Sound production theory Flashcards
What affects the speed of sound
The speed of sound in air is determined by the conditions of the air, not by waveform characteristics such as amplitude, frequency, or wavelength
In a sound cycle what is another name for the crest?
Compression
In a sound cycle what is another name for the trough?
Rarefraction
How many degrees are in 1 cycle
360 degrees
What is at 90 degrees in a sound cycle?
Crest/Compression
What is at 270 degrees in a sound cycle?
Trough/Rarefraction
What is frequency of sound measured in?
Hertz(Hz) or Cycles per second(cps)
how many cycles per second will a 100Hz frequency complete?
100 cycles per second
in common usage how would you often refer to a 4000Hz frequency
often refer to kilohertz simply as “k.” For example, it’s common just to say, “I boosted the vocal
track at 4k.”
what is The frequency response range of the human ea
roughly 20Hz-20,000Hz
Pitch - What is the name of the distance from a note to the next note of the same name
Octave
Mathematically, what is the difference in frequency between an pitch and an octave above?
twice the frequncy
Mathematically, what is the difference in frequency between a pitch and an octave below?
half the frequency
do Low frequencies have longer or shorter waveforms than high frequencies
longer
what greek letter is often associated with wavelength?
the greek letter lambda (ƛ)
how do you calculate wavelength?
To calculate the wavelength (ƛ), we use a formula consisting
of the frequency (f) specified in cycles/second, and the speed, or velocity, of sound specified in feet/second
(v). Wavelength (ƛ) = velocity(v) ÷ the frequency (f). ƛ=v/f
What is the formula for calculating wavelength?
ƛ=v/f
what is the simple definition of amplitude?
Amplitude expresses the amount of energy in a specified sound wave
whats the difference in a sound cycle where two waveforms on a graph where one with twice the amplitude of the other
the waveform with twice the amplitude has a crest that
rises twice as high and a trough that dips twice as low.
what is wavelength(ƛ) measured in?
Meters(M)
What is The speed at which sound waves travel in air
about 340 m/s at room temperature, but it varies
quite a bit with changes in temperature and humidity
what is the notation of the speed of sound?
c
On a Graphical Representation of Sound Wave what is the variable on the X axis
Air Pressure
On a Graphical Representation of Sound Wave what is the variable on the Y axis
Time
What is the symbol for gain?
A - however gain is a unitless measurement, so you can find A=V(out)/V(in) and not 15A just 15
Gain - if output is bigger than input is the gain <,= or > than 1?
Greater than 1
Gain - if output is equal to input is the gain <,= or > than 1?
equal to 1
Gain - if output is less than input is the gain <,= or > than 1?
Less than 1
Number prefix’s - What does the prefix μ stand for?
Micro. µ is a unit prefix in the metric system denoting a factor of 10−6 (one millionth), so add 6 zero’s
Number prefix’s - What does the prefix m stand for?
Milli. m is a unit prefix in the metric system denoting a factor of 10−3 (one millionth), so add 3 zero’s
What is the formula for gain?
A=output/input. This could be power, volatge or current
Logarithms - what is the base unit?
The number being raised to a power. eg a^n, a is the base
Logarithms - what is the exponent?
The power the base is being raised to. eg a^n, n is the exponent.
What is a logaritm?
A logarithm is the power to which a number must be raised in order to get some other number. For example, the base ten logarithm of 100 is 2, because ten raised to the power of two is 100: log 100 = 2. because. 102 = 100.
Logaritms - If a^n=y the n=?
loga(y)=n
Describe the expression loga(y)
This is called the logaritm of y and the logaritm is said to have a base of a
What logaritm is used for decibel calculations?
Base 10 log. So log10()
Logaritms Rule 3 - Rewrite loga(y^r)
r x loga(y)
Logaritms Rule 4 - what does loga(1) equal?
zero
Logaritms Rule 4 - if a logaritm of any number is bigger than 1 is it positive or negative?
Positive
Logaritms Rule 4 - if a logaritm of any number is less than 1 is it positive or negative?
Negative
How do we percieve sound? Linear or exponetial
Exponetially
Decibels - Which one does not need to be squared?
Volts, Watts. Pressure or Distance?
Inverse square law - how much does sound pressure level (SPL) reduce by when. distance is doubled?
-6db
Inverse square law - In this equation, dL =Lp2-Lp1, what does dL stand for?
dL = difference in sound pressure level (SPL) measured in dB
Inverse square law - In this equation, dL =Lp2-Lp1, what does Lp1/2 stand for?
Lp1/2 = sound pressure level (SPL) measured in dB
Inverse square law - How do you calculate dL (difference in SPL) using distance?
dL = 20log(R2/R1)
Inverse square law - If the SPL is 102 db from 1m from the source, what calculation would you use to work out the SPL at 5m?
Lp2 = 20log(5/1)
When power ratio is doubled what is the increase in dB?
3db
Whats the difference between sound pressure and sound pressure level?
A sound pressure is the pressure deviation from atmospheric pressure caused by a sound wave, in pascals. The sound pressure level (SPL) is a logarithmic measure of the ratio of a sound pressure over a reference sound pressure (corresponding to the hearing threshold of a young, healthy ear), quoted as a dB.
sound pressure = pascals(Pa)
sound pressure level = decibels(dB)
