ConverterHub

Phon to Sone Calculator

Shows how loud a phon level is on the sone scale, where doubling means twice as loud.

Result

8.00 sone

How it is calculated

The loudness level in phon is converted with two formulas, depending on the range. At 40 phon or above: sone = 2(phon − 40) / 10, so 40 phon is exactly 1 sone and every extra 10 phon doubles the loudness in sones. Below 40 phon the tool uses sone = (phon / 40)2.642, a curve that falls towards zero for very quiet sounds. The two branches meet at 1 sone. Negative values give no result, and the answer is shown with two decimals. The input must already be a loudness level in phon, not a plain decibel reading.

Worked example

A sound has a loudness level of 70 phon. This is above 40, so the first formula applies: (70 − 40) / 10 = 3, and 23 = 8. The result is 8.00 sone. It sounds eight times as loud as a 40-phon sound. For comparison, a quiet 20-phon sound uses the second formula: (20 / 40)2.642 ≈ 0.16 sone.

Try this example →

Common mistakes

  • Entering decibels (dB SPL) instead of phon. Phon accounts for how the ear hears different frequencies; a dB value at 100 Hz and at 1 kHz are not the same loudness.
  • Expecting 10 phon more to mean 10 sone more. Every 10 phon doubles the sone value, so the growth is exponential, not linear.
  • Applying the 2(phon − 40)/10 rule below 40 phon. Below that point the tool uses a different curve, so the simple doubling rule does not hold.
  • Entering a negative phon value. The tool returns no result for it, because the scale starts at 0 phon, which gives 0.00 sone.
  • Comparing a sone figure with a phon figure on one scale. They are different units and cannot be added or compared directly.

About this calculator

Phon measures perceived loudness as the sound pressure level, in dB, of a 1 kHz reference tone that sounds equally loud (accounting for how the ear's sensitivity varies by frequency), while sone is built so that a doubling of the sone value means a doubling of perceived loudness — a property phon doesn't have. Above 40 phon, the two relate by sone = 2^((phon − 40)/10), with 40 phon fixed at exactly 1 sone.

Acousticians and audio engineers use sone when a linear “twice as loud” scale matters more than a raw decibel-style figure, and manufacturers of appliances, HVAC units, and power tools often publish noise ratings in sone precisely because it maps more directly onto how loud a product feels to a listener.

Was this helpful?

You can pick up to 3 reactions.

Comments

  • Be the first to comment.

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators