Perception of sound  (Page 2/3)

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The screencast video of illustrates two different approaches to this problem, and demonstrates the perceptual effects that result from treating pitch perception as linear instead of logarithmic.

Intensity and amplitude

Perception of sound intensity also logarithmic. When you judge one sound to be twice as loud as another, you actually perceive the ratio of the two sound intensities. For example, consider the case of two people talking with one another. You may decide that one person talks twice as loud as the other, and then measure the acoustic power emanating from each person; call these two measurements ${T}_{1}$ and ${T}_{2}$ . Next, suppose that you are near an airport runway, and decide that the engine noise of one aircraft is twice the intensity of another aircraft (you also measure these intensities as ${A}_{1}$ and ${A}_{2}$ ). In terms of acoustic intensity, the difference between the talkers ${T}_{2}-{T}_{1}$ is negligible compared to the enormous difference in acoustic intensity ${A}_{2}-{A}_{1}$ . However, the ratios ${T}_{2}/{T}_{1}$ and ${A}_{2}/{A}_{1}$ would be identical.

The decibel (abbreviated dB ) is normally used to describe ratios of acoustic intensity. The decibel is defined in :

${R}_{\text{dB}}=10{\mathrm{log}}_{10}\left(\frac{{I}_{2}}{{I}_{1}}\right)$

where ${I}_{1}$ and ${I}_{2}$ represent two acoustic intensities to be compared, and ${R}_{\text{dB}}$ denotes the ratio of the two intensities.

Acoustic intensity measures power per unit area, with a unit of watts per square meter. The operative word here is power . When designing or manipulating audio signals, you normally think in terms of amplitude , however. The power of a signal is proportional to the square of its amplitude. Therefore, when considering the ratios of two amplitudes ${A}_{1}$ and ${A}_{2}$ , the ratio in decibels is defined as in :

${R}_{\text{dB}}=20{\mathrm{log}}_{10}\left(\frac{{A}_{2}}{{A}_{1}}\right)$

Can you explain why "10" becomes "20"? Recall that $\mathrm{log}\left({a}^{b}\right)=b\mathrm{log}\left(a\right)$ .

Often it is desirable to synthesize an audio signal so that its perceived intensity will follow a specific trajectory . For example, suppose that the intensity should begin at silence, gradually increase to a maximum value, and then gradually decrease back to silence. Furthermore, suppose that you should perceive a uniform rate of change in intensity.

The screencast video of illustrates two different approaches to this problem, and demonstrates the perceptual effects that result from treating intensity perception as linear instead of logarithmic.

Harmonics and overtones

Musical instruments produce sound composed of a fundamental frequency and harmonics or overtones . The relative strength and number of harmonics produced by an instrument is called timbre , a property that allows the listener to distinguish between a violin, an oboe, and a trumpet that all sound the same pitch. See Timbre: The Color of Music for further discussion.

You perhaps have studied the concept of Fourier series, which states that any periodic signal can be expressed as a sum of sinusoids, where each sinusoid is an exact integer multiple of the fundamental frequency; refer to :

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
Do somebody tell me a best nano engineering book for beginners?
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
how did you get the value of 2000N.What calculations are needed to arrive at it
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