouTube video produced by Siemens will help introduce you to loudness and sones. Sone values are different then decibel measurements because they take into account the frequency and level dependency of human hearing. The article also provides more details about sones. This chart from Wikipedia shows the comparison of sones, pascals, and decibels for a few chosen sounds.

Sones Chart – Sones, Pascals, Decibels (dB) A sound with a loudness of four sones is one that listeners perceive to be four times as loud as the reference sound. One sone is arbitrarily set equal to the loudness of a 1,000- hertz tone at a sound level of 40 decibels above the standard reference level (i.e., the minimum audible threshold). Consequently, the sone scale of loudness is based on data obtained from subjects who were asked to judge the loudness of pure tones and noise. Loudness is a subjective characteristic of a sound (as opposed to the sound-pressure level in decibels, which is objective and directly measurable). The Encyclopedia Britannica describes sone as follows: Raise the same 20 decibel whisper to 500 Hertz and it becomes audible. Meaning our perception of sound level is related to the frequency of the sound wave.įor instance, a 20 decibel whisper delivered at 100 Hertz (frequency measurement) cannot be heard by the human ear. Most people hear high frequency sound waves better than lower frequencies. The human test subjects used to develop the sones rating system were asked to describe how loud a sound felt.Ī sone rating for sounds may be more useful because humans sense higher and lower sound wave frequencies differently. It is a system to tell how loud a sound feels to humans. Sones are not a physical measurement like decibels. The sones rating system is a way to measure or express perceived loudness. For every 3 decibel increase or decrease, you are adding or dropping 50% of the sound pressure levels your ears are exposed to. A simplified explanation is the 3 Decibel Rule. In some ways sone noise levels are easier to understand then decibel levels.ĭecibel levels use a logarithmic scale like the Richter earthquake scale. 2 sones are twice as loud as 1 sone and 4 sones are twice as loud as 2 sones. This means that doubling the number of sones doubles the noise level. If you know what a sone represents in the real world (See chart below.), you will be better able to know what the machine will sound like. But some electrical or mechanical equipment like range hoods and bathroom fans give sound value in sones. Most sound levels for equipment such as lawn mowers or compressors are given in decibels. Not very helpful? Please read on for real information that you can use when confronted with noise levels expressed in sones. Phon: a unit of the perceived loudness of sounds. Sone: a unit of subjective loudness, equal to 40 phons. Here is the Concise Oxford Dictionary definition. But when a measurement of noise level is expressed in sones, we might be a little confused. Most people have at least a rough idea of what a decibel is.

Equal loudness spl hl decibel scale