The site also contains a similar overview with precise figurers. The large energy variations in our inviroment (light, sound, touch, taste, smell, temperature etc) are compressed by our sensory system, in a subjective and complex mannar. Later, these measurements became called the Fletcher-Munson curves. A two times power change (3dB) is noticeable. But at high power, all frequencies tend to be heard at approx the same level.Īfter the telephone was invented, it was noticed that a ten times power change (10dB) was only heard as doubble or half as loud.
The loudness switch boosts the bass to compensate for our hearing at low level. This is the reason a loudness switch is put on most domestic sound equiptment. Reference for, threshold of hearing the smallest modulation, of atmospheric pressure.īy paying attention to this graph, it can be seen that at the threshold of hearing, our ears are approx 60dB (one million times) more sensitive at 2kHz than at 40Hz. Threshold of hearing, smallest modulation of atmospheric pressure.ĠdB SPL (Sound Pressure Level) 0.0002 dynes/cm² (20micro Pascals) at 2kHzĦ0 - 80dB SPL loud sound needing to speak loudly to be heard.Ĥ0 - 60dB SPL average noise level of the world we live and work in.Ģ0 - 40dB SPL quiet ambient background, will allow 60dB dynamic range.Ġ - 20dB SPL threshold of hearing, dependant on frequency. Our ears expand when it is quiet to hear detail and contract when it is loud.ģdB = x 2 power change we only hear as a bit louder.ĦdB = x 4 power change we only hear as a bit louder again.ġ0dB = x 10 power change we only hear as double as loud.ĭifference between 100 - 200 Watt sound system, is minimal ( 3dB)ĭifference between 100 - 1,000 Watt sound system, is twice as loud ( 10dB) 0dB SPL (Sound Pressure Level) 3dB 6dB then to next 10dB.Īre used for specifications of speaker crossovers and EQ filters.Įach (6dB / octave) step is described as an 'order'. No need for calculator.Īll dB rounded to nearest 3dB step. With pensil and paper continue to practice. Hundreds of years ago, writing was done with a quill (ducks feather) dipped in ink.ĭoing math with large numbers was time consuming and painfull for ducks.ġ,000,000 has 6 zeros and can be abreviated as (10 6) or (60dB) Lograthims are a simple and literal way of writing large numbers. Octave is also used to describe double or half the frequency (ratio 1:2) (tone, tone, tone, semi-tone) (tone, tone, tone, semi-tone) The division between the notes is based on the 12th root of 2Įach single adjacent note is called a Semi-tone.Įach second alternate note is called a Tone.Ĩ (Octave) of the 12 notes can be used to make a scale, as 2 tetra-chordsĮg. Notation is based on 12 notes, between each doubling of the frequency (octave)īetween (A 110 Hz - A 220 Hz) are 12 notesīetween (A 220 Hz - A 440 Hz) are 12 notes and so on
The highest notes depending on the instrument is approx 2k HzĪbove these highest notes are the harmonics. The lowest note on a double bass or bass guitar is open E (42Hz) Human hearing is approx 30 Hz - 16k Hz and most sensitive between 2k - 3k Hz Sound frequency measurement is 20 Hz - 20k Hz (20 - 20,000 Hz) (cps) is changed to Hz in honour of the physicist Hertz. The number of vibrations per second is called (cps) 'cycles per second' Sound is vibrating air, which our ears can hear
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