Audio BasicMy name is David,I am from Republic of Serbia, based in Belgrade. I am student of Audio and VideoTechnology in my city.
Audio BasicThis is the lesson for week 1. I will be teaching you aboutAudio Basics, in fact- this presentation is especially about“Frequency”
Audio BasicBasic parameters in audio are: Propagation Amplitude Frequency Timbre
Frequency…is the number of occurrences of a repeating event per unit time. In audio engineeringif you now know the time, you know the frequency and opposite.Unit Herz (Hz) refers to frequency.
FrequencyAs you know, audio range of human perception is: 20Hz for the lowest to the maximumof 20.000Hz for the highest. Of course, there are the acoustic occurrence that relate tofrequencies under 20Hz (infrasound) and over 20KHz (ultrasound). But for this purposewe will discuss only for range of frequency that human ear can hear.
FrequencyIn acoustics, the wavelength is changing in large limits.Thus, for lowest frequency of 20Hz, wavelength is 17 m, as forthe highest frequency of 20KHz is 1.7 cm.
FrequencySimple sound means the sound in its spectrum has only onecomponent at a specific frequency and intensity (level).In the nature simple sound is a very rare. The whistle is the closest tosimple sound. Although, we can get a simple sound of the tone-generator. Example, 420Hz sine tone.Complex sound has two or more components. Separate two different complexsounds: one is from music instruments were we hear native tones, and another isnoise (continuity among two frequency, such as traffic jam or white/pink noise) Frequency of 1KHz is taken as the central to audio range.
FrequencyIn music, an octave is the interval between one musical pitch and another withhalf or double its frequency.According to that we can split our audio range up to 10 octaves.First octave is 20Hz to 40Hz,Second: 40Hz to 80Hz ….160Hz, 315Hz, 625Hz, 1250Hz, 2500Hz, 5KHz, 10KHz, 20KHz.Low Bass1st and 2nd octaves20-80HzThese are the frequencies associated with power, boom, and fullness.Lowest notes of the piano, organ, tuba and bass are in this range.Low frequencies of traffic, thunder, explosions.Sounds in these octaves need not occur often to maintain a sense of fullness.
FrequencyUpper Bass3rd and 4th octaves80Hz-320HzWe perceive them as giving sound an anchor–fullness or bottom.Most of the lower tones generated by rhythm and other support instrumentssuch as drums, piano, bass, cello, trombone and French horn are in this range..Midrange5th, 6th and 7th octaves320Hz-2560HzGives sound its intensity.Contains the fundamental and the rich lower harmonics and overtones of mostsound sources.Too much emphasis of 6th octave is heard as a hornlike quality, too much of 7this heard as a tinny quality.Extended listening to midrange sounds can be annoying and fatiguing.
FrequencyUpper Midrange8th octave2,560Hz - 5,120HzWe are most sensitive to this octave.Gives sound definition, clarity and realism.Improves intelligibility of speech.Treble9th and 10th octaves5,120Hz - 20,000HzThese 2 octaves generate only 2 percent of the total power output of the soundfrequency.Give sound the vital, lifelike qualities of brilliance and sparkle.Increasing loudness at 5kHz, the heart of the presence range, gives theimpression that there has been an overall increase in loudness throughout themidrange.
FrequencyReverberation time depends on frequency as well.In general, at the lowest frequency is good to have more reverb on it, especially in themusic, because that gives sound certain fullness. Room Optimal reverb time on 1KHz [s]1. Speech Studio 0.2 – 0.42. Auditoriums Conference Rooms 0.7 – 0.93. Cinema 1.0 – 1.14. Opera House 1.2 – 1.45. Concert Hall 1.7- 2.06. Church 3.0 – 4.0